Tecumseh 2 Cycle Repair Manual AH520 AH600 AV520 AV600 HSK600 TVS600


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TECUMSEH

T E C H N I C I A N ' S H A N D B O O K

This manual covers the following basic type or model numbers dependent on age of product: AH520, AH600, AV520, AV600, HSK600, TVS600.

This manual covered many engines under an Old form of

Identification which will need to be reviewed as well. TYPE / SPECIFICATION NUMBER 638-670 1398-1642 and Craftsman 200 Series Models.

2-CYCLE

ENGINES

Contents

i

This manual contains information on Tecumseh Engines built to comply with emission regulations. As a technician it is unlawful to modify or cause a change in the original calibration of these engines. All speed adjustments must remain within the limits that are specified for each engine, and are not to exceed the maximum. Any deviation must be specifically approved by Tecumseh Products Company.

ii

GENERAL INFORMATION

ENGINE IDENTIFICATION

Tecumseh has used two different methods of identifying 2 cycle engines. The first method was used until the mid 1980's using the base model number with a type number. The type number was used to identify variations for the OEM's specific needs (Fig. 1)

FRONT SIDE

 

 

 

T-670

 

 

 

 

TYPE

 

 

 

 

 

 

 

 

 

TECUMSEH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6874603

 

 

 

SERIAL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NUMBER

REVERSE SIDE

 

 

75

 

 

 

 

 

1975 YEAR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

30

 

 

 

 

 

30th DAY

(BUILD DATE)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5th. MONTH

 

 

5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(MAY)

 

 

 

 

 

 

 

 

 

 

 

 

1401J

 

TYPE

 

 

 

 

 

TYPE

 

 

670-100

 

 

 

 

 

 

 

 

 

TECUMSEH

 

 

 

TECUMSEH

 

 

 

SERIAL

 

62290322

 

 

 

SERIAL

6219

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NUMBER

 

 

 

 

 

 

 

 

NUMBER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YEAR 229th DAY

YEAR 219th DAY

 

1976

or Aug. 17th

1976 or Aug. 6th

 

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The second method was put in place to standardize 2 cycle and 4 cycle engine identification. The type number has now become the specification number, which is preceded by the engine model as illustrated in Figure 2 and 3.

TVS600-661030M 7352

Following the engine size are the engine specification numbers which are used for identification when ordering parts.

The final set of numbers are the date of manufacture (D.O.M.).

Example: HSK600 1688S

HSK

- Horizontal Snow King

600- 6 Cubic Inch displacement

1688S - Specification number

8023B - Serial number D.O.M. (date of manufacturing previously serial number)

8- First digit is the year of manufacturing

(1998)

023- Indicates the calendar day of the year (23th day or Jan. 23, 1998)

B- Represents the line and shift on which the engine was built at the factory

FUEL REGULAR UNLEADED

FUEL/OIL MIX 32:1

HSK600-1688S 8023B

3

Tecumseh engine model, specification, and D.O.M. number are now located on a decal adhered to the blower housing.

TVS600

-

 

661030M7352

 

2

INTERPRETATION OF MODEL NUMBER

The letter designations in a model number indicates the basic type of engine.

AH - Aluminum Horizontal AV - Aluminum Vertical BV - Outboard Vertical HSK - Horizontal Snow King TVS - Tecumseh Vertical Styling

The numbers that follow the letter designations indicate the horsepower or cubic inch displacement.

FUEL REGULAR UNLEADED

FUEL/OIL MIX 32:1

HSK600-1688S

8023B

4

1

ENGINE CARE

SHORT BLOCK IDENTIFICATION TAG

SBV OR SBH IDENTIFICATION NUMBER

SBV-2316

SER 4291

SERIAL NUMBER

SHORT BLOCKS

New short blocks are identified by a tag marked S.B.H. (Short Block Horizontal) or S.B.V. (Short Block Vertical). Original model identification numbers of an engine should always be transferred to a new short block for correct parts identification.

THIS SYMBOL POINTS OUT IMPORTANT SAFETY INSTRUCTIONS WHICH IF NOT FOLLOWED COULD ENDANGER THE PERSONAL SAFETY OF YOURSELF AND OTHERS. FOLLOW ALL INSTRUCTIONS.

ENGINE FUEL MIX

 

 

U.S.

U.S.

METRIC

METRIC

 

 

 

 

Amount of Oil

 

Amount of Oil

 

Gasoline

To Be Added

Petrol

To Be Added

24:1

1

Gallon

5.3 oz.

4 Liters

167 ml

 

2

Gallons

10.7 oz.

8 Liters

333 ml

 

 

 

 

 

 

 

32:1

1

Gallon

4 oz.

4 Liters

125 ml

 

2

Gallons

8 oz.

8 Liters

250 ml

 

 

 

 

 

 

 

50:1

1

Gallon

2.5 oz.

4 Liters

80 ml

 

2

Gallons

5.0 oz.

8 Liters

160 ml

 

 

 

 

 

 

 

FUELS. Tecumseh Products Company strongly recommends the use of fresh, clean, UNLEADED regular gasoline in all Tecumseh Engines. Unleaded gasoline burns cleaner, extends engine life and promotes good starting by reducing the build up of carbon deposits. Premium gas or gasohol containing no more than 10% ethanol can be used if unleaded fuel is not available.

NOTE: NEVER USE GASOLINE CONTAINING METHANOL, GASOHOL CONTAINING MORE THAN 10% ETHANOL, UNLEADED REGULAR GASOLINE CONTAINING MORE THAN 15% M.T.B.E. OR ETBE,

GASOLINE ADDITIVES, OR WHITE GAS BECAUSE ENGINE/FUEL SYSTEM DAMAGE COULD RESULT.

NOTE: In countries where unleaded gasoline is not available, regular gas can be used.

Make sure that gasoline and oil are stored in clean, covered, rust free containers. Dirt in fuel can clog small ports and passages in the carburetor. Use fresh gasoline only. Gasoline standing for long periods of time develop a gum that will result in fouled spark plugs, clogged fuel lines, carburetors and fuel screens.

Using fuel that is not fresh will cause engines to be hard starting, especially in cold temperatures.

Clean gas cap, tank and fuel container spout when filling fuel tank, to assure that dirt will not get into fuel system.

If gasohol is used, special care is required when the engine is to be stored for extended periods.

ENGINE OIL. Use Clean, high quality 2 CYCLE OIL. NMMA TC-WII, or TC-W3.

FUEL/OIL MIX. Follow fuel and engine oil requirements listed in the Owner’s Manual. Disregard conflicting instructions found on oil containers.

NOTE: Sears Craftsman models use a 40:1 mix which is acceptable.

NOTE: ALWAYS DOUBLE THE AMOUNT OF OIL FOR THE FIRST GALLON OF MIX FOR ENGINE BREAK IN.

To assure thorough mixing of oil and gasoline, fill container with gasoline to one quarter full, add oil as recommended, shake container vigorously and then add remainder of gasoline. Do not mix directly in

engine or equipment fuel tank.

TWO-CYCLE FUEL/OIL MIX RATIOS

24:1

AV520 All Basic Specifications 670 & 653 AV600 All Basic Specifications 600-10 & Up

32:1

TVS600 All Specifications

AH600

50:1

HSK600

STORAGE:

NEVER STORE ENGINE WITH FUEL IN TANK INDOORS OR IN ENCLOSED, POORLY VENTILATED ENCLOSURES WHERE FUEL FUMES MAY REACH AN OPEN FLAME, SPARK OR PILOT LIGHT AS ON A FURNACE, WATER HEATER, CLOTHES DRYER, ETC.

If engine is to be stored over 30 days, prepare for storage as follows:

1.Remove all gasoline from fuel tank to prevent gum deposits from forming in tank and other fuel system components, causing possible malfunction of the engine.

DRAIN FUEL INTO APPROVED CONTAINER OUTDOORS, AWAY FROM OPEN FLAMES.

Run engine until fuel tank is empty and engine stops due to lack of fuel.

Fuel stabilizer (such as Tecumseh's Part No. 730245) is an acceptable alternative in minimizing the formation of fuel gum deposits during storage.

2

Add stabilizer to fuel in fuel tank or storage container. Always follow mix ratio found on stabilizer container. Run engine at least 10 minutes after adding stabilizer to allow it to reach carburetor.

If gasohol has been used, complete preceding instructions and then add a small amount, one pint or less, of unleaded regular automotive gasoline properly mixed with the specified lubricating oil and run the engine until the fuel tank is empty and the engine stops due to lack of fuel.

2.Pull starter handle slowly until resistance is felt due to compression pressure, then stop. Release starter tension slowly to prevent engine from reversing due to compression pressure. This position will close both the intake and exhaust ports to prevent corrosion of the piston and the cylinder bore.

3.Clean unit by removing any dirt from exterior of the engine and equipment.

TUNE-UP PROCEDURE. The following is a minor tune- up procedure. Repair procedures for this engine and it’s components are listed in this manual if the engine does not perform to satisfaction after tune-up is performed.

CAUTION: Remove spark plug wire before doing any service work on engine.

1.Service or replace air cleaner as necessary.

NOTE: Snow King® engines do not use an air filter due to the clean operating environment and to prevent filter freeze-up.

2.Remove blower housing, clean all dirt, grass or debris from air intake screen, cylinder cooling fins, and carburetor governor levers and linkage.

3.Remove carburetor, clean and install a carburetor kit, make adjustment presets where needed. Presets are found in the carburetor section of this manual. Make sure fuel tank, fuel filters and fuel lines are clean. Reinstall carburetor, replacing any worn or damaged governor springs or linkage. Make proper governor adjustment. Adjustments are found in the manual under governor linkage and adjustment and engine reassembly.

4.Replace the spark plug with a correct equivalent.

5.Make sure all ignition wires are properly routed, so they will not rub on flywheel. Inspect all ignition wires for abrasion or damage. Remove flywheel and check flywheel key, reinstall flywheel, torque flywheel nut to specifications. Set air gap between solid state module and flywheel at .0125'’. Air gap gauge, part no. 670297 may be used.

6.The engine must be firmly mounted to the associated equipment. On rotary lawnmowers, make sure blade is properly balanced and correctly torqued. See disassembly section for flywheel removal and air gap setting procedure.

7.Make sure all remote linkage is properly adjusted for operation.

8.Fill tank with the proper fuel/oil mix.

9.Start the engine, allow it to warm up 5 minutes, then adjust carburetor and engine R.P.M. according to Tecumseh’s recommendations.

Snow King® engines should be run in outdoor temperatures for engine adjustments.

NOTE: Emissionized engines have non-adjustable carburetors in compliance with CARB (California Air Resource Board) and U.S. EPA (United States Environmental Protection Agency). These engines can not be modified without specific authorization.

COMPRESSION

RELEASE

PASSAGE

EXHAUST PORT CLEANING. The exhaust ports should be cleaned after each seventy-five (75) to one hundred (100) hours of use.

Before cleaning the ports place the piston in the Bottom Dead Center position. Then clean the ports using a pointed 3/8'’ diameter wooden dowel or similar tool. Be sure not to scratch the port area. Also remember to remove all the loose carbon particles from the engine.

NOTE: When cleaning the exhaust ports, check and clean the compression release passage.

3

2-CYCLE THEORY OF OPERATION

Air cooled 2-cycle engines differ from 4-cycles by having one power stroke for every revolution of the engine versus every other stroke on 4-cycles.

1. INTAKE AND IGNITION 2.

COMPRESSION

3.

POWER

4.

OPERATION OF PISTON PORT STYLE.

A low pressure area is created in the crankcase as the piston moves upward to compress the air/fuel mixture in the cylinder. When the piston moves far enough to uncover the intake port, the air/fuel mixture from the carburetor flows into the engine crankcase due to higher pressure atmospheric air. Just before the piston reaches top dead center (TDC), the spark plug ignites the air / fuel mixture in the cylinder.

The expanding combustion gases force the piston down. The downward piston travel causes a pressure buildup in the crankcase. The piston uncovers the exhaust port first, followed by the transfer ports. The exhaust flows out the exhaust port while the pressurized air/ fuel mixture enters the cylinder from the crankcase through the transfer ports. As the piston travels upward the sequence is repeated.

OPERATION OF REED PORTED STYLE WITH LOOP SCAVENGING

The following illustrates the loop scavenge design which uses a vacuum-pressure activated reed valve. Here the ports are located on three sides of the cylinder; the intake ports are on two sides opposite each other, and the exhaust ports are illustrated by the three holes just above the head of the piston.

As the mixture flows into the combustion chamber through the transfer ports, it collides and is directed to the top of the combustion chamber looping when it strikes the cylinder head, thus forcing all spent gases out through the open exhaust ports.

TERMS. Listed are common terms often referred to on 2-cycle engines.

EXHAUST or SCAVENGE PHASE. The burned gases must be cleared out of the combustion chamber and replaced by a fresh charge of fuel-air mixture through the intake ports. The exhaust passes out through the exhaust ports into the outside air.

PORTS. Openings in the cylinder allow gases to pass into and out of the combustion chamber. The ports are opened or closed by the upward and downward movement of the piston.

EXHAUST PORTS. Allow the burned gases to pass out of the combustion chamber.

THIRD PORT (Sometimes called piston port). A third port is for entry of the fuel-air and oil mixture to the crankcase. From the crankcase the fuel-air mixture enters the combustion chamber through the intake ports. The third port is controlled by the piston skirt.

REED VALVE. A reed valve is activated by crankcase pressure or vacuum. A decrease in crankcase pressure opens the reed allowing the fuel air and oil mixture to enter the crankcase. Increased crankcase pressure closes the valve, preventing escape of the fuel-air and oil mixture back through the carburetor.

LUBRICATION. Tecumseh 2-cycle engines are lubricated by a gas oil mix. The correct mix ratio of oil and gas combines with air in the venturi and enters the crankcase. During engine operation the oil clings to all the internal moving parts for lubrication.

4

AIR CLEANERS, CARBURETORS, GOVERNORS

AND LINKAGE

AIR CLEANERS

Service the air cleaner frequently to prevent clogging of the cleaner and to prevent dust and dirt from entering the engine. Dust bypassing an improper or damaged air filter can quickly damage an engine. Always make certain covers and air cleaner connections are tightly sealed to prevent entry of dirt.

NOTE: Snow King® models do not use air cleaners due to the clean environment that they operate in and also to prevent air cleaner freeze-up.

When excessive carburetor adjustment or loss of power results, inspect the air filter for clogging.

NOTE: Use factory recommended parts only.

POLYURETHANE-TYPE AIR CLEANER. These serviceable air cleaners utilize a polyurethane element which will clog up with use. The element should be cleaned and serviced in the following manner.

Wash element in a detergent and water solution and squeeze (don’t twist) until all dirt is removed. Rinse thoroughly.

Wrap in clean cloth and squeeze (don’t twist) until completely dry.

Clean air cleaner housing and cover. Dry thoroughly.

Re-oil element by applying generous quantity of oil to all sides. Squeeze vigorously to distribute oil and to remove excess oil. (S.A.E. 30)

When reassembling polyurethane oval type air cleaners, place cupped screen into housing with edge against carburetor end of housing. Screen should be installed to hold element away from housing to allow full utilization of air cleaner element.

NOTE: Polyurethane type filters will lose effectiveness if stored for extended periods of time, due to oil migration (settling Down) through the filter. Re-oil filter as necessary.

CUPPED SCREEN MUST BE

POSITIONED WITH EDGES AWAY

FROM ELEMENT

COVER

POLYURETHANE

ELEMENT

FLOCKED

SCREEN

KLEEN-AIRE® SYSTEM. This system uses a polyurethane type element. Service as described under polyurethane-type air cleaner. When removing air cleaner body from carburetor, remove plug in the body to gain access to the mounting screw. Make certain plug is put back in place. If it shows damage, replace.

POLYURETHANE

ELEMENT

PLUG MUST BE

IN PLACE

FLOCKED

SCREEN

PAPER-TYPE AIR CLEANER SERVICE. Replace air filter once a year or more often in extremely dusty or dirty conditions.

DO NOT ATTEMPT TO CLEAN OR OIL PAPER-TYPE FILTER.

Be sure to clean base and cover thoroughly before installing new paper filter.

NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER INSTALLED ON THE ENGINE.

NOTE: Serious damage to the engine may result in using any other but the specified part number filter. Use factory recommended parts only.

5

GENERAL CARBURETOR INFORMATION

CARBURETOR IDENTIFICATION. Tecumseh carburetors are identified by a manufacturing number and code date stamped on the carburetor as illustrated.

ALTERNATE LOCATION

FOR MANUFACTURING NUMBER

89

4 F5

89

4 F 5

 

CARBURETOR

CARBURETORCODE DATE MANUFACTURING NUMBER

When servicing carburetors, you may use either the engine model specification number or the manufacturing number on the carburetor to properly identify. Information regarding replacement parts or kits are available in the master parts manual, microfiche catalog or electronic parts look-up systems.

Tecumseh uses two basic types of carburetors for their 2 cycle engines, float-type and diaphragm.

FLOAT-TYPE CARBURETORS. Float-type carburetors use a hollow metal float to maintain the operating level of fuel in the carburetor. As the fuel is used, the fuel level in the carburetor bowl drops and the float moves downward. This actuates the inlet needle valve, to allow fuel to flow into the fuel bowl. As the fuel level in the bowl again rises, so will the float. This float action adjusts the fuel flow and keeps the fuel at the proper mixture level. Some carburetors are of the fixed main type. On these models, the main adjusting screw and nut are replaced by a fixed main jet bowl nut.

 

IDLE FUEL

IDLE AIR

 

 

CHAMBER

CHOKE

THROTTLE

BLEED

 

SHUTTER

 

 

SHUTTER

SECONDARY IDLE

 

 

 

DISCHARGE

 

 

AIR

 

 

 

PRIMARY

 

 

BLEED

 

 

 

IDLE DISCHARGE

 

 

 

*IDLE

INLET

SEAT

ADJUSTMENT

 

SCREW

 

 

INLET

 

 

 

 

IDLE FUEL

NEEDLE

 

TRANSFER

 

PASSAGE

FLOAT

REDUCTION ROD

 

IDLE FUEL

*MAIN ADJUST

TRANSFER PASSAGE

*Both jets may be fixed - non adjustable

DIAPHRAGM (PRESSURE DIFFERENTIAL) CARBURETORS

This type of carburetor uses a rubber-like diaphragm which is exposed to intake manifold pressure on one side and to atmospheric pressure on the other. Tecumseh diaphragm carburetors use the diaphragm as a metering device. As the intake manifold pressure decreases due to downward piston travel, the atmospheric pressure on the vented side of the diaphragm moves the diaphragm against the inlet needle. The diaphragm movement overcomes the spring tension on the inlet needle and moves the inlet needle off the seat. This permits the fuel to flow through the inlet valve to maintain the correct fuel volume in the fuel chamber. The inlet needle return spring closes the inlet valve when the pressure on the diaphragm equalizes or a pressure higher than atmospheric exists on the intake side (upward piston travel). The diaphragm meters a correct fuel volume in the fuel chamber to be delivered to the mixing passages and discharge ports.

A main or idle adjustment needle may be replaced by an internally fixed jet on some models.

The main nozzle contains a ball check valve. The main purpose of this ball check is to eliminate air being drawn down the main nozzle during idle speeds and leaning the idle mixture.

An advantage of the diaphragm carburetor over the float system is that the diaphragm carburetor increases the angle that the engine may be operated at.

AIR BLEED

CHECK

IDLE ANDBALL INTERMEDIATE

PORTS

THROTTLE

 

CHOKE

SHUTTER

 

SHUTTER

IDLE

 

FUEL

ADJUST

 

 

INLET

MAIN

 

 

 

ADJUST

 

 

 

 

INLET

 

 

NEEDLE

 

DIAPHRAGM

AND

 

SEAT

 

 

6

OPERATION

In the “CHOKE” or “START” position, the choke shutter is closed, and the only air entering the engine enters through openings around the shutter. As the engine starts to rotate the downward piston travel will create a low air pressure area in the engine cylinder above the piston. Higher pressure (atmospheric air) rushes into the engine to fill the created low pressure area.

Remove all welch plugs if cleaning the carburetor. Secure the carburetor in a vise equipped with protective jaws. Use a small chisel sharpened to a 1/8" wide wedge point. Drive the chisel into the plug to pierce the metal and push down on the chisel to pry the plug out of the hole.

Clean all metallic parts with solvent.

Since the majority of the air passage is blocked by the choke shutter, a relatively small quantity of air enters the carburetor at increased speed. The main nozzle and both idle fuel discharge ports are supplying fuel due to the low air pressure in the intake of the engine. A maximum fuel flow through the carburetor orifices combined with the reduced quantity of air that passes through the carburetor, make a very rich fuel mixture which is needed to start a cold engine.

At engine IDLE speed, a relatively small amount of fuel is required to operate the engine. The throttle is

SMALL

CHISEL

PRY OUT

PLUG

DO NOT ALLOW CHISEL POINT TO STRIKE CARBURETOR BODY OR CHANNEL REDUCER

PIERCE PLUG WITH TIP

WELCH PLUG

TO BE REMOVED

ABOUT 1/8" WIDE

almost completely closed. A fuel / air mixture is supplied through the primary idle-fuel discharge orifice during idle.

During INTERMEDIATE engine operation, a second orifice is uncovered as the throttle shutter opens, and more fuel mixture is allowed to atomize with the air flowing into the engine.

During HIGH SPEED engine operation, the throttle shutter is opened. Air flows through the carburetor at high speed. The venturi, which decreases the size of the air passage through the carburetor, further accelerates the air flow. This high speed movement of the air decreases the air pressure at the main nozzle opening. Fuel is forced out the main nozzle opening due the difference in the atmospheric air pressure on the fuel in the carburetor bowl and the reduced air pressure at the main nozzle opening.

CARBURETOR SERVICE. Carefully disassemble carburetor, removing all non-metallic parts, i.e., gaskets, viton seats and needles, “O” rings, fuel pump valves, etc.

Nylon check balls used in some diaphragm carburetors are not serviceable. Nylon can be damaged if subjected to harsh cleaners for prolonged periods.

Remove the primer bulb (if equipped) by grasping with a pliers and pulling and twisting out of the body. Remove the retainer by prying and lifting out with a screwdriver. Do not re-use old bulb or retainer.

SMALL CHISEL

To install a new welch plug after cleaning, place welch plug into receptacle with raised portion up. With a punch equal to the size of the plug, merely flatten the plug. Do not dent or drive the center plug below the top surface of the carburetor. After installing the welch plug, seal the outer diameter with finger nail polish. (Do not use clear polish).

 

 

FLAT-END PUNCH

 

 

NEW WELCH PLUG

SAME OR LARGER

DIAMETER OF PLUG

 

THROTTLE. Examine the throttle lever and plate prior to disassembly. Replace any worn and/or damaged parts.

When reassembling, it is important that the lines on the throttle plate are facing out when in the closed position. Position throttle plates with the two lines at 12 and 3 o’clock. If throttle plate has only one line, the line should be positioned in the 12 o’clock position. If binding occurs, correct by loosening the screws and repositioning the throttle plate.

THROTTLE LEVER

THROTTLE PLATE

7

CHOKE. Examine the choke lever and shaft at the bearing points and holes into which the linkage is fastened, and replace if worn or damaged. The choke plate is inserted into the air horn of the carburetor in such a position, that the flat side of the choke is down. Before disassembly note the direction of choke plate movement. Choke plates will operate in either direction. Make sure it is assembled properly for your engine.

CHOKE PLATE

DOWN TOWARD FUEL BOWL

ADJUSTING SCREWS. Remove the adjusting screws from the carburetor body and examine the point, replace the screws if damaged. Tension is maintained on the screw with a coil spring. Examine and replace the “O” ring seal(s) if damaged.

NOTE: If screws are made of plastic, dip the end of the screw in oil before installation to prevent damage.

FUEL BOWL RETAINING NUT. The fuel bowl retaining nut has a fixed main jet incorporated in the nut. This small jet must be clean for proper fuel metering. Clean by using compressed air. DO NOT USE WIRE OR HARD OBJECTS FOR CLEANING.

CARBURETOR VENTING. Float-type carburetors must have atmospheric air pressure acting against the fuel in the fuel bowl. These vents can be external, with a hole drilled through the side of the carburetor casting or internal where atmospheric air is picked up in the air horn near the air cleaner. Regardless of the type, these vents must be clear and free from dirt, paint, grease, etc.

HIGH TILT FLOAT STYLE carburetors use an external main air bleed.

MAIN AIR BLEED

FUEL BOWL. The fuel bowl must be free of dirt and corrosion. When disassembling a carburetor for repair, always replace the fuel bowl “O” ring. Lubricate the “O” ring with a small amount of oil for easier installation.

Install the float bowl by placing the detent portion opposite of the hinge pin. Make sure the deepest end of the bowl is opposite of the inlet needle. The bowl has a small dimple located in the deepest part. The purpose of this dimple is to minimize the chances of the float sticking to the bottom of the bowl caused by stale fuel.

DETENT

FLOAT. Remove the float by pulling out the float hinge pin. Lift the float away from the carburetor body. This will also lift the inlet needle out of the seat.

Examine the float for damage. Check the float hinge bearing surfaces for wear, as well as the tab that contacts the inlet needle. Replace any damaged or worn parts.

EXAMINE FLOAT HINGE FOR WEAR AT BEARING SURFACES

INLET NEEDLE

INLET NEEDLE

CLIP

REMOVE FLOAT TO MAKE ADJUSTMENTS.

BEND THIS TAB TO ADJUST

Float sticking can occur due to fuel deposits (gum or varnish). This can be corrected by loosening the carburetor bowl nut one full turn and rotating the bowl 1/4 turn in either direction. Return the bowl to it's original position and retighten the bowl nut.

8

INLET NEEDLE AND SEAT (FLOAT CARBURETORS). Tecumseh carburetors are built with removable seats made out of a material called VITON®. These seats are easily removed by bending the end of a paper clip or wire with a 3/32" hook or use a #4 crochet hook. Push the hook through the hole in the center of the seat and remove it. Never reuse the old seat, always replace it with a new seat.

3/32"

HOOK END

To install a new seat, make sure the seat cavity is clean, then moisten the seat with a drop of oil to help it slide into place. Position the seat with the grooved side of the seal down and carefully push the seat into its cavity with a 5/32" flat punch until it bottoms out.

NEEDLE AND SEAT POP-OFF TEST

To test the pop-off pressure, remove the carburetor from the engine. Be sure to drain any fuel into an approved container. Invert the carburetor and remove the float bowl. Place a drop of an oil based product such as WD-40 on the tip of the needle valve. Using

acommercially available 0-30 psi pump and gauge, attach the pumps hose to the carburetor inlet. Apply approximately 6 psi or until the needle pops off the seat. The needle should seat at 1.5 psi or greater for

aminimum of 5 minutes. If the minimum 1.5 psi cannot be maintained for this period of time, then service to the needle and seat is required.

If the required adjustment is minor, the tab adjustment may be made without removing float and carefully inserting a small bladed screwdriver to bend the tab. Be careful not to damage other parts.

11/64" DRILL BIT

RIM

The idle on the Series 8 is metered using a threaded restrictor (See illustration). Proper torque of this restrictor is critical, it should be torqued to 5-8 in. lbs. or .5 to 1 nm, or it may vibrate loose. When the restrictor is placed in the idle circuit passage it is capped with a tamper resistant plastic cap. If the jet is removed for cleaning it must be recapped to prevent tampering when it is re-installed.

IDLE RESTRICTOR

CAP

The inlet needle hooks onto the float tab by means of a spring clip. To prevent binding, the long, straight, open end of the clip must face the choke end of the carburetor as shown.

5/32" FLAT PUNCH

DRIVE IN UNTIL

SEAT

 

SEAT RESTS ON

 

BODY SHOULDER

 

INLET NEEDLE

INSERT THIS

FACE FIRST

SEATS AT THIS

 

 

 

POINT

 

FLOAT HEIGHT SETTINGS

Previously the float height was set by using a 670253A float setting tool. The new float setting will require an 11/64" drill bit. The procedure for setting the float height is as follows. Remove the bowl gasket, then hold the carburetor in the inverted position. Place the drill bit across the carburetor body opposite and parallel to the float hinge pin. Adjust the float height by bending the tab on the float until it touches the bit.

CLIP

LONG END

OF CLIP

THROTTLE END

CHOKE END

9

The float dampening spring on the HIGH TILT FLOAT STYLE carburetor has an extended end which must point toward the choke end of the carburetor.

POINTS TOWARD

CHOKE END

FLOAT DAMPENING

SPRING

PRIMER BULB. To install, start the retainer and bulb into the casting with the retainer tabs pointed out. Firmly push the bulb and retainer into position using a 3/4" (19mm) deep well socket.

CLEANING CARBURETOR BODY. When removing choke and throttle shafts, check shafts and bearings in carburetor body for wear. Any looseness in these areas can cause dirt to enter the engine resulting in premature wear. If dust seals are present, they should be positioned next to the carburetor body. Install the dust seal, metal washer, and finally the return spring.

Welch plugs should be removed for proper cleaning of the carburetor (See welch plug service at the beginning of this section). When all accessories and shafts have been removed, soak the carburetor in carburetor cleaner for a maximum of 30 minutes. Blow out all passages with compressed air in the opposite direction of normal fuel flow.

The carburetor body on non-emission carburetors contains a main nozzle tube pressed into the carburetor body to a predetermined depth within the venturi of the carburetor. DO NOT attempt to remove this main nozzle. Any movement of this nozzle will seriously affect the metering characteristics of the carburetor. (Emissions carburetors have a serviceable plastic nozzle.)

Clean the well surrounding the main nozzle with carburetor

MAIN NOZZLE

DO NOT ATTEMPT TO REMOVE

cleaner and compressed air. With the choke plate and shaft removed, blow compressed air through the high speed air bleed located just behind the lower choke shaft bearing and immediately in front of the venturi to remove any dirt that may have accumulated.

Blow compressed air through all of the passages, making sure they are free of dirt, varnish or foreign material.

DIAPHRAGMS. Inspect diaphragms for cracks, tears or brittleness. Replace if necessary. Rivet head on diaphragm must always face toward the inlet needle valve.

If the carburetor has an "F" designation on the casting, it will identify the installation sequence of the gasket and diaphragm on the carburetor. "F" designated carburetors have the diaphragm installed first then the gasket then the cover. If there is no designation, the sequence is gasket, diaphragm and cover.

INLET NEEDLE AND SEAT. (Diaphragm Carburetors)

RIDGE AND

GASKETRIVET

HEAD UP

RIDGE AND

RIVET HEAD UP

GASKET

10

Use a socket to remove inlet needle and seat. Replace with complete assembly.

FUEL INLET FITTING. If necessary this fitting can

IDLE MIXTURE SCREW

MAIN MIXTURE SCREW

be removed by pulling and twisting. Be sure to install in the same position as the original. When installing fitting, insert tip into the carburetor body, then coat the exposed portion of the shank with Loctite 242 Blue; then press it in, until the shoulder contacts the carburetor body.

THE PRIMER BULB (DIAPHRAGM CARBURETOR).

PRESS IN PARTIALLY THEN APPLY LOCTITE "242 BLUE"

Pressing the bulb creates air pressure against the diaphragm. Fully depress primer bulb with your thumb, making sure that the vent hole in bulb is covered. Release and allow bulb to return to original position.

As the diaphragm lifts, the inlet needle is lifted off its seat and the fuel within the reservoir is fed up through the passages into the air horn. A one-way valve in the body prevents the fuel from being forced back into the fuel tank.

CARBURETOR CHECK VALVE. Diaphragm carburetors

PUSH RELEASE

with primers must have a check valve located in or behind the fuel inlet fitting of the carburetor. This is to prevent fuel from being forced back to the fuel line and tank when priming.

Two types of check valves have been used. One is a brass check valve pushed into the carburetor body in the fuel inlet. The other is a teflon disc located in the area under the fuel fitting. These two types of check valves are not interchangeable.

To remove the brass type check valve, drill a 9/64'’ (3.57 mm) hole through the center of the check valve, making sure drill does not travel more than 1/8'’ (3.17 mm) into the body and damage the carburetor.

Turn a nut on to a 8-32 tap and slide a washer on after it.

Turn the tap with nut and washer into the valve until the tap begins to protrude through the valve when viewed through the inlet needle and seat opening.

Turn the nut clockwise to pull the valve out from the carburetor body.

8-32 TAP

WASHER

The teflon disc-type can be cleaned by using low air pressure forced into the inlet fitting. If service is required, pull out inlet fuel fitting and replace the teflon disc. Put a drop of oil on the disc and position in the cavity of the carburetor. Replace fuel inlet fitting as outlined in Fuel Inlet Fitting instructions.

TEFLONBRASS

11

CARBURETOR SERVICE PROCEDURE

Check shaft for looseness or binding. Shutter must be positioned with detent reference marks on top parallel with shaft.

Check spring for return action and binding.

THROTTLE SHAFT AND LEVER

THROTTLE SHUTTER

DETENT

REFERENCE MARK

THROTTLE SHAFT

RETURN SPRING

IDLE SPEED ADJUSTMENT SCREW

Loosen screw until it just clears

 

throttle lever, then turn screw in 1

 

turn.

 

 

MAIN NOZZLE

Do not attempt to remove. Blow air

through passage.

 

CHOKE SHAFT

 

 

AND LEVER

Check shaft for binding.

CHOKE PLATE

 

 

 

 

MAIN NOZZLE

Blow air through passage. Do not re-

AIR BLEED

move restrictor if present.

 

 

Remove when cleaning and replace DUST SEALS with new seals.

INLET FITTING

SOFT BAFFLE PLUG

Clean with compressed air.

FUEL PICK UP

 

 

Clean with compressed air.

MAIN JET

 

 

*INLET NEEDLE AND SEAT

*FLOAT BOWL

GASKET

FLOAT SHAFT

INLET

NEEDLE CLIP

 

 

FLOAT

 

 

FLOAT BOWL

 

 

BOWL NUT

*GASKET

 

Proper installation is important. See appropriate chapter for procedures.

Replace.

Must hook over float tab.

Long straight end of clip must face the choke end of the carburetor.

Check float for leaks or dents. Clean bowl and adjust float level position gasket or gaskets.

Set float to proper level.

*NON METALLIC ITEMS - CAN BE DAMAGED BY HARSH CARBURETOR CLEANERS

Loosen screw until it just clears throttle lever, then turn screw in 1 turn.

Place detent reference mark to proper location. See chapter appropriate to specific carburetor.

Check spring for return action and binding.

Remove welch plug and blow air through air passages.

The check ball is a non serviceable item. Clean with carburetor spray and low air pressure only.

IDLE SPEED ADJUSTMENT SCREW

THROTTLE SHAFT AND LEVER

DETENT REFERENCE MARK ON THROTTLE SHUTTER

THROTTLE SHUTTER

THROTTLE SHAFT

RETURN SPRING

IDLE,

INTERMEDIATE

AND AIR BLEED

ORIFICES

*IDLE MIXTURE ADJUSTMENT SCREW AND "O" RING (If Present)

*MAIN MIXTURE ADJUSTMENT SCREW AND "O" RING (If Present)

*MAIN NOZZLE WITH CHECK BALL

CHOKE SHAFT AND LEVER

CHOKE SHUTTER

*INLET FITTING

*INLET SEAT GASKET

FUEL

*INLET NEEDLE SEAT AND SPRING ASSEMBLY

*DIAPHRAGM GASKET

*DIAPHRAGM

ATMOSPHERIC VENT HOLE

Check shaft for binding. Position shutter opening towards inlet fitting side of air horn.

Primer bulb models have a Teflon one way valve, in or behind the fitting.

Remove and replace.

Proper installation of assembly is important. See appropriate chapter for procedures.

Gasket and diaphragm sequence may be reversed on some models. Head of rivet must touch inlet needle.

Hole must be clean. On models with primer bulb, vent hole is very small and is located off center or in the

*NON METALLIC ITEMS - CAN BE DAMAGED BY HARSH CARBURETOR CLEANERS

primer bulb.

12

EMISSIONIZED DIAPHRAGM CARBURETION

Loosen screw until it just clears throttle lever, then turn screw in 1 turn.

Place detent reference mark to proper location. See chapter appropriate to specific carburetor.

Remove welch plug and blow air through air passages.

IDLE SPEED ADJUSTMENT SCREW

THROTTLE SHAFT LEVER AND RETURN SPRING

THROTTLE SHUTTER

IDLE,

INTERMEDIATE

AND AIR BLEED

ORIFICES

CHOKE SHAFT AND LEVER

Check shaft for binding. Position

CHOKE SHUTTER

shutter opening towards inlet fitting

side of air horn.

 

 

HIGH SPEED AIR BLEED

TAMPER RESISTANT CAP (Pierce to Remove)

*INLET SEAT Remove and replace.

GASKET

*INLET FITTING

*INLET NEEDLE SEAT AND SPRING ASSEMBLY

Primer bulb models have a Teflon one way valve, in or behind the fitting.

Proper installation of assembly is important. See appropriate chapter for procedures.

BLUE THREAD LOCK SEALANT APPLIED

FIXED IDLE

RESTRICTER JET

FIXED MAIN JET

MAIN NOZZLE WITH CHECK BALL

*DIAPHRAGM GASKET

*DIAPHRAGM

ATMOSPHERIC VENT HOLE

Gasket and diaphragm sequence may be reversed on some models. Head of rivet must touch inlet needle.

Hole must be clean. On models with primer bulb, vent hole is very small and is located off center or in the primer bulb.

OUTBOARD CARBURETORS

Carburetors on outboard applications use float type which have a separate idle speed fuel pickup tube pressed into the casting. The idle mixture screw is located on the top of the carburetor near the engine.

This carburetor has been manufactured with 2 different types of inlet needle and seats. One has a hard needle with a synthetic rubber seat, the other has a non- replaceable brass seat with a synthetic rubber tipped needle.

Outboard carburetors have a built-in fuel pump consisting of a fuel pump element which inflates and deflates with crankcase pulses which opens and closes two flap valves in the fuel pump, thereby pumping fuel from a remote tank to the carburetor float bowl.

When replacing the fuel pump element, install with the slot opening at a 45o angle as illustrated.

IDLE SPEED FUEL PICKUP

FUEL PUMP ELEMENT

13

As the engine's piston, moves upward, a partial vacuum is created in the crankcase, which collapses the fuel pump element in the carburetor. On the outside of the element, suction opens the inlet flap drawing a supply of fuel from the tank and lines into the cavity created by the deflating pump element. Suction pulls the outlet flap closed, sealing the outlet port so that fuel isn’t pulled from the area of the inlet needle and seat.

On the downward stroke of the piston, crankcase pressure

FUEL PUMP

ELEMENT DEFLATED INLET FLAP

VALVE

FUEL

INLET

OUTLET

FLAP

VALVE

enlarges the pump element forcing fuel out of its cavity. This pressurized fuel acts against the outlet flap valve, opening it, allowing a head of pressurized fuel to be transmitted to the inlet needle and seat port. The inlet valve is pressed against the inlet port, sealing it so that pressurized fuel does not escape back into the fuel tank and lines.

The flap valves are located between the cover and

FUEL PUMP

ELEMENT INFLATED

INLET FLAP

VALVE

FUEL

INLET

OUTLET

FLAP

VALVE

gasket. Make sure the flaps are in good condition and the strainer is not clogged or damaged. Replace as necessary. Make sure the cover is not warped; check by laying on a flat surface. If warped, replace. If not warped severely, it can be refaced using a hard surface and emery cloth. Notches on the carburetor body insure that the gasket, valve, and cover are positioned on the body correctly. When tightening screws, snug bottom screw, then top screw and torque to 6-8 in. lbs.

OUTBOARD CONTROL PANEL. Install the idle adjustment rod into the bracket then turn the setscrew 14

IF CURLED OR FRAYED REPLACE

GASKET

INLET FLAP

COVER

STRAINER OUTLET FLAP

into the rod a complete 2 turns.

Then position the extended end of the choke rod spring on the idle adjustment rod and align the spring with the choke rod holes in the bracket. Press the choke rod through the bracket and spring with the link attaching hole toward the carburetor side.

Install the choke shaft link in the rod, then install the other end in the choke lever.

Install the control bracket to the carburetor, but do not tighten screw completely.

Tighten the setscrew to secure the rod to the idle

 

LINK

 

CHOKE ROD

THROTTLE

ROD STOP

SPRING

LEVER POST

 

IDLE

BRACKET

ADJUST

 

NEEDLE

 

AND SPRING

IDLE ADJUST ROD

adjustment cable. The rod should turn about a half turn before contacting the extended end of the choke spring.

It is important that the idle adjustment screw be one full turn from closed, and that the rod setscrew be down (6 o'clock position) when connecting the rod and coil.

Tighten the control bracket screw. Pull the choke rod to assure that the choke shutter closes.

ABOUT 1/2 TURN

6O'CLOCK POSITION

FROM THE 6 O'CLOCK POSITION,

THE ROD WILL TURN ABOUT 1/2 TURN

EACH WAY BEFORE BEING STOPPED

BY THE SPRING ROD

CARBURETOR ADJUSTMENTS

Emission grade carburetors will have fixed main and idle circuits. The absence of adjustment screws indicate fixed jets with no adjustments necessary.

CARBURETOR ADJUSTMENTS

IDLE SPEED ADJUSTMENT

This screw is located on top of the carburetor and contacts the throttle. To pre-set the idle speed, back out the screw, then turn in until the screw just touches the throttle lever. Finally, turn the screw in one (1) turn. Once the engine is running and brought up to operating temperature (3-5 minutes), the final idle R.P.M. can be adjusted with the aid of a tachometer.

FLOAT TYPE-FIXED MAIN, IDLE ADJUST

Turn the mixture adjusting screw in (clockwise) finger tight, then one (1) turn out (counterclockwise). This setting is approximate and will be enough to allow the engine to start so that final carburetor adjustments can be made. Start the engine and allow it to warm- up for approximately 5 minutes. Do not adjust the carburetor with the engine cold.

NOTE: If the engine falters or stops after the choke lever is moved to the "OFF" position, open the mixture adjusting screw 1/4 turn counterclockwise and restart the engine.

With the engine running, place the speed control in the "slow" position. Turn the mixture adjusting screw clockwise until the engine starts to falter, remember this location. Next turn the screw counterclockwise until the engine start to sputter or drops in R.P.M., remember this location. Now turn the screw clockwise until it is halfway between these two locations. This will be the optimum carburetor setting.

DIAPHRAGM - SINGLE AND DUAL ADJUSTMENT Turn the mixture adjustment screw(s) clockwise finger tight, then one (1) turn counterclockwise. This setting will allow the engine to be started so that the carburetor can be fine tuned. Do not adjust the carburetor when the engine is cold.

Start the engine and let it warm-up for approximately 5 minutes. If the engine falters or stops after the choke lever is moved to the "OFF" position, turn the adjusting screw 1/4 turn counterclockwise and restart the engine.

NOTE: On dual adjust, the first adjustment must be made with the main mixture screw.

With the engine running, turn the mixture adjustment screw clockwise until the engine starts to falter, remember this location. Next turn the screw counterclockwise until the engine starts to sputter or drop in R.P.M., remember this location. Now turn the screw clockwise until it is halfway between these two locations. This will be the optimum carburetor setting.

With dual adjust carburetor, repeat the above steps for the second (idle) mixture adjusting screw.

SERIES I

IDLE MIXTURE

SCREWMAIN MIXTURE SCREW

SERIES III, IV

IDLE MIXTURE

MAIN MIXTURE

SCREW

 

SCREW

 

DIAPHRAGM

"F"

DESIGNATION

IDLE MIXTURE

SCREW

MAIN MIXTURE SCREW

15

TROUBLESHOOTING CARBURETION

POINTS TO CHECK FOR CARBURETOR MALFUNCTION

TROUBLE

CORRECTIONS

 

 

Carburetor out of adjustment

3-4-11-12-13-15-20

Engine will not start

1-2-3-4-5-6-8-9-10-11-12-14-15-16-17-19-21-24-25

Engine will not accelerate

2-3-4-5-11-12-19-24

Engine hunts (at idle or high speed)

3-4-8-9-10-11-12-14-20-21-24-26-27

Engine will not idle

3-4-8-9-10-11-12-13-14-18-20-21-22-24-25-26-27

Engine lacks power at high speed

2-3-4-6-8-10-11-12-15-18-19-20-21-24-25-26

Carburetor floods

4-7-17-21-22-25-26

Carburetor leaks

4-6-7-10-17-18-23-24-25

Engine overspeeds

8-9-11-14-15-18-20

Idle speed is excessive

8-9-13-14-15-18-20-25-26-27

Choke does not open fully

8-9-14-15

Engine starves for fuel at high speed (leans out)

1-3-4-5-6-10-11-15-16-17-18-19-21-25-26

Carburetor runs rich with main adjustment

7-8-9-11-14-17-18-19-21-25-26

needle shut off

 

Performance unsatisfactory after being serviced1-

2-3-4-5-6-7-8-9-10-11-12-14-15-16-17-18-19-20-

 

21-24-25-26

 

 

1.Open fuel shut off valve at fuel tank. Fill tank with fresh clean fuel.

2.Check ignition, spark plug and compression.

3.Clean air cleaner service as required.

4.Dirt or restriction in fuel system clean tank and fuel strainers, check for kinks or sharp bends.

5.Check for stale fuel or water in fuel. Fill with fresh fuel/oil mixture of correct ratio.

6.Examine fuel line and pick-up for sealing at fittings.

7.Check and clean atmospheric vent holes.

8.Examine throttle and choke shafts for binding or excessive play remove all dirt or paint, replace shaft.

9.Examine throttle and choke return springs for operation.

10.Examine idle and main mixture adjustment screws and “O” rings for cracks or damage.

11.Adjust main mixture adjustment screw. Some models require finger tight adjustment. Check to see that it is the correct screw.

12.Adjust idle mixture adjustment screw. Check to see that it is the correct screw.

13.Adjust idle speed screw.

14.Check position of choke and throttle plates.

15.Adjust control cable or linkage to assure full choke and carburetor control.

16.Clean carburetor after removing all non-metallic parts that are serviceable. Trace all passages.

17.Check inlet needle and seat for condition and proper installation.

18.Check sealing of welch plugs, cups, plugs and gaskets.

19.Check fuel pump operation pump element, inner and outer one way valves.

20.Adjust governor linkage.

FLOAT CARBURETOR CHECKS

21.Adjust float setting.

22.Check float shaft for wear and float for leaks or dents.

23.Check seal for fuel drain or bowl gasket.

24.Is carburetor operating at excessive angle?

CHECKS FOR DIAPHRAGM

25.Check diaphragm for cracks or distortion and check nylon check ball for function.

26.Check sequence of gasket and diaphragm for the particular carburetor being repaired.

27.Check spring tension on idle governor (if present).

16

STANDARD SERVICE CARBURETORS

FUEL FITTING

NOTE: MOST service carburetors are marked “SVC CARB NF” in the Price List. This means that the carburetor comes with NO FUEL FITTING.

Use the parts manual to obtain the same fuel inlet fitting that was installed in the original carburetor. Install the fuel fitting in the new carburetor body in the same position as on the original carburetor. Support the carburetor body with a wood block to avoid damage to other parts. Use a bench vise or press to install the fitting squarely. Press it in until it bottoms out.

NOTE: PRESS FUEL FITTING IN SQUARELY USING CAUTION SO THAT THE CARBURETOR BODY IS NOT DAMAGED.

INLET FUEL FITTING

To remove a leaking or damaged fuel inlet fitting, use a 1/4"(6 mm) bolt, 1/4" (6 mm) nut and 1/4" (6 mm) washer, along with a 1/2" (12 mm) nut. Use a pliers or vise to remove the plastic part of the inlet fitting. Tap the inside of the remaining metal portion of the fitting using a 1/4"- 20 (6 mm) tap. Place a 1/2" (12 mm) nut over the fuel fitting (it may be necessary to guide one side of the nut to seat it squarely to the carburetor). Next thread the 1/4" (6 mm) nut on the bolt until it contacts the shank, add the washer, and thread the bolt into the fitting until snug. Tighten the 1/4"-20 (6 mm) nut until the fitting is removed.

CHOKE SHAFT

NOTE: Never reuse choke or throttle shutter screws, always replace with new Tecumseh service screws part number 650506.

Remove the choke shutter screw from the original carburetor and remove the choke shaft. Observe the position of the ends of the choke return spring if one is present. Also observe the position of the cut-out and/or holes in choke shutter. Some chokes turn clockwise and some turn counterclockwise, note the position of the choke shaft prior to removal from the old carburetor.

If a choke stop spring is present on the new carburetor and is not used on the old carburetor, cut it off with a side cutter or pull it out using a pliers.

Test the action of choke shaft to make sure it moves freely and easily and does not bind in either open or closed position. If binding occurs, loosen the shutter screw; reposition the shutter and tighten the screw.

THROTTLE LEVER

Remove the throttle lever and spring and file off the peened end of the throttle shaft until the lever can be removed. Install the throttle spring and lever on the new carburetor with the self-tapping screw furnished. If dust seals are furnished, install them under the return spring.

IDLE SPEED ADJUSTMENT SCREW

Remove the screw assembly from the original carburetor and install it in the new carburetor. Turn it in until it contacts the throttle lever. Then an additional 1 turn for a static setting.

FLOAT TYPE CARBURETOR

CHOKE SHAFT

SELF TAPPING SCREW

IDLE CRACK

LEVER

SCREW AND

 

SPRING

SPRING

 

 

 

SPRING

WASHER

WASHER

FELT SEAL

FELT SEAL

THROTTLE SHAFT

 

CHOKE STOP

 

SPRING

 

SHUTTER

 

 

SHANK

 

SCREW

FUEL FITTING

 

 

 

 

 

 

"O" RING

 

 

 

SEAT AND CLIP

 

 

 

INLET NEEDLE

 

 

 

SPRING CLIP

FLOAT

 

 

 

 

FLOAT SHAFT

 

 

 

FLOAT BOWL

 

 

 

BOWL NUT WASHER

 

 

 

HIGH SPEED BOWL NUT

DIAPHRAGM TYPE CARBURETOR

THROTTLE LEVER

AND SHAFT

SPRING

CHOKE LEVER

AND SHAFT

WASHER

 

 

FELT SEAL

FUEL INLET

THROTTLE SHUTTER

 

 

SHUTTER SCREW

 

 

IDLE ADJUSTMENT

 

 

SCREW

 

 

CHOKE

 

 

 

 

 

 

SHUTTER

SEAL

 

 

 

WASHER

 

 

SHUTTER

 

 

 

SPRING

 

 

SCREW

LOW SPEED

HIGH SPEED

 

 

ADJUSTMENT

ADJUSTMENT

 

 

SCREW

SCREW

DIAPHRAGM

 

 

 

 

DIAPHRAGM

 

 

GASKET

 

 

DIAPHRAGM

 

 

 

COVER

PRIMER FITTING

 

DIAPHRAGM

 

 

COVER SCREW

17

GOVERNORS AND LINKAGE

AIR VANE GOVERNORS. All Tecumseh 2 cycle engines covered in this book are equipped with pneumatic (air vane) governors. The governor's function is to maintain a R.P.M. setting when engine loads are added or taken away. Air vane governors are controlled by the air velocity created by fins on the flywheel. Changes in the engine R.P.M. cause the air vane to move. The throttle is opened as the engine R.P.M. drops and is closed as the engine load is removed.

OPERATION

Engine R.P.M. changes cause an increase or decrease in the air velocity created by the fins on the flywheel. The air velocity exerts pressure on the air vane while a governor spring exerts pressure against the air velocity force. The air vane pivots on the engine flange or is attached to the throttle shaft of the carburetor. As an engine load is applied and the engine's R.P.M drop, the air velocity also drops, allowing the governor spring to pull open the throttle shaft and increase engine speed.

LINKAGE INSTALLATION. The best method is to record the linkage attachment points prior to disassembly and reinstall the same way.

Illustrations showing most governor and linkage hookups are pictured in this section. Select the diagram that resembles the engine you are servicing. R.P.M. settings may be found in microfiche catalog, card number 30.

AIR VANE

SLEEVE

TABS

Rotate sleeve clockwise to increase R.P.M.; counterclockwise to decrease R.P.M.

NOTE: The sleeve is serrated to rotate in a clockwise direction and must be raised using the sleeve tabs before it can be rotated counterclockwise.

To disassemble, remove choke shutter with needle- nose pliers; the vane assembly may then be removed from the carburetor.

AIR VANE

ASSEMBLY

BEND TAB TO

ADJUST RPM

HORIZONTAL FIXED SPEED

PLASTIC AIR VANE GOVERNOR

18

ADJUST RPM BY LOOSENING SCREW AND SLIDING BRACKET Ó È DECREASEINCREASE

HORIZONTAL FIXED SPEED

IDLE RPM ADJUSTMENT

IDLE

MIXTURE

HIGH SPEED

RPM

ADJUSTMENT

THIS HOLE NOT PRESENT ON ALL

MODELS SPRING

(ALUMINUM AIR VANE GOVERNOR)

VERTICAL ENGINE

VARIABLE SPEED-REMOTE CONTROL

ADJUST RPM BY LOOSENING SCREW AND SLIDING BRACKET Ó È DECREASEINCREASE

SPRING

GOVERNOR

LINK

IDLE RPM

ADJUSTMENT

IDLE MIXTURE

THIS HOLE NOT

PRESENT ON ALL MODELS

HORIZONTAL FIXED SPEED

VERTICAL ENGINE

FIXED SPEED-REMOTE CONTROL

IDLE RPM

ADJUSTMENTS

VERTICAL ENGINE

VARIABLE SPEED

MANUAL CONTROL

HIGH SPEED RPM ADJUSTMENT

THIS HOLE NOT PRESENT ON ALL MODELS

SPRING

THIS HOLE NOT

PRESENT ON ALL MODELS

SPRING

RPM ADJUSTMENT

VERTICAL ENGINE FIXED SPEED

19

REWIND STARTERS, ELECTRIC STARTERS AND

ALTERNATORS

REWIND STARTERS

GENERAL INFORMATION

Rewind starters used on vertical shaft Tecumseh engines are top mount horizontal pull style or side mount vertical pull style. Horizontal shaft engines use side mounted starters which can be mounted to pull either vertically or horizontally. All rewind starters except the vertical pull style turn the engine over by engaging a dog(s) into the starter cup attached to the engine flywheel. The vertical pull starter engages the starter gear into the ring gear of the flywheel to turn the engine over. All starters are spring loaded to retract the dog(s) or starter gear when the engine speed exceeds the turning speed of the starter.

OPERATION

As the starter rope is pulled, the starter pulley rotates on the center pin. The starter dog(s) is pinned or pocketed in the pulley hub and extends outward when the pulley's rotation forces the starter dog(s) to contact the ears on the retainer. The retainer ears act as a ramp to fully extend the starter dog(s). The fully extended starter dog(s) locks in contact with notches in the starter cup. When the engine fires and the rotational speed of the starter cup exceeds the starter pulley, the starter dog(s) disengages from the starter cup. The starter dog spring(s) returns the starter dog(s) to the disengaged position. The recoil spring turns the starter pulley in the opposite direction, retracting the starter rope until the handle contacts the stop.

COMPONENTS

SERVICE

Starter related problems will require the starter to be removed from the engine to diagnose the cause. Visually inspect the starter dog(s), starter cup, retainer, springs, rope, washers, and the starter pulley for wear or breakage. Use one of the following procedures that applies to your application, to disassemble, repair, and assemble the starter. Always consult the Tecumseh Master Parts Manual for the correct replacement parts.

ROPE SERVICE

Rope replacement should be done using the correct part number replacement rope or braided rope of the correct diameter and length. Consult the Tecumseh Master Parts Manual to obtain the correct part number, length, and size required. Use the following rope chart to convert a numbered rope to a fractional diameter for bulk rope use.

# 4 1/2 rope = 9/64" (3.572 mm) diameter

Part No. 730526 -100' (30.48 meters) spool

# 5 rope = 5/32" (3.964 mm) diameter

Part No. 730514 - 100' (30.48 meters) spool

# 6 rope = 3/16" (4.762 mm) diameter

Part No. 730516 - 100' (30.48 meters) spool

Standard rope lengths

54" (16.5 meters) standard stamped steel starter

HANDLE

STARTER HOUSING

61" (18.6 meters) vertical pull - horizontal engagement type

65" (20 meters) vertical pull - vertical engagement

type

ROPE

PULLEY AND REWIND

SPRING ASSY.

STARTER DOG

DOG SPRING

WASHER RETAINER

85" (26 meters) extended handlebar rope start

(compliance)

Check the old rope for the right length for the application. Some applications require longer lengths. The rope ends should be cauterized by burning with a match and wiping the rope end with a cloth while hot.

Rope replacement can be done without the starter being disassembled on vertical pull starters that have "V"

BRAKE SPRING WASHER

SPRING PIN

notches in the bracket. Use the following procedure for rope replacement.

1.Remove the starter assembly from the engine.

2.Turn the pulley until the staple in the pulley lines up with the "V" notch. Pry out the staple with a small screwdriver and remove the original rope.

20

3.Turn the pulley counterclockwise to fully wind the starter return spring until tight. Allow the pulley to unwind until the hole in the pulley lines up with the "V" notch.

4.Hold the pulley in this position and feed the new rope through the hole and tie a left-handed knot on the rope end. Make sure the rope and knot do not protrude from the knot cavity and bind the pulley rotation.

LEFT-HAND

KNOT

RETAINER REPLACEMENT

1.Remove the starter handle if the retainer is a complete circle design. Remove the staple and old retainer.

2.Slide the rope retainer into the proper position and insert the staple using a pliers.

3.Install the starter handle and tie a left hand knot to secure the handle.

4.Remove the brake spring, spring retainer, washers, and pulley assembly (diag. 7, 8, 9 & 10)

NOTE: The starter dogs face out on the stamped steel starter and the dogs face in on the stylized rewind starter.

5.All components in need of service should be replaced.

HANDLE

STARTER

HOUSING

 

 

ROPE

PULLEY AND REWIND

SPRING ASSY.

DOG SPRING

STARTER DOG

WASHER

RETAINER

BRAKE SPRING

WASHER

SPRING PIN

ONE PIECE ROPE RETAINER

STYLIZED REWIND STARTER

Disassembly Procedure

1.After removing the rewind assembly from the engine blower housing, release the tension on the rewind spring. This can be done by removing the starter handle and carefully allowing the rope to unwind in the starter housing assembly.

2.Place a 1" (25 mm) deep well socket under the retainer. Set the rewind on a bench, supported on the socket.

3.Use a 5/16" (7.938 mm) or 1/4" (6.35 mm) (for stamped steel) roll pin punch to drive out the center pin. The stamped steel center pin is driven out from the top, inside the center hole. Move the punch around while driving the pin to help keep the pin straight.

CAUTION: THIS REWIND SPRING IS NOT SECURED IN A CANISTER. PULLEY BOSSES HOLD THE REWIND SPRING AND COVER, AND CAN BE EASILY DISLODGED DURING HANDLING.

21

ASSEMBLY PROCEDURE

NOTE: It is critical to support the starter on a deep well socket to prevent damage.

1.Reverse the disassembly procedure. The starter dogs with the dog springs must snap back to the center of the pulley (disengaged position). When the rope is pulled, the tabs on the retainer must be positioned so that they will force the starter dogs to engage the starter cup. (diag. 7 & 8)

2.Always replace the center spring pin with a new one upon reassembly. Place the two new plastic washers between the center leg of the starter and the retainer. New plastic washers are provided with a new center spring pin. Discard the old plastic washer.

3.Place the rewind on a flat surface and drive the new center pin in until it is within 1/8" (3.175 mm) of the top of the starter.

NOTE: DO NOT DRIVE THE CENTER PIN IN TOO FAR.

The retainer will bend and the starter dogs will not engage the starter cup. On the stamped steel starter the center pin should be driven in until it contacts the shoulder in the starter body.

4.Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring, thread the rope through the starter housing eyelet and tie a temporary knot in the rope. Reattach the starter handle to the rope using a left-hand knot. Untie the temporary knot and allow the rope to recoil.

 

 

 

HOUSING

HANDLE ASSY.

 

 

 

 

SPRING & KEEPER

 

 

 

ASSY.

 

ROPE

 

 

 

 

PULLEY

BRAKE SPRING

DOG SPRING

 

 

 

 

DOG

BRAKE SPRING

 

RETAINER

 

 

 

 

 

RETAINER SCREW

STARTER DOG

 

 

 

 

 

 

 

HOLE IN PULLEY

EYELET

VERTICAL PULL STARTER HORIZONTAL ENGAGEMENT TYPE

DISASSEMBLY PROCEDURE

1.Remove the handle and relieve the starter spring tension by allowing the rope to slip past the rope clip.

2.Remove the spring cover by carefully removing the two small screws. Carefully take out the spring.

3.Remove the center hub screw and the spring hub.

4.Lift off the gear and pulley assembly. Disassemble the pulley assembly by removing the snap ring and washer (diag. 13).

5.Remove the starter rope if necessary. Replace all worn or damaged parts.

HANDLE

 

ROPE

SCREW

 

ROPE CLIP

 

 

 

 

 

 

 

GEAR

 

 

COVER

 

AND

 

 

SCREW

 

 

THRUSTBRAKE

 

MOUNTING

SNAP

 

PULLEYSPRING

SPRING

 

 

BRACKET

 

SPRING

 

 

 

 

 

 

 

 

 

 

WASHER

 

HUB

 

 

 

SCREW

 

 

 

 

 

 

 

22

Assembly Procedure

1.Insert the rope through the starter pulley.

2.Assemble the gear, pulley, washer, and snap ring.

3.Place a small amount of grease on the center shaft, place the gear and pulley into position making sure the brake spring loop is positioned over the metal tab on the bracket. The rope clip must fit tightly onto the bracket. The raised section fits into the hole in the bracket.

4.Install the hub and hub screw. Torque the hub screw to 45 - 55 in. lbs. (5 - 6 Nm). A loose hub screw will prevent the rope from retracting.

5.Install the return spring if necessary. A replacement spring is installed by placing the spring and its retainer over the top of the pulley and pushing the spring out of the retainer into the pulley's recessed area.

6.Install the spring cover and the cover screws.

7.Wind the rope onto the pulley by slipping it past the rope clip. When the rope is fully wound on the pulley, wind the pulley assembly two additional turns to put tension on the spring.

8.Mount the starter on the engine making sure the top of the starter gear teeth are no closer than 1/16" (1.59 mm) from the top of the flywheel ring gear teeth.

 

LEFT-HAND

 

KNOT

RECEPTACLE

MOUNTING BRACKET

FOR RAISED

TAB MUST FIT INTO

SECTION

SPRING LOOP

RAISED SPOT

BRAKE

ROPE CLIP

STYLIZED REWIND STARTER WITH PLASTIC RETAINER

DISASSEMBLY PROCEDURE

1.After removing the rewind assembly from the engine blower housing, remove the starter handle by first pulling a length of rope out using the handle, tying a temporary knot in the exposed rope, and either untying the knot in handle or prying out the staple.

2.Untie the temporary knot and slowly allow the rope to fully retract into the starter housing and the recoil spring to fully unwind.

3.Remove the decal from the center of the starter housing.

4.Use a small Phillips screwdriver or similar tool to pry the retainer legs apart and lift out the retaining wedge.

5.Pinch the legs of the retainer together and pull on the head of the retainer to remove it from the housing.

6.Remove the pulley assembly from the recoil housing.

7.Repair or replace as necessary.

RETAINER WEDGE

STARTER

HOUSING

STARTER PULLEY

SPRING & COVER

DOG SPRING

STARTER DOG

DOG RETAINER

ASSEMBLY

1.If replacing the starter rope, see Step 8.

2.Install a new recoil spring if necessary by pushing the new spring out of the holder into the pulley cavity while aligning the outside spring hook into the deep notch in the pulley. Push the spring cover in until seated.

3.Apply a small amount of lithium grease to the inner bore of the center shaft.

4.Replace or check that both starter dogs are in the pulley pockets and that the dog springs are hooked on the outer surface of the dog.

23

5.Pinch the two legs of the plastic retainer together and start into the center shaft hole.

6.Rotate the retainer so the two tabs on the bottom of the part fit between the dog and pulley hub (left side of the dog). Push the retainer in until the leg prongs pop out of the center shaft.

7.Turn the starter over and snap the locking tab between the retainer legs, replace the top decal.

NOTE: Refer to Service Bulletin 122 for metal locking tab.

8.Wind the starter pulley counterclockwise four or five turns to pre-load the recoil spring and thread the rope through the starter housing eyelet. Pull enough rope through to tie a temporary knot in the rope. Reattach the starter handle to the rope using a left-hand knot. Untie the temporary knot and allow the rope to recoil.

VERTICAL PULL STARTER, VERTICAL ENGAGEMENT TYPE

DISASSEMBLY PROCEDURE

1.Pull out enough rope to lock the rope in the "V" of the bracket.

2.Remove the handle if necessary by prying out the small staple in the handle with a screwdriver.

3.Place the starter bracket on the top of a deep well socket that is large enough to receive the head of the center pin. Use an arbor press to drive out the center pin.

4.Rotate the spring capsule strut until it is aligned with the legs of the brake spring. Insert a nail or pin no longer than 3/4" (19.05 mm) through the hole in the strut so it catches in the gear teeth. This will keep the capsule in the wound position.

5.Slip the sheave out of the bracket.

CAUTION: DO NOT ATTEMPT TO REMOVE THE SPRING CAPSULE FROM THE SHEAVE ASSEMBLY UNLESS THE SPRING IS FULLY UNWOUND.

6.Squeeze and hold tightly by hand the spring capsule at the outer edge against the gear sheave.

7.Remove the retainer pin from the strut and slowly relieve the spring tension by allowing the spring capsule to rotate slowly under control, until completely unwound. The spring capsule can now be removed from the gear sheave.

ROTATE

COUNTERCLOCKWISE

STRUT PIN

ASSEMBLY PROCEDURE

1.Feed the new rope through the hole and tie a left- handed knot on the rope end. Make sure the rope and knot do not protrude from the knot cavity and bind the pulley rotation.

ORIGINAL INSTALLATION WITH STAPLE

INSTALL NEW

LEFT-HAND

KNOT

ROPE BY TYING

 

LEFT-HAND

 

KNOT

 

REINSTALL

PRY STAPLE

OUT TO

LEFT-HANDED

REMOVE OLD

KNOT

ROPE

2.Wind the rope on the sheave assembly clockwise, viewing the gear from the gear side of the sheave.

3.Reinstall the brake spring, being careful not to spread the spring more than necessary.

4.Install the spring capsule, making sure the starter spring end hooks on the gear hub.

5.Wind the spring four full turns and align the brake spring legs with the strut as shown. Insert the pin in the strut.

GEAR HUB

STARTER SPRING

END

SPRING HOOKED ON

ROTATE SPRING

GEAR HUB

 

4 FULL TURNS

24

6.If the starter is equipped with a locking or delay pawl and spring, make sure these are in place before grasping the gear and spring capsule assembly and sliding it into the bracket. Make sure the legs of the brake spring are positioned in the slots of the bracket.

7.Feed the rope end under the rope guide and hook it into the "V" notch. Remove the pin and the strut will rotate clockwise against the bracket.

8.Insert the new center pin by pressing or driving the pin firmly in place. Reinstall the starter assembly on the engine.

 

STARTER HANDLE

 

ROPE

BRAKE

PULLEY

 

SPRING

PAWL SPRING *

ASSY.

 

CLIP *

 

KEY*

STRUT

 

ROPE CLIP

PAWL

 

BRACKET

LOCKING PAWL*

PIN

 

"V"ROPE WEDGE

 

* USED ON SOME MODELS

 

HANDLE INSERT

HANDLE

STARTER ROPE

REWIND SPRING

PULLEY

RETURN SPRING

STARTER DOG

HOUSING

ASSY.BRAKE

BRAKE SPRING

TRUARC

 

 

"E" CLIP

ASSEMBLY PROCEDURE.

1.Hook loop of spring into housing and wind in housing in a counterclockwise direction. The spring should have a light coating of grease on it.

2.Place pulley into housing.

3.Install dog spring and dog in starter pulley in the socket closest to the rope hole in pulley.

4.Replace brake spring, brake and install “E” clip.

5.To put tension on spring, wind pulley counterclockwise until tight, then allow to unwind until the hole in the pulley lines up with the eyelet in housing, then install rope and handle.

GUIDE BRAKE ENDS

WHEN PIN IS REMOVED STRUT

THROUGH SLOT

WILL ROTATE 45o CLOCKWISE

 

 

REWIND STARTER MOUNTED IN HOUSING DISASSEMBLY PROCEDURE.

1.Pull rope out to untie knot in rope and slowly release spring tension.

2.Remove “E” clip, brake, brake spring, starter dog and return spring.

3.Lift out pulley; rewind spring is located in the housing. Replace all worn or damaged parts.

25

ELECTRIC STARTERS

The following electric starter illustrations will not be identical in configuration to the starter being serviced, but tests apply unless otherwise stated. Starters labeled CSA cannot be serviced, except for external components.

The following starter, number 590556, is a sealed UL and CSA approved starter, and the only component that can be serviced is the drive assembly.

 

END CAP

 

BRUSHES

BRUSH SPRINGS

BOLT

NUTS

 

WASHER

THRUST WASHER

BRUSH BRUSH

CARD SPRINGS

HOUSING

 

 

RETAINER

 

 

RING

 

SPRING

 

ARMATURE

GEAR

 

 

 

 

LOCKNUT

 

 

 

 

 

 

SPRING RETAINER

 

ENGAGING NUT

DRIVE ASSEMBLY SERVICE. Pinion gear parts should be checked for damage or wear. If the gear sticks on the shaft, it should be washed in solvent to remove dirt and grease, then dried thoroughly. If damaged, replace with new parts.

On units with the gear under the cap assembly, use the following procedure for disassembly:

1.Remove retainer ring from armature shaft.

2.Remove the two nuts from the through bolts holding on the cap assembly.

3.Slide off the cap assembly. The engaging nut, gear, spring and spring retainer will remain in the cap assembly.

4.Remove, inspect, and replace as necessary. Use reverse procedure for assembly.

ENGAGING NUT

ANTI DRIFT SPRING

SPRING RETAINER

DUST COVER

FRICTION

WASHER

 

 

GEAR

 

RETAINER RING

To disassemble the drive assembly, use the following procedure:

1.Remove plastic dust cover.

2.Push down spring retainer and remove retainer ring.

3.Slide off spring retainer, anti-drift spring, gear, friction washer, and engaging nut. Inspect and replace as necessary.

Use reverse procedure for assembly.

TORX® E8

HEAD SCREW

The 590556 Electric Starter uses a mounting screw with a Torx® E-8 head. To torque this screw you must use a 670307 Torx® E-8 socket.

26

STARTER CHECKING AND SERVICE. Remove nuts at both ends of the starter and take off rear end cap.

CHECK BRUSHES. Before removing the armature, check brushes for wear. Make sure brushes are not worn to the point where the brush wire bottoms out in the slot of the brush holder. Brush springs must have enough strength to keep tension on the brushes and hold them against the commutator.

If brushes need replacement, remove by unhooking the terminals or cutting the connections and then resoldering. If the brush card is warped from overheating, replace the card assembly.

FIELD COIL

CONNECTORS

CONNECTION POINTS

OF POWER CORD LEADS

CHECK FIELD. Using a continuity light or ohmmeter, check the field by attaching one lead to each field coil connection. Continuity should exist between these two points. Check continuity between each field coil connection and the starter housing. No continuity should exist.

ARMATURE CHECK. If the commutator bars are glazed or dirty they can be turned down on a lathe. While rotating, hold a strip of 00 sandpaper lightly on the commutator, and moving it back and forth. (Do not use emery cloth). Recut the grooves between the commutator bars to a depth equal to the width of the insulators.

Use a continuity tester to make certain no continuity exists between the commutator (copper) and the iron core of the armature, rotate armature and check out all commutator bars.

The armature can be thoroughly checked with a growler if available.

TROUBLESHOOTING STARTERS.

STARTER DOES NOT FUNCTION. Check for:

1.No current to the starter caused by faulty connections or blown circuit breaker.

2.Faulty safety switches, ignition, starter switch, or solenoid.

3.Engine locked up or parasitic load on engine.

4.Shorted, open, or grounded field coil.

5.Open, shorted, or bent armature.

6.Brushes sticking or damaged.

7.Dirty or oily brushes or commutator.

STARTER CRANKS ENGINE SLOWLY. Check for:

1.Parasitic load or “tight” engine.

2.Worn brushes or weak brush springs.

3.Dirty, oily, or worn commutator.

4.Worn bearings in cap assemblies.

5.Defective armature.

STARTER SPINS, ENGINE DOES NOT CRANK. Check for:

1.Pinion gear sticking on shaft.

2.Damaged pinion or flywheel ring gear.

27

ALTERNATORS

Some engines are equipped with an alternator and regulator to supply current to power head lights, tail lights, etc. on recreation vehicles. Shown here is a typical wiring diagram.

HEAD & TAIL LIGHT

STOP LIGHT

(MOUNTED ON BLOWER HOUSING OR COVER PLATE)

TYPE A

RED

-LEAD

MAGNETO GROUND SWITCH

MAGNETO GROUND

OHM METER

LIGHT

STOP LIGHT SWITCH

(MOUNTED ON BLOWER HOUSING)

SWITCH

HEAD LIGHT

TAIL STOP LIGHT

VIEW FROM BOTTOM

CHECKING THE SYSTEM. At an idle speed (2600 R.P.M.) a slight dimming of the lights will be noticed, This is normal and should not be considered faulty.

Before going into extensive checks, be sure to examine the more basic causes first, such as:

1.Make sure bulbs are good and the right ones are being used. Number 1157 for tail & stop light; 4416 or 4420 for head lights.

2.Corroded terminals.

3.Cracked wire insulation.

4.Broken wires.

5.Broken wires covered by insulation.

6.A wire grounding out the system.

7.Loose connections.

8.Make sure regulator has good ground.

9.Faulty Switch.

Check the regulator for resistance. If regulator checks out and all bulbs and wiring are ok, replace alternator coils.

Three types of regulators have been utilized. Use the ohm readings in the chart below for the type that you are servicing. Readings should be as follows:

Type A

Type B

Type C

 

 

 

100 to 200

Over 50,000

100 to 200

Ohms

Ohms

Ohms

 

 

 

TYPE TYPE C

B

RED LEAD

VIEW FROM BOTTOM

OHM METER

28

FLYWHEEL (INSIDE-EDGE) BRAKE SYSTEM

Tecumseh’s brake systems provide two methods of meeting compliance standards which has become a Federal law as of June 30, 1982. There are two additional methods used by equipment manufacturers that also meet compliance standards, they are:

1.Use of the blade brake clutch in conjunction with either a top or side mounted recoil starter. The blade stops within three seconds after the operator lets go of the blade control bail at the operator position and the engine continues to run. Starter rope handle is on the engine.

2.Use of a recoil starter (top or side mounted) with the rope handle on the engine as opposed to within 24 inches from the operator position. This method is acceptable if the mower deck passes the 360 degree foot probe test. A specified foot probe must not contact the blade when applied completely around the entire blade housing. This alternative can be used with engine mounted brake systems and typical bail controls. The blade stops within three seconds after the operator lets go of the blade control bail at the operator position and the engine is stopped.

Tecumseh’s Flywheel (Inside-Edge) Brake System provides consumer safety by shutting down the engine and lawnmower blade within seconds after the operator releases the Engine/Blade control at the handle of the lawnmower.

INSIDE EDGE SYSTEM

In the stop position the brake pad is applied to the inside edge of the flywheel, at the same time the ignition system is grounded.

In order to restart the engine, the brake control must be applied. This action pulls the brake pad away from the inside edge of the flywheel and opens the ignition kill switch. On electric start systems the starter is energized by an ignition switch or a two motion control. On non-electric start systems, the recoil starter rope must be pulled to start engine.

COMPONENTS

The Inside Edge system uses the following components:

The brake lever and pad assembly consists of a steel lever with a brake pad bonded to the lever.

The ignition kill switch is a plastic block with a wire extending out of it. The wire is attached to a terminal which is connected to the ignition kill wire. The brake lever contacts and grounds the wire of the switch when the engine / blade control is released, and the ignition module is grounded. This in turn kills the ignition.

The interlock switch is a push button switch that is activated by the brake lever when the engine / blade control is actuated. If there is a starter switch used to start the engine, the interlock switch acts as a safety switch and will not allow the starter to crank unless the engine / blade control is depressed.

Where a two motion control is used the interlock switch is utilized as the starter switch.

The Torsion Spring supplies the pressure to the brake lever and brake pad to stop the flywheel.

The Control Cable transfers the motion of the engine / blade control to the brake system.

SERVICE

If the brake system fails to kill the ignition and stop the blade within 3 seconds the following service procedures should be followed.

Remove the flywheel as outlined in "IGNITION" section.

NOTE: BEFORE THE FLYWHEEL IS REMOVED OR REPLACED, THE BRAKE PRESSURE ON THE FLYWHEEL MUST BE RE-LEVELED AS OUTLINED.

IGNITION SHORTED

BRAKE APPLIED

 

 

IGNITION OPEN

BRAKE RELEASED

29

INSIDE EDGE

To relieve the brake pressure on the flywheel, compress the spring by moving the lever toward the spark plug, when the hole in the lever aligns with the hole in the bracket, secure the lever with alignment tool 670298 then remove the flywheel (diag. 7). Remove the alignment tool. Release the spring tension by unhooking the short end of the spring from bracket with a pliers. Remove the “E” clip from the brake pad shaft. Slide the pad lever from the shaft and unhook the link. Inspect the brake pad for dirt, oil or grease contamination. If the pad is contaminated, or if there is less than .060" (1.524

mm)of brake pad material at the pad's thinnest point, replacement is necessary. The brake pad is bonded to the brake lever and must be replaced as an assembly. Rehook the link, install the brake lever and pad assembly, install the "E" clip, rehook the short end of the spring and continue to reassemble the brake system in the reverse order of disassembly.

SHORT END OF SPRING

ALIGN HOLES

SWITCH

LEVER670298

IGNITION GROUND OUT TERMINAL

Inspect the ignition kill switch grounding clip for proper alignment and contact with the brake arm. Insure that all electrical connections are clean and secure.

GROUNDING CLIP

GROUNDING CLIP POSITION

LINKAGE

"E" CLIP

BRAKE PAD

 

STARTER INTERLOCK SWITCH

The engine / blade control must close the interlock switch before the starter can be engaged. To check the interlock switch, use an ohmmeter or continuity light to perform a continuity check. Continuity should exist between the two terminals when the interlock switch button is completely depressed. No continuity should exist when the button is released. If the switch fails replace the switch.

To replace the interlock switch, carefully grind the heads off of the rivets that fasten the interlock switch to the brake bracket. Remove the rivets from the back side of brake bracket. Use the self-tapping screw supplied with the new switch to make threads in the bracket. Install the interlock switch onto the brake bracket in the proper position and secure the switch to the brake bracket with the machine screws supplied. Be careful not to overtighten the screws as switch breakage can occur.

SELF TAPPING

SCREW

MACHINE

SCREWS

CONTROL CABLE

INSIDE EDGE

If replacing the cable conduit screw with a screw other than a service part replacement, be certain that the screw length is not too long as to prevent free travel of the lever. Make sure the button on the starter interlock switch is completely depressed when the control is fully applied. The cable must provide enough travel so the brake will contact the flywheel. Some slack should exist in the cable adjustment to compensate for brake pad wear.

SCREW END MUST

CABLE CLAMP

NOT BLOCK LEVER

SCREW

ACTION

 

When installing a inside edge brake bracket assembly, be sure the slotted holes in the brake bracket are all the way down on the fasteners. This will properly align the brake bracket to the flywheel brake surface.

MOUNTING HOLES

Ô

Ô

MECHANISM FULL DOWN

BEFORE SCREWS TORQUED

30

IGNITION

IGNITION OPERATION

(PRE-1985 Production)

PATH OF MAGNET LINES OF FORCE

MAGNETO IGNITION. Tecumseh’s magneto ignition consists of a stator assembly made up of a coil, laminations, contact points, condenser, and a permanent magnet mounted in the flywheel of the engine.

COIL: The coil consists of a primary and a secondary winding of wire. The primary is the low voltage (200- 300 volts) primary winding consists of about 150 turns of heavy gage wire next to the core. One end of the primary is connected to the insulated contact point and the other end is grounded to the stator body.

The secondary winding consists of extremely fine wire with many turns (about 10,000) wrapped over the primary windings. One end connects to the spark plug and the other end is grounded to the stator body.

The coil is used as a transformer to increase the primary voltage to a high voltage (10,000 - 20,000 volts) which jumps across the spark plug gap.

FLYWHEEL ROTATION

PRIMARY

WINDING

POINTS

MAGNETCLOSED

SECONDARY

 

 

LEAD

PRIMARY LEAD

 

SECONDARY

 

 

WINDING

 

 

 

 

PRIMARY

 

 

GROUND

PRIMARY

 

LEAD

 

 

WINDING

 

 

 

 

GROUND LEAD

 

SECONDARY

TERMINAL

 

GROUND LEAD

FOR PRIMARY

 

 

AND SECONDARY

*The actual connection of the primary and secondary ground is normally made inside of *the coil, but it is shown above to illustrate the individual wires.

CONTACT POINTS. The contact points consist of an insulated movable point that connects to the coil primary lead and a stationary point that is grounded to the stator body which provides the return path for the primary circuit.

CONDENSER. The condenser acts as an electrical shock absorber to prevent arcing between the contact points as they open. Arcing lowers the voltage at the spark plug, as well as burn and pit the contact points, thus shortening point life.

OPERATION OF THE TECUMSEH MAGNETO IGNITION. As the flywheel turns, the magnets (mounted in the wheel) pass the coil mounted on the stator. As the magnet’s North Pole enters the area of the center leg of the stator, a magnetic field is concentrated through the laminations to the magnet’s South Pole. This causes a generation of current flow in the coil’s primary winding. The ignition points are closed.

As the flywheel continues to rotate, the North Pole approaches the last leg of the lamination stack. The magnetic field through the center leg reverses, producing a large change in the magnetic field and a high current in the primary windings of the coil.

At this time, the contacts open and the primary current stops flowing. This change in current causes a voltage in the primary windings, which induces the high voltage in the secondary winding of the coil. The voltage is routed through the spark plug wire, to the spark plug, and then jumps the gap of the plug to ignite the fuel air mixture.

POINTS OPEN

31

1985 to Present

SOLID STATE IGNITION. Tecumseh’s solid state capacitor discharge ignition (CDI) is an all electronic ignition system and is encapsulated in epoxy for protection against dirt and moisture.

SOLID STATE IGNITION OPERATION. As the magnets in the flywheel rotate past the charge coil, electrical energy is produced in the module. This energy is transferred to a capacitor where it is stored until it is needed to fire the spark plug.

The magnet continues rotating past a trigger coil where a low voltage signal is produced and closes an electronic switch (SCR).

The energy which was stored in the capacitor is now transferred through the switch (SCR) to a transformer where the voltage is increased from 200 volts to 25,000 volts. This voltage is transferred by means of the high tension lead to the spark plug, where it arcs across the electrode of the spark plug and ignites the fuel- air mixture.

32

IGNITION SERVICE

SPARK PLUG SERVICE. Spark plugs should be cleaned and adjusted periodically. Check point gap with wire feeler gauge (.030" - .762 mm) and adjust gap. Replace if points are pitted and burned or the porcelain is cracked. Refer to Master Parts Manual or Micro-Fiche for correct replacement number.

If spark plug fouls frequently, check for the following conditions:

1.Carburetor set too rich.

2.Choke not opening fully.

3.Poor grade gasoline.

4.Clogged exhaust system.

5.Incorrect spark plug.

6.Improper oil fuel ratio.

7.Inconsistent spark.

NOTE: Ensure cleaned spark plugs are free of all foreign material before installation.

FLYWHEEL REMOVAL AND SERVICE. To remove flywheel, use a strap wrench Part No. 670305 to hold the flywheel and remove the nut by turning it in the direction opposite of crankshaft rotation.

STRAP WRENCH 670305

NOTE: Do not attempt to remove flywheel using a jaw type pullers on the outer diameter of the flywheel or flywheel breakage will occur.

On engines with cored holes (not tapped) use flywheel puller part No. 670306.

FLYWHEEL PULLER 670306

NOTE: A KNOCK-OFF TOOL IS NOT RECOMMENDED FOR ENGINES WITH A BALL BEARING ON THE MAGNETO END OF THE CRANKSHAFT.

NOTE: If a knock-off tool is used, the pounding may cause the ball bearing to dislodge from the shroud base and force the lower thrust face of the crankshaft against the cylinder thrust face. TO CORRECT THIS CONDITION RAP SHARPLY WITH RAWHIDE MALLET ON THE P.T.O. END TO PROVIDE CLEARANCE BETWEEN CRANKSHAFT AND CYLINDER THRUST FACE.

BALL BEARING

MUST HAVE

CLEARANCE

If the flywheel is difficult to remove from the crankshaft because of rust, etc., the use of a propane torch can be helpful. Heat the area immediately outside of the crankshaft. The aluminum alloy in the flywheel should expand enough to break the seal away from the steel crankshaft.

FLYWHEEL MAGNETS. The magnets in the flywheel rarely lose their magnetic strength. If magnets are suspected to be faulty, place the flywheel upside down on a wooden surface. Hold a screwdriver by the extreme end of handle with the point down. Move the blade to within 3/4 inch of magnets. The magnets should attract the screwdriver blade against the magnet.

SCREWDRIVER LENGTH

 

APPROXIMATELY

 

6" (15.24 cm)

3/4" (19 mm)

MAGNETS

33

FLYWHEEL KEYS. The flywheel key locates the flywheel to the crankshaft in the proper position. If a flywheel key is sheared, or partially sheared, the engine will not start or may be difficult to start.

STEEL

ALUMINUM

 

ALLOY

CRANKSHAFT

GOLD

TIMING

SOLID STATE

TABS

IGNITION

NOTE: Use the Tecumseh Master Parts Manual to determine correct key for the application.

ADAPTER KEY TO FLYWHEEL ASSEMBLY. When an adapter is used, place the adapter with its raised key area in the flywheel keyway before putting the flywheel on the engine.

SLEEVE TO BE

PRESSED IN

FLUSH

WITH HUB

FLYWHEEL SLEEVE. Some engines utilize a sleeve between the crankshaft and flywheel which acts as a flywheel key. If this sleeve becomes sheared or damaged, replace. The flywheel sleeve is pressed into the crankshaft opening in the flywheel, and should be flush or slightly below flush from the inside surface of flywheel before in stalling on crankshaft.

For engines equipped with brake system, a new key and flywheel are shown. Torque procedures are the same.

NON-COMPLIANCE ENGINE

COMPLIANCE ENGINE

FLYWHEEL

 

SLEEVE

KEY

FLYWHEEL TORQUE. Torque flywheel to the proper specification. See the tables in specification section for the proper torque setting.

Loose lawn mower blades and adapters can contribute to sheared keys.

REPLACING MAGNETO BREAKER POINTS. Remove the nut holding the electrical leads to the screw on the movable portion of the breaker points.

Remove the screw from the stationary breaker point and remove point set. Reinstall the new breaker point set into position and adjust the point gap according to the specifications. Points must be adjusted, when the rubbing block of the points is on the highest spot on the breaker cam.

Clean points by putting lint-free paper between them and sliding it back and forth. Then open points and remove paper and any paper fiber remaining between the point set. Any oil, fingerprints or contamination will cause the points to burn prematurely.

CONDENSER CHECK. Check condenser on a good quality tester, following the test equipment manufacturer’s instructions to check capacity and resistance. Replace condenser if condition is questionable.

IGNITION COIL. Inspect the coil for cracks in insulation or other damage. Make sure electrical leads are intact, especially where they enter the coil.

Check operation of the coil using an approved tester following the instructions furnished with the test unit. If laminations are distorted or damaged, replace. Some coils are permanently attached to the laminations and must be serviced as an assembly.

IGNITION TIMING. Begin procedure by setting the point gap. This is done by rotating the crankshaft until the point arm is resting on the high side of the ignition cam. Set the point gap by loosening the screw on the movable point, and insert a feeler gauge per specification. Tighten the screw then recheck the gap.

CRANKSHAFT

CAM

ARM

POINTS

PIVOT

34

Install dial indicator (Part No. 670241) equipped with the correct tip on the extender leg. Use the small tip for engines with timing dimensions of between Top Dead Center and .050” (1.27 mm) BTDC . Use the large tip for engines with timing dimensions of between

.051" (1.29 mm) BTDC to .150” (3.81 mm) BTDC. Loosen the screw on the side of the adaptor sleeve to allow the sleeve to be turned into the threads of the spark plug hole, not the entire dial indicator. This will ensure the proper location of the tip. Once the adapter sleeve is secured in the hole, tighten screw on sleeve adaptor to prevent the dial from moving up or down, which would give a false reading.

T.D.C.

B.T.D.C.

While watching the needle on the dial indicator, rotate the crankshaft counterclockwise (when looking at the magneto end of the crank) past the specified Before Top Dead Center (BTDC) dimension. Then rotate the crankshaft back clockwise to the proper dimension, this will take out any slack between the connecting rod and crankshaft assembly.

(Using .080” (2.0 mm) BTDC dimension as an example.)

DIAL AT .090” (2.29 mm)

 

DIAL AT .080” (2.0 mm)

 

 

 

 

 

 

 

Find top dead center (TDC) by rotating the crankshaft clockwise (when looking at the magneto end of the crank) until the needle on the dial stops and reverses direction. Where the needle stops is TDC. Loosen the screw on the dial, and rotate the dial so that zero is lined-up with the needle at TDC. Tighten the screw on the dial to secure it in place.

DIAL SCREW

DIAL AT 0

Next, disconnect the leads from the point terminal, and be sure to reinstall the securing nut & tighten it up. Connect one lead of a continuity light, or Ohmmeter to the point terminal and the other lead to a good ground. Loosen the two bolts holding down the stator and rotate the stator until the continuity light or Ohmmeter indicates a break in the circuit. At this point torque down the stator bolts and the timing procedure is completed.

Before putting the dust cover back on the points box, clean the points by sliding lint free paper back and forth between the contacts. Manually, open the points when removing the paper to eliminate paper fibers from remaining between the contact points.

LINT FREE PAPER

35

FIXED TIME SYSTEM (External Coil). This system has the contact points and condenser mounted under the flywheel with the laminations and coil mounted outside the flywheel. This system is identified by the square hole in the stator, the round configuration of the coil, and a stepped flywheel key.

SOLID STATE (CDI). This is an all electronic ignition system with the components sealed in a module and located outside the flywheel.

A Solid State module can be identified by its square configuration, which will identify the need for the proper flywheel key or sleeve.

Begin the timing procedure, torque down the stator bolts to secure the stator in place. Next rotate the crankshaft until the point arm is resting on the high side of the ignition cam. Set the point gap at to the proper specification by loosening the screw on the movable point, and inserting a feeler gauge between the contact points. Tighten the screw on the movable point and then recheck the point gap. Be sure to clean the contact points with lint free paper.

Reinstall the proper flywheel key, flywheel, washer, and torque down the flywheel nut to specification. Reinstall the external coil, but do not tighten down the mounting screws.

ROUND COIL

STEPPED KEY

STEPPED

END

TOWARD

ENGINE

FLYWHEEL

SLEEVE

Timing this system consists of having the proper .0125" (.317 mm) air gap gauge, (Part No. 670297) between the magnets and laminations and torque down the mounting screws to specification. Remove air gap gauge and rotate flywheel to check for any possible striking points. If none are found, the air gap is set correctly and the timing procedure is completed.

.0125” (.317 mm)

SQUARE MODULE

FLYWHEEL SLEEVE

The proper air gap setting between the flywheel magnets and the laminations on both the fixed time and CDI systems is .0125'’. Place .0125'’ gauge, part No. 670297 between the magnets and laminations and torque down mounting screws to specification. Recheck gap setting to make certain there is proper clearance between the magnets and laminations. NOTE: Due to variations between pole shoes, air gap may vary from .005/.020'’ when flywheel is rotated. There is no further timing adjustment on external lamination systems.

SQUARE MODULE

.0125"

OTHER IGNITION SYSTEMS. Ignition systems on engines with a non-adjustable stator, set the points per specification. If the coil is located under the flywheel, no other timing is required.

SET GAP

PER SPECIFICATION

36

If engine has the coil and lamination outside of flywheel, set points per specification and set air gap between flywheel magnets and laminations to .005'’ to .008'’. Air gap gauge, part number 670216 which measures

.0075'’ may be used. Use Loctite "242 Blue" on screws and torque down mounting screws to specification. Remove air gap gauge.

MAGNETS

AIR GAP

DIMENSION

.005

.008

37

OUTBOARD TIMING

OUTBOARD TIMING. (STANDARD IGNITION). Follow Adjust ignition points to proper specification. the step-by-step procedure outlined for timing outboard

engines with Standard ignition magnetos (non-solid state).

Apply a small amount of E.P. Lithium grease to the contact area of the friction screw. Do not turn the screw into the radius of the stator collar.

CONTACT

AREA OF

FRICTION

SCREW

Install the stator with operating handle pointed in the direction of the carburetor. Be sure the throttle post is NOT INSIDE the arc of the throttle actuating cam. Hold the throttle open when installing the stator.

THROTTLE

ACTUATING CAM

THROTTLE POST

CONTROL LEVER

Move the control lever to full retard, then move toward full advance while tightening the friction screw until the lever will not vibrate out of position when the engine is running and yet can be easily rotated when speed is adjusted.

Clean points by sliding lint free paper back and forth between the contacts. Manually open points when removing paper to eliminate paper fiber from remaining between contacts.

Using a dial indicator, set the piston to the proper Before-Top-Dead-Center (BTDC) to the specified dimension.

T.D.C.

B.T.D.C.

Remove leads from point terminal, then reinstall and tighten the nut and washer. Attach a continuity device to the point terminal post and to a good ground on the engine as shown.

LEADS

REMOVED

FRICTION

SCREW

 

POINT

NUT AND WASHER

TERMINAL POST

38

Move the stator counterclockwise, advancing the timing until the continuity reading breaks and reads zero. Tighten the stop bracket to secure the stator.

Loosen the actuating cam locking screws just enough to allow adjustment of the cam. Move the actuating cam to open the throttle completely WITHOUT causing any binding with the throttle post.

LOCKING

SCREWS

GREASE CAM

SURFACE

THROTTLE

STOP

ACTUATING

BRACKET

CAM

 

THROTTLE POST

 

To coordinate the carburetor idle with ignition timing, rotate the crankshaft clockwise, to .003'’ After-Top- Dead-Center (ATDC).

Rotate the control lever toward the idle position until continuity is obtained.

Move the throttle actuating cam until it just touches the throttle post, without moving it.

Tighten the screw slightly, then check the run position and idle position alternately to make sure the actuating cam is adjusted for both positions. Now tighten the screws.

KEEP

CONTINUITY

LEADS ON

TERMINAL POST

AND GROUND

THROTTLE

ACTUATING

CAM

SET CAM SO THAT IT

JUST TOUCHES THE

THROTTLE LEVER POST

MOVE CONTROL LEVER

UNTIL POINTS OPEN

OUTBOARD TIMING. (SOLID STATE). Follow these step-by-step procedures outlined for timing outboard engines with solid state magnetos.

FRICTION

SCREW

Using a dial indicator, set the piston to the specified Before-Top-Dead-Center (BTDC) dimension.

T.D.C.

B.T.D.C.

Install timing tool 670238A on the crankshaft, be careful not to distort the keyway area.

Without disturbing the BTDC piston position, move the control lever counterclockwise until the run trigger aligns with the timing tool (670238A) notch marked #1. Hold this position.

NOTE: Some models do not have the “start” trigger.

CONTROL POS. -2

LEVER

TOOL 670238A

THIS SIDE UP

POS. -1

"RUN" TRIGGER

GROUND SCREW

39

Adjust the stop bracket to prevent the control lever from moving any further counterclockwise. Then tighten the stop bracket screw.

Loosen the actuating cam lock screw enough to allow adjustment of the cam. Position the cam so that it opens the throttle completely, making sure that the cam doesn’t cause binding on the post.

When the correct position is attained, tighten the lock screw on the “high” end to hold the cam in place.

THROTTLE

LOCK SCREWSACTUATING CAM

GREASE CAM

 

SURFACE

 

SCREW

THROTTLE POST

STOP BRACKET

 

CONTROL LEVER

 

Move the control lever to align the “RUN” trigger of the ignition unit with the number 2 position of the timing tool. Hold this position.

TOOL 670238A

THIS SIDE UP

"START"

TRIGGER

"RUN" TRIGGER

POS. -2

Adjust the actuating cam to touch the post without moving it. Tighten the lock screw to hold the cam in place.

GROUND SCREW

THROTTLE

"RUN"

ACTUATING

 

CAM

 

LOCKING

SCREWS

STOP

BRACKET

THROTTLE POST

CONTROL LEVER

Recheck to insure that the high speed point hasn’t changed or that binding will not occur. Readjust from the high speed point to the pickup point as necessary.

When assured that the cam position is correct at the FULL RUN and IDLE positions, torque the lock screw to 10-15 in. lbs.

40

CYLINDERS & INTERNAL COMPONENTS

PISTON & RING SERVICE

Before removing the piston, clean all carbon from the cylinder, making certain that the carbon ridge is removed from the top of the cylinder. This will prevent ring damage when removing the piston.

Push the piston through the top of the cylinder using a wooden dowel on the inside of the piston so that the connecting rod and other parts will not be damaged.

Most models have offset pistons. The pistons on these models have a “V” or "S" stamped on the piston head. When installing piston, this “V” mark must be in a 3 o’clock position when viewing the engine with the exhaust ports down.

"S" OR "V" MARK AT THE 3 O'CLOCK POSITION AND THE EXHAUST PORTS DOWN

Check the piston and cylinder for scoring or other damage.

Check the piston rings for wear by inserting them into the cylinder to about 1/2 inch from the top of the cylinder. Check at various places to make sure that the gap between the ends of the ring do not exceed the dimensions indicated in the Table of Specifications.

Bore wear can be checked by the same method, except, use a new ring to measure the end gap.

FEELER GAUGE

PISTON RING

 

RING

 

CENTERED

 

IN RING

INVERTED PISTON

TRAVEL AREA

 

TO POSITION RING

CHECK RING END GAP

SQUARELY IN CYLINDER

 

Before installing the piston into the bore, put oil on the rings and piston, and stagger the ring end gaps.

STAGGER RING END GAPS

41

CONNECTING ROD SERVICE

Two cycle engines may be equipped with steel or aluminum connecting rods. Aluminum connecting rods use steel liners when needle bearings are utilized.

The connecting rod bolts used are Torx®, size E6. If torx sockets are not locally available, they can be purchased through your Tecumseh parts supplier under part number 670257.

The connecting rod bolts should be tightened alternately and torqued to proper specification.

All connecting rods have match marks on the connecting rod and cap. Make certain these match marks are aligned when assembling.

MATCH MARKS

MATCH MARKS

NEEDLE BEARINGS. Needle bearings may be single or split row.

Split needles are to be installed with the blunt ends together and tapered ends outward.

SINGLE NEEDLE

TAPER

SPLIT NEEDLE

Service needles are supplied with a coating to hold the needles together and make installation easier.

Remove the paper backing on the bearings and wrap uniformly around the crankshaft journal. Pull the connecting rod onto the crankshaft journal, place a few drops of oil onto the needle bearings and install rod cap. Torque bolts to specification.

42

CRANKSHAFT, BEARING AND OIL SEAL SERVICE

Check if crankshaft is bent or otherwise damaged. Make certain keyways are not worn or damaged and flywheel taper is clean and in good condition. If taper or keyways are worn or damaged, replace crankshaft.

Check oil seal contact surfaces on crankshaft for damage or scratches which would damage oil seal or cause leaks.

On engines that are equipped with ball bearings, the crankshaft must be removed with the shroud base.

Before removing shroud base with crankshaft, disassemble rod cap from rod and remove the piston from the bore, then remove four (4) shroud base screws and tap shroud base so base and crankshaft can be removed together.

To remove crankshaft and bearing from shroud base, use following procedure:

Using a propane torch, heat the area of shroud base around the bearing area, until there is enough expansion to remove the crankshaft and bearing.

HEAT AREA

HEAT AREA

 

SHROUD BASE

To remove the bearing from crankshaft, remove retainer ring if so equipped, and use a bearing splitter to pull bearing.

Before installing bearing on crankshaft, clean out the grooves on the crankshaft where bearing locates and put Loctite in the groove. Models with the retainer ring do not require Loctite.

Using a sleeve over the crankshaft, press bearing into position with arbor press. Make certain crankshaft counter weight is supported and bearing is pressed on inner race only.

RETAINER RING (some Models)

BEARING

SUPPORT

COUNTERWEIGHT

To reinstall crankshaft and ball bearing, heat shroud base to expand bearing seat and drop ball bearing into seat of base shroud. Allow to cool.

On outboards only, install shroud base onto cylinder but before tightening screws, rotate shroud base fully clockwise. Tighten screws.

If a ball bearing engine appears to be tight, or if the flywheel was removed with the use of a knock-off tool, the ball bearing may be dislodged from shroud base, forcing the crankshaft lower thrust face against the cylinder thrust face, To correct this condition, rap sharply on the P.T.O. end of the crankshaft with rawhide mallet to provide the clearance between the crankshaft and cylinder thrust face.

BALL BEARING

MUST HAVE

CLEARANCE

NEEDLE BEARINGS. Caged needle bearings can be removed and replaced by pressing them in and out of cylinder using an arbor press.

NOTE: Always press against the lettered side of the bearing.

If the needles fall out of the cage, they can be reinstalled using grease to hold them in position.

OIL SEALS. It is important on 2 cycle engines that oil seals are in good condition. A leaky seal will cause hard starting, erratic running, and possible damage to internal components due to a lean fuel-oil mixture caused by extra air getting into the crankcase.

Engines could be equipped with either one piece oil seals or three pieces consisting of a seal, retainer and retainer ring; they are not interchangeable.

ONE PIECE SEALS. An oil seal remover tool can be used for seal removal in some engines. In some cases it may be necessary to disassemble engine to remove the oil seals.

Seal driver-protectors are available for most one piece oil seals. Select the proper tool from the tool list in Chapter 8. Place the oil seal over the driver protector, place over crankshaft, and drive into position using universal driver No. 670272.

DRIVER (No. 670272)

OIL SEAL

DRIVER-PROTECTOR

43

THREE PIECE SEALS. To remove seals, use a sharp object such as an ice pick to pry out the retainer spring, then remove the retainer and seal. In some cases it may be necessary to remove the crankshaft to remove the oil seals.

RETAINER SPRING

RETAINER

SEAL

RING

RETAINER

SEAL

OUTBOARD SEAL SERVICE. Oil seals on the power- take-off end of the crankshaft are installed in an inverted (upside down) position to keep water out of engine.

44

CYLINDERS, REEDS & COMPRESSION RELEASE

CYLINDER & HEAD SERVICE. Check cylinder for bore damage or scoring. Check for broken or cracked fins, warped head or head mounting surface. If warped extensively, (more than .005"/.127 mm) replace. Always replace head gasket and torque to proper specification.

GASKETS. Replace all gaskets in reassembly and make sure all sealing surfaces will not leak. A leaking gasket will cause erratic running, hard starting and could damage internal components by causing an imbalance of fuel-oil air mixture.

REED VALVES. Make sure reeds and sealing surfaces are free of dirt and foreign matter. Check reeds for seal against sealing surface of the adapter. Reeds should not bend away from sealing surface more than

.010'’ (.254 mm).

If the reeds are serviceable, the smooth side of the reed must locate against the sealing surface. Service reeds have “smudge” marks on smooth side. If these marks are gone, feel for a rough edge and assemble away from sealing surface.

AUTOMATIC COMPRESSION RELEASE (DOUBLE REED TYPE).

Cranking compression pressures bleed past reeds and into muffler. Once the engine is started, a high pressure build-up between the reeds forces the reeds against their seats stopping compression bleed off and allowing engine to run at full compression.

CYLINDER REED

Replace both reeds If either is defective. When installing reeds be sure the colored side of the reed faces its seating surface. If in doubt, feel for a rough edge on the reed. The rough edge must be installed away from the seating surface. Assemble reed stop and hold down and tighten self-tapping screws.

Poor running or lack of power may be caused by a leaking reed or cover gasket.

AUTOMATIC COMPRESSION RELEASE (SINGLE REED TYPE).

Cranking compression pressures bleed past reed valve, through a port, into the piston pin and out the exhaust port.

REED

PISTON

OPEN

 

Ô

 

 

 

 

Ô Ô

Ô

Ô

EXHAUST

SINGLE

 

 

PORT

 

 

 

REED

 

 

 

 

Ô Ô

Ô

 

Ô

 

 

 

REED

 

 

PISTON

OPEN

 

 

 

 

TYPE II

 

PIN

 

 

 

 

As the engine starts and compression increases, the reed will be forced against the bottom port, sealing it and the engine will run under full compression.

REED

 

OPEN

PISTON

 

Ô

 

 

SINGLE

Ô Ô

Ô

Ô

 

 

 

REED

 

 

EXHAUST

 

 

 

 

 

 

PORT

REED

PISTON

CLOSED

PIN

 

TYPE II

Install the reed cover (single reed type) with the small hole towards the spark plug.

COVER REED

TYPE I

45

The piston used in the single reed compression release system has a cutout at the piston pin hole. The piston must be installed with the cut-out located on the side facing the compression release.

CYLINDER EXHAUST PORTS. The muffler and cylinder exhaust ports should be cleaned after each seventy- five (75) to one hundred (100) hours of operation.

It is recommended that the cylinder head be removed and carbon cleaned from the ports, cylinder head and top of piston.

CAUTION: Do Not Scratch Metal Surfaces.

With the cylinder head removed, remove any carbon deposits from the cylinder wall, head, and the top of the piston. Using a pointed 3/8'’ wooden dowel or similar tool, remove the carbon from the exhaust ports. Being sure to remove all loose carbon particles from the engine.

NOTE: When cleaning the exhaust ports, check and clean the compression release passage.

46

TROUBLESHOOTING

2 CYCLE ENGINE TROUBLESHOOTING CHART

Cause

Remedy and Reference

ENGINE FAILS TO START OR STARTS WITH DIFFICULTY

No fuel in tank

Fill tank with clean, fresh fuel with correct oil ratio.

Fuel shut-off valve closed

Open valve.

Obstructed fuel line

Clean fuel screen and line. If necessary, remove

 

and clean carburetor.

Tank cap vent obstructed

Open vent in fuel tank cap or replace cap.

Water in fuel

Drain tank. Clean carburetor and fuel lines. Dry

 

spark plug points. Fill tank with clean, fresh fuel.

Engine overchoked

Close fuel shut-off and pull starter until engine starts.

 

Reopen fuel shutoff for normal fuel flow immediately

 

after engine starts.

Improper carburetor adjustment

Adjust carburetor.

Loose or defective magneto wiring

Check magneto wiring for shorts or grounds; repair

 

if necessary.

Sheared or incorrect flywheel key or adapter sleeve

Replace with correct key or adapter sleeve.

Faulty Magneto

Check timing, point gap, and if necessary, overhaul

 

magneto.

Spark plug fouled

Clean and regap spark plug.

Crankcase seals and/or gaskets leaking

Replace seals and/or gaskets.

Spark plug porcelain cracked

Replace spark plug.

Poor Compression

Overhaul engine.

Exhaust ports plugged

Clean exhaust ports

 

 

ENGINE KNOCKS

 

Carbon in combustion chamber

Loose or worn connecting rod

Loose flywheel

Worn cylinder

Improper magneto timing

Remove cylinder head or cylinder and clean carbon from head and piston.

Replace connecting rod.

Check flywheel key and keyway; replace parts if necessary. Tighten flywheel nut to proper torque.

Replace cylinder.

Time magneto.

47

2 CYCLE ENGINE TROUBLESHOOTING CHART (Cont.)

Cause

Remedy

 

 

ENGINE MISSES UNDER LOAD

 

 

 

Spark plug fouled

Clean and regap spark plug.

Spark plug porcelain cracked

Replace spark plug.

Improper spark plug gap

Regap spark plug.

Pitted magneto breaker points

Clean and dress breaker points. Replace badly

 

pitted breaker points.

Magneto breaker arm sluggish

Clean and lubricate breaker point arm.

Faulty condenser

Check condenser on a tester; replace if defective

 

(see test instrument instructions and specifications).

Improper carburetor adjustment

Adjust carburetor.

Reed fouled or sluggish

Clean or replace reed.

Crankcase seal leak

Replace worn crankcase seals.

 

 

ENGINE LACKS POWER

 

 

 

Choke partially closed

Open choke.

Blown head gasket

Replace head gasket.

Improper carburetor adjustment

Adjust carburetor.

Improper or partially sheared flywheel key or

Replace with new correct key or sleeve.

adapter sleeve.

 

Magneto improperly timed

Time magneto.

Worn piston or rings

Replace piston or rings.

Air cleaner clogged

Clean air cleaner.

Reed fouled or sluggish

Clean or replace reed.

Improper amount of oil in fuel mixture

Drain tank; fill with correct mixture (See engine

 

decal).

Carburetor improperly adjusted

Adjust carburetor.

Crankcase seals leaking

Replace worn crankcase seals

 

 

ENGINE OVERHEATS

 

 

 

Engine improperly timed

Time engine.

Improper or partially sheared flywheel key or

Replace with new correct key or sleeve.

adapter sleeve.

 

Air flow obstructed

Remove any obstructions from air passages in

 

shrouds.

Cooling fins clogged

Clean cooling fins.

 

 

48

2 CYCLE ENGINE TROUBLESHOOTING CHART (Cont.)

Cause

Remedy

 

 

ENGINE OVERHEATS (continued)

 

 

 

Excessive load on engine

Check operation of associated equipment. Reduce

 

excessive load.

Carbon in combustion chamber

Remove cylinder head or cylinder and clean carbon

 

from head and piston.

Improper amount of oil in fuel mixture

Drain tank; fill with correct mixture.

 

 

ENGINE SURGES OR RUNS UNEVENLY

 

 

 

Fuel tank cap vent hole clogged

Open vent hole.

Crankcase air leak

Inspect and replace gasket or seal.

Governor parts sticking or binding

Clean, and if necessary repair governor parts.

Carburetor throttle linkage or throttle shaft and/or

Clean, lubricate, or adjust linkage and deburr throttle

butterfly binding or sticking

shaft or butterfly.

 

 

ENGINE VIBRATES EXCESSIVELY

 

 

 

Engine not securely mounted

Tighten loose mounting bolts (See equipment

 

instructions).

Bent crankshaft

Replace crankshaft.

Driven equipment out of balance

Recheck driven equipment.

Piston installed incorrectly. Engines with wrist

Install piston correctly.

pin offset.

 

 

 

49

SPECIFICATIONS

ENGINE TYPE NUMBER AND LETTER REFERENCE

Tecumseh has used two different methods of identifying 2 cycle engines.

The first method was used until the mid 1980's using the base model number with a type number. The type number was used to identify variations for the OEM's specific needs.

The second method was put in place to standardize 2 cycle and 4 cycle engine identification. The type number has now become the specification number, which is preceded by the engine model. Example: AV520

Tecumseh type numbers are stamped into the blower housing, or are located on a nameplate or tag on the engine.

Model and Specification numbers are either stamped into the blower housing, or located on a decal on the side of the blower housing.

 

 

Column

 

 

Column

 

 

Column

TYPE NO.

No.

 

TYPE NO.

No.

 

TYPE NO.

No.

 

Vertical Crankshaft Engines

 

Horizontal Crankshaft Engines

 

Horizontal Crankshaft Engines

 

 

 

 

 

 

 

 

 

 

638 thru 638-100

6

 

 

1401J

27

 

1519 thru 1521

1

 

639 thru 639-13A

13

 

 

1402 and 1402B

7

 

1522

12

 

640-02 thru 640-06B 21

 

 

 

1425

7

 

1523

1

 

640-07 thru 640-21-A

22

 

 

1430A

7

 

1524

2

 

640-23

 

36

 

 

1432, A

7

 

1525A

16

 

641 thru 641-14

11

 

 

1440, A, B, C, D

1

 

1527

3

 

642-01,A

9A

 

 

 

1442, A, B,

7

 

1528,A,B

1

 

642-02, A thru G

9A

 

1444, A

7

 

1529, A, B

3

 

642-02E, F

9B

 

1448 thru 1450

16

 

1530, A, B

1

 

642-03, A, B

9A

 

1450A, A, B, C, D, E

16

 

1531

3

 

642-04, A, B, C

9A

 

1450F

17

 

1534A

17

 

642-05, A, B

9A

 

1454, A

1

 

1535B

3

 

642-06, A

 

9A

 

1459

7

 

1536

12

 

642-07, A, B

9A

 

1460, A, B ,C, D, E, F

1

 

1537

1

 

642-07C

 

9B

 

1462

1

 

1538 thru 1541A

12

 

642-08

 

9B

 

1464, A, B

12

 

1542

5

 

642-08A, B, C

9A

 

1465

1

 

1543 thru 1546

1

 

642-09 thru 642-14

9A

 

1466, A

16

 

1547

3

 

642-13 thru 14C

9B

 

1471, A, B

5

 

1549

3

 

642-15 thru 642-23

9B

 

1472, A, B, C

12

 

1550A

15

 

642-24 thru 642-33

9C

 

1473, A, B

1

 

1551

16

 

642-35

 

34

 

 

1474

12

 

1552

20

 

643-01, A, 03, A

10A

 

1475 thru 1476

1

 

1553

16

 

643-03B, C

10B

 

1479

7

 

1554,A

3

 

643-04, 05A

10A

 

1482, A

16

 

1555 and 1556

16

 

643-05B

 

10B

 

1483

16

 

1557 thru 1560

15

 

643-13,14

 

10A

 

1484, A, B, C, D

3

 

1561

19

 

643-14A, B, C

10B

 

1485

7

 

1562 thru 1571

23

 

643-15

 

10A

 

1486

4

 

1572

2

 

643-15A thru 643-32

10B

 

1488, A, B, C, D

1

 

1573

3

 

643-32A

 

32

 

 

1489 thru 1490B

3

 

1574 thru 1577

23

 

643-33

 

33

 

 

1491

12

 

1575

24

 

643-34

 

33

 

 

1493, A

7

 

1578

25

 

643-35,A,B

37

 

 

1494 and 1495A

2

 

1581 thru 1582A

23

 

650

 

14

 

 

1496

7

 

1583 thru 1599A

26

 

653-01 thru 653-05

31

 

 

1497

1

 

1600 thru 1617

28

 

653-07 thru 653-10

38

 

 

1498

5

 

1618 thru 1619

43

 

660-11 thru 660-38

18

 

 

1499

16

 

1620

30

 

660-39,A

 

39

 

 

1500

5

 

1622 thru 1623A

42

 

660-40

 

40

 

 

1501,A, B, C, D, E,F,G

1

 

1624 thru 1642

35

 

661-01 thru 661-29

29

 

 

1503, A, B, C, D

12

 

 

 

 

661-30 thru 661-45

41

 

 

1506

16

 

 

 

 

662-02

 

42

 

 

1506B

17

 

 

 

 

 

 

 

 

 

 

 

662-623A

42

 

 

 

1507

16

 

MODEL

PAGE NO.

670-01 thru 670-109

8

 

 

1508

7

 

 

 

 

 

 

 

 

 

 

 

 

1509

3

 

AV520

61

 

 

 

 

 

 

1510

12

 

AV600

61

 

Horizontal Crankshaft Engines

 

 

 

 

1511

3

 

AH600

61

 

1398 thru 1399

11

 

 

1512, A

2

 

HSK600

61

 

 

 

1513

12

 

TVS600

61

 

1400

 

11

 

 

 

 

 

 

 

1515 thru 1516C

3

 

 

 

 

1401 thru 1401F

16

 

 

 

 

 

 

 

 

1517

5

 

 

 

 

1401G, H

 

17

 

 

 

 

 

 

 

 

 

1518

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

50

SEARS CRAFTSMAN CROSS REFERENCE

Craftsman

Vertical Crankshaft Engines

Craftsman No. 200.183112 200.183122 200.193132 200.193142 200.193152 200.193162 200.203112 200.203172 200.203182 200.203192 200.213112 200.213122 200.213132 200.223112 200.233112 200.243112 200.283012 200.2131128 200.2132228

Column No. 6 6 6 6 7 7 8 8 8 8 8 8 8

41

41

8

8

31

29

Craftsman

Horizontal Crankshaft Engines

Craftsman No. 200.503111 200.583111 200.593121 200.602112 200.613111 200.633111 200.643121 200.672102 200.682102 200.692112 200.692122 200.692132 200.701001 200.711001 200.731001 200.731011 143.943071 143.953071 143.973071 143.973091 143.983071 143.993071

Column No. 16 16 16 35 16 35 35 26 26 26 26 26

AH600-1665N HSK600-1665P HSK600-1686R HSK600-1687R HSK600-1687S HSK600-1700S HSK600-1705S HSK600-1700S HSK600-1708T HSK600-1712T

51

TABLE OF SPECIFICATIONS

Reference Column

 

1

 

2

 

3

 

 

4

 

5

 

U.S.

 

Metric

U.S.

Metric

U.S.

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

mm

 

mm

 

mm

 

 

mm

 

 

mm

Bore

2.093

 

53.162

2.093

53.162

2.093

53.162

2.093

 

53.162

2.093

 

53.162

 

2.094

 

53.188

2.094

53.188

2.094

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

1.250

 

31.75

1.410

35.814

1.410

35.814

1.410

 

35.814

1.410

 

35.814

Cu. In. Displacement

4.40

 

72.1

4.80

78.7

4.80

78.7

4.80

 

78.7

4.80

 

78.7

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

.017

 

.432

.017

.432

.017

.432

.017

 

.432

.017

 

.432

Timing

.122

 

3.098

.100

2.54

.135

3.429

.100

 

2.54

.135

 

3.429

B.T.D.C.

 

 

 

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

.030

 

.762

.030

.762

.030

.762

.030

 

.762

.030

 

.762

Piston Ring

.007

 

.178

.007

.178

.006

.15

.006

 

.15

.006

 

.15

End Gap

.017

 

.432

.017

.432

.011

.28

.014

 

.35

.011

 

.28

Piston

2.0870

 

53.01

2.0870

53.01

2.0875

53.023

2.0875

 

53.023

2.0875

 

53.023

Diameter

2.0880

 

53.035

2.0880

53.035

2.0885

53.048

2.0885

 

53.048

2.0885

 

53.048

(Top)

.0655

 

1.664

.0655

1.664

.0655

1.664

.0975

 

1.664

.0655

 

1.664

Piston Ring

.0665

 

1.689

.0665

1.689

.0665

1.689

.0985

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

&nnbsp;

1.638

.0645

1.638

.0645

1.638

.0955

 

1.638

.0645

 

1.638

 

 

 

 

(Bot.)

.0655

 

1.664

.0655

1.664

.0655

1.664

.0965

 

1.664

.0655

 

1.664

Piston Ring

.0615

 

1.562

.0615

1.562

.0615

1.562

.0925

 

2.35

.0615

 

1.562

Width

.0625

 

1.587

.0625

1.587

.0625

1.587

.0935

 

2.375

.0625

 

1.587

Piston Pin

.4997

 

12.692

.4997

12.692

.4997

12.692

.3750

 

9.525

.4997

 

12.693

Diameter

.4999

 

12.697

.4999

12.697

.4999

12.697

.3751

 

9.528

.4999

 

12.697

Crank Pin Journal

.5611

 

14.252

.5614

14.260

.5614

14.260

.6857

 

17.417

.5611

 

14.252

Diameter

.5618

 

14.270

.5621

14.277

.5621

14.277

.6865

 

17.437

.5618

 

14.270

Crankshaft

.6691

 

16.995

.6691

16.995

.6691

16.995

.6691

 

16.995

.6691

 

16.995

P.T.O. Side

.6695

 

17.005

.6695

17.005

.6695

17.005

.6695

 

17.005

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.6691

 

16.995

.6691

16.995

.6691

16.995

.6691

 

16.995

.6691

 

16.995

Magneto Side

.6695

 

17.005

.6695

17.005

.6695

17.005

.6695

 

17.005

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

 

None

None

None

None

None

None

 

None

None

 

None

End Play

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

52

TABLE OF SPECIFICATIONS

Reference Column

 

6

7

 

8

 

 

9A

 

9B

 

 

 

 

 

 

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

 

mm

 

 

mm

 

mm

 

 

mm

 

 

mm

Bore

 

2.093

 

53.162

2.093

 

53.162

2.093

53.162

2.093

 

53.162

2.093

 

53.162

 

 

2.094

 

53.188

2.094

 

53.188

2.094

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

 

1.500

 

38.1

1.500

 

38.1

1.500

38.1

1.500

 

38.1

1.500

 

38.1

Cu. In. Displacement

5.20

 

85.2

5.20

 

85.2

5.20

85.2

5.20

 

85.2

5.20

 

85.2

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

 

.018

 

.457

.017

 

.432

.020

.508

.018

 

.457

.020

 

.508

Timing

 

.100

 

2.54

.185

 

4.699

.070

1.778

.100

 

2.54

.085

 

2.159

B.T.D.C.

 

 

 

 

 

 

 

See Note 1

 

See Note 2

 

 

 

 

Spark Plug Gap

.030

 

.762

.030

 

.762

.030

.762

.030

 

.762

.030

 

.762

Piston Ring

 

.006

 

.153

.007

 

.178

.006

.153

.007

 

.178

.006

 

.153

End Gap

 

.014

 

.356

.017

 

.432

.016

.406

.017

 

.432

.016

 

.406

Piston

 

2.0870

 

53.01

2.0870

 

53.01

2.0870

53.01

2.0870

 

53.01

2.0870

 

53.01

Diameter

 

2.0880

 

53.035

2.0880

 

53.035

2.0880

53.035

2.0880

 

53.035

2.0880

 

53.035

Piston Ring

(Top)

.0975

 

1.664

.0655

 

1.664

.0655

1.664

.0655

 

1.664

.0655

 

1.664

Groove Width

 

.0985

 

1.689

.0665

 

1.689

.0665

1.689

.0665

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0955

 

1.638

.0645

 

1.638

.0645

1.638

.0645

 

1.638

.0645

 

1.638

 

(Bot.)

.0965

 

1.664

.0655

 

1.664

.0655

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

 

.0925

 

2.35

.0615

 

1.562

.0615

1.562

.0615

 

1.562

.0615

 

1.562

Width

 

.0935

 

2.375

.0625

 

1.587

.0625

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

 

.3750

 

9.525

.4997

 

12.692

.4997

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

 

.3751

 

9.528

.4999

 

12.697

.4999

12.697

.4999

 

12.697

.4999

 

12.697

Crank Pin Journal

.6857

 

17.417

.5611

 

14.252

.8442

21.443

.6857

 

17.417

.8442

 

21.443

Diameter

 

.6865

 

17.437

.5618

 

14.270

.8450

21.463

.6865

 

17.437

.8450

 

21.463

Crankshaft

 

.8745

 

22.212

.6690

 

16.993

.9998

25.349

.8745

 

22.212

.9998

 

25.349

P.T.O. Side

 

.8750

 

22.225

.6694

 

17.003

1.0003

25.408

.8750

 

22.225

1.0003

 

25.408

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

 

 

 

 

Ball Bearing

 

 

 

 

 

 

 

 

 

 

Magneto Side

 

.7495

 

19.037

.6690

 

16.993

.6691

16.995

.7495

 

19.037

.7498

 

19.045

Main Brg. Dia.

 

.7500

 

19.05

.6694

 

17.003

.6695

17.005

.7500

 

19.05

.7503

 

19.058

 

 

 

 

 

See Note A

 

 

 

 

 

 

 

 

 

 

Crankshaft

 

.003

 

.076

None

 

None

None

None

.003

 

.076

.003

 

.076

End Play

 

.016

 

.406

 

 

 

 

 

.016

 

.406

.016

 

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE 1: 642-08, 14A, 14B B.T.D.C. = .110

642-16D, 19A, 20A, 21, 22 B.T.D.C. = .078

NOTE 2: 642-24, 26, 29 B.T.D.C. = .087

NOTE A: Needle Bearing ..74987503

53

TABLE OF SPECIFICATIONS

Reference Column

9C

 

10A

 

10B

 

 

11

 

12

 

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

 

mm

 

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

 

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

 

 

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

 

1.500

 

38.1

1.750

 

44.45

1.750

 

44.45

1.750

 

44.45

1.410

 

35.814

Cu.In. Displacement

5.20

 

85.2

6.00

 

98.3

6.00

 

98.3

6.00

 

98.3

4.80

 

78.7

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

 

.020

 

.508

.018

 

.457

.020

 

.508

.018

 

.457

.017

 

.432

 

 

 

 

 

See Note 4

 

 

 

 

 

 

 

 

 

 

 

Timing

 

.078

 

1.98

.090

 

2.286

.087

 

2.21

.100

 

2.54

.135

 

3.429

B.T.D.C.

 

See Note 2

 

 

See Note 3

 

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston RIng

 

.006

 

.152

.007

 

.178

.006

 

.152

.006

 

.152

.007

 

.178

End Gap

 

.016

 

.406

.017

 

.432

.016

 

.406

.014

 

.356

.017

 

.432

Piston

 

2.0870

 

53.01

2.0870

 

53.01

2.0870

 

53.01

2.0873

 

53.017

2.0870

 

53.01

Diameter

 

2.0880

 

53.035

2.0880

 

53.035

2.0880

 

53.035

2.0883

 

53.043

2.0880

 

53.035

(Top)

 

.0655

 

1.664

.0655

 

1.664

.0665

 

1.689

.0655

 

1.664

.0655

 

1.664

Piston Ring

 

.0665

 

1.689

.0665

 

1.689

.0975

 

2.477

.0985

 

2.413

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0955

 

2.426

.0645

 

1.638

 

 

 

 

 

 

 

(Bot.)

 

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0965

 

2.451

.0655

 

1.664

Piston Ring

 

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0625

 

1.587

Width

 

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0935

 

2.375

.0925

 

2.349

Piston Pin

 

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

 

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

Crank Pin Journal

.8442

 

21.443

.6857

 

12.417

.8442

 

21.443

.6857

 

17.417

.5614

 

14.26

Diameter

 

.8450

 

21.463

.6865

 

17.437

.8450

 

21.463

.6865

 

17.437

.5621

 

14.277

Crankshaft

 

.9998

 

25.395

.8745

 

22.212

.9998

 

25.395

.8745

 

22.212

.6691

 

16.995

P.T.O. Side

 

1.0003

 

25.408

.8750

 

22.225

1.0003

 

25.408

.8750

 

22.225

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

 

.6691

 

16.995

.7495

 

19.037

.7498

 

19.045

.7495

 

10.037

.6691

 

16.995

Magneto Side

.6695

 

17.005

.7500

 

19.05

.7503

 

19.058

.7500

 

19.05

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

 

None

 

None

.003

 

.076

.003

 

.076

.003

 

.076

None

 

None

End Play

 

 

 

 

.016

 

.406

.016

 

.406

.016

 

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE 2:

642-24, 26, 29 B.T.D.C. = .087

 

 

 

 

 

 

 

 

 

 

 

 

NOTE 3:

643-13 B.T.D.C. = .095

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE 4:

643-93A, 05A, 13, 14 = .020

 

 

 

 

 

 

 

 

 

 

 

 

54

TABLE OF SPECIFICATIONS

Reference Column

13

 

14

 

 

15

 

16

 

17

 

U.S.

Metric

U.S.

Metric

U.S.

Metric

U.S.

Metric

U.S.

Metric

 

 

mm

 

mm

 

mm

 

mm

 

mm

Bore

2.375

60.33

2.093

53.162

2.4375

61.913

2.093

53.162

2.093

53.162

 

2.376

60.35

2.094

53.188

2.4385

61.938

2.094

53.188

2.094

53.188

Stroke

1.680

42.672

1.500

38.1

1.750

44.45

1.500

38.1

1.500

38.1

Cu. In. Displacement

7.50

122.9

5.20

85.2

8.17

133.9

5.20

85.2

5.20

85.2

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

Point Gap

.020

.508

.018

.457

.018

.457

.017

.432

.017

.432

Timing

.095

2.413

.100

2.54

.100

2.54

.110

2.794

.110

2.794

B.T.D.C.

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

.030

.762

.030

.762

.030

.762

.030

.762

.030

.762

Piston Ring

.005

.127

.006

.152

.007

.178

.006

.152

.006

.152

End Gap

.013

.330

.014

.356

.017

.432

.016

.406

.016

.406

Piston

2.3685

60.16

2.0870

53.01

2.4302

61.727

2.0875

53.023

2.0880

53.035

Diameter

2.3695

60.185

2.0880

53.035

2.4312

61.753

2.0885

53.048

2.0890

53.061

(Top)

.0655

1.664

.0975

1.664

.0655

1.664

.0645

1.638

.0645

1.638

Piston Ring

.0665

1.664

.0985

1.689

.0665

1.664

.0655

1.664

.0655

1.664

 

 

 

 

 

 

 

 

 

 

Groove Width

.0645

1.638

.0955

2.426

.0645

1.638

.0645

1.638

.0645

1.638

 

(Bot.)

.0655

1.664

.0965

2.451

.0655

1.664

.0655

1.664

.0655

1.664

Piston Ring

.0615

1.562

.0615

1.562

.0625

1.587

.0615

1.562

.0615

1.562

Width

.0625

1.587

.0935

2.375

.0925

2.35

.0625

1.587

.0625

1.587

Piston Pin

.4997

12.692

.3750

9.525

.4997

12.692

.3750

9.525

.4997

12.692

Diameter

.4999

12.697

.3751

9.528

.4999

12.698

.3751

9.528

.4999

12.697

Crank Pin Journal

.6259

15.898

.6957

17.671

.6259

15.898

.6857

17.417

.6857

17.417

Diameter

.6266

15.916

.6865

17.427

.6266

15.916

.6868

17.445

.6865

17.445

Crankshaft

.8650

21.971

.8745

22.12

.6691

16.995

.6691

16.995

.9998

25.349

P.T.O. Side

.8850

22.479

.8750

22.225

.6695

17.001

.6695

17.001

1.0003

25.408

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

Crankshaft

.7495

19.037

.7495

19.037

.7495

19.037

.7495

19.037

.7495

19.037

Magneto Side

.7503

19.058

.7500

19.058

.7500

19.058

.7500

19.058

.7500

19.058

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

None

.003

.076

None

None

None

None

None

None

End Play

 

 

.016

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

55

TABLE OF SPECIFICATIONS

Reference Column

 

 

18

 

19

20

 

 

21

 

22

 

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

 

mm

 

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

 

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.4375

 

61.913

2.437

 

61.900

 

 

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.4385

 

61.938

2.438

 

61.925

Stroke

 

1.750

 

44.45

1.410

 

35.814

1.250

 

31.75

1.750

 

44.45

1.750

 

44.45

Cu. In. Displacement

 

6.02

 

98.7

4.80

 

78.7

4.40

 

72.1

8.17

 

133.9

8.17

 

133.9

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

 

.020

 

.508

.017

 

.432

.017

 

.432

.020

 

.508

.020

 

.508

Timing

 

.070

 

1.778

.100

 

2.54

.122

 

3.099

.118

 

2.997

.115

 

2.921

B.T.D.C.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

 

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston Ring

 

.006

 

.152

.007

 

.178

.007

 

.178

.007

 

.178

.007

 

.178

End Gap

 

.016

 

.406

.017

 

.432

.017

 

.432

.017

 

.432

.017

 

.432

Piston

 

2.0870

 

53.01

2.0870

 

53.01

2.0870

 

53.01

2.4302

 

61.727

2.4302

 

61.727

Diameter

 

2.0880

 

53.035

2.0880

 

53.035

2.0880

 

53.035

2.4312

 

61.753

2.4312

 

61.753

(Top)

 

.0645

 

1.638

.0645

 

1.638

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

 

.0655

 

1.664

.0655

 

1.664

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

 

 

 

 

 

 

 

(Bot.)

 

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

 

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

Width

 

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

 

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

 

.4999

 

12.675

.4999

 

12.675

.4999

 

12.675

.4999

 

12.675

.4999

 

12.675

Crank Pin Journal

 

.8442

 

21.443

.5614

 

14.26

.5611

 

14.252

.6259

 

15.898

.6919

 

17.574

Diameter

 

.8450

 

21.463

.5621

 

14.277

.5618

 

14.270

.6266

 

15.916

.6927

 

17.595

Crankshaft

 

.6691

 

16.995

.6691

 

16.995

.6691

 

16.995

.6691

 

16.995

.6691

 

16.995

P.T.O. Side

 

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

Ball Bearing

 

 

 

 

 

 

 

 

 

 

 

 

 

Magneto Side

 

.9998

 

25.395

.6691

 

16.995

.6691

 

16.995

.8745

 

22.212

.8748

 

22.223

Main Brg. Dia.

 

1.0003

 

25.408

.6695

 

17.005

.6695

 

17.005

.8750

 

22.225

.8753

 

22.233

 

See Note A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

 

None

 

None

None

 

None

None

 

None

None

 

None

None

 

None

End Play

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NOTE A: Needle Bearing

.7498

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.7503

 

 

 

 

 

 

 

 

 

 

 

 

 

 

* Does not apply to units with Solid State Ignition.

56

TABLE OF SPECIFICATIONS

Reference Column

 

23

 

24

 

25

 

26

 

27

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

mm

 

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

 

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

.1500

 

38.1

1.410

 

35.814

.1410

 

35.814

1.500

 

38.1

1.500

 

38.1

Cu. In. Displacement

5.20

 

85.2

4.80

 

78.7

4.80

 

78.7

5.20

 

85.2

5.20

 

85.2

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

.017

 

.432

.017

 

.432

.020

 

.508

.020

 

.508

.017

 

.432

Timing

.110

 

2.794

.135

 

3.429

Fixed

 

Fixed

.062

 

1.575

.100

 

2.54

B.T.D.C.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston Ring

.006

 

.152

.007

 

.178

.007

 

.178

.006

 

.152

.006

 

.152

End Gap

.016

 

.406

.017

 

.432

.017

 

.432

.016

 

.406

.016

 

.406

Piston

2.0870

 

53.01

2.0870

 

53.01

2.0870

 

53.01

2.0870

 

53.01

2.0875

 

53.01

Diameter

2.0880

 

53.035

2.0880

 

53.035

2.0880

 

53.035

2.0880

 

53.035

2.0885

 

53.035

(Top)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

 

 

 

 

 

 

(Bot.)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

Width

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

Crank Pin Journal

.6919

 

17.574

.5614

 

14.26

.5614

 

14.26

.6919

 

17.574

.6922

 

17.582

Diameter

.6927

 

17.595

.5621

 

14.277

.5621

 

14.277

.6927

 

17.595

.6927

 

17.595

Crankshaft

.6691

 

16.995

.6691

 

16.995

.6691

 

16.995

.7498

 

19.045

.6691

 

16.995

P.T.O. Side

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.7503

 

19.058

.6695

 

17.005

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.7498

 

19.045

.6691

 

17.551

.6691

 

17.551

.6691

 

17.551

.7498

 

19.045

Magneto Side

.7503

 

19.058

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.7503

 

19.058

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

 

None

None

 

None

None

 

None

None

 

None

.003

 

.076

End Play

 

 

 

 

 

 

 

 

 

 

 

 

.016

 

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

57

TABLE OF SPECIFICATIONS

Reference Column

28

 

29

 

30

 

 

31

 

32

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

mm

 

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

 

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

1.500

 

38.1

1.746

 

44.348

1.746

 

44.348

1.500

 

38.1

1.746

 

44.348

Cu. In. Displacement

5.20

 

85.2

6.0

 

98.3

6.0

 

98.3

5.20

 

85.2

6.0

 

98.3

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

.020

 

.508

.020*

 

.508

.020

 

.508

.020

 

.508

.020

 

.508

Timing

Ext.

 

Ext.

Ext.

 

Ext.

.052

 

1.321

Ext.

 

Ext.

.088

 

2.235

B.T.D.C.

Ignition

 

Ignition

Ignition

 

Ignition

 

 

 

Igniton

 

Ignition

 

 

 

Spark Plug Gap

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston Ring

.006

 

.152

.007

 

.178

.006

 

.152

.006

 

.152

.006

 

.152

End Gap

.016

 

.152

.017

 

.432

.016

 

.152

.016

 

.152

.016

 

.152

Piston

2.0875

 

53.023

2.0865

 

52.997

2.0875

 

53.023

2.0865

 

52.997

2.0865

 

52.997

Diameter

2.0885

 

53.048

2.0875

 

53.023

2.0885

 

53.048

2.0875

 

53.028

2.0875

 

53.023

(Top)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

 

 

 

 

 

 

(Bot.)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0615

 

1.652

.0615

 

1.652

.0615

 

1.652

.0615

 

1.652

.0615

 

1.652

Width

.06251

 

.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

Crank Pin Journal

.6922

 

17.582

.8113

 

20.607

.8113

 

20.607

.8113

 

20.607

.8445

 

21.450

Diameter

.6927

 

17.595

.8118

 

20.620

.8118

 

20.620

.8118

 

20.620

.8450

 

21.463

Crankshaft

.7498

 

19.045

.9998

 

25.395

.7498

 

19.045

.9998

 

25.395

.9998

 

25.395

P.T.O. Side

.7503

 

19.058

1.0003

 

25.408

.7503

 

19.058

1.0003

 

25.408

1.0003

 

25.408

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.7498

 

17.005

.6695

 

17.005

Magneto Side

.6699

 

17.015

.6699

 

17.015

.6699

 

17.015

.7503

 

17.015

.6699

 

17.015

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

 

None

None

 

None

None

 

None

None

 

None

.003

 

.076

End Play

 

 

 

 

 

 

 

 

 

 

 

 

.016

 

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*Does not apply to units with Solid State Ignition.

58

TABLE OF SPECIFICATIONS

Reference Column

 

33

 

34

 

35

 

36

37

 

 

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

mm

 

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

2.437

 

61.90

2.093

 

53.162

 

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

2.438

 

66.925

2.094

 

53.188

Stroke

1.746

 

44.348

1.746

 

44.348

1.500

 

38.1

1.746

 

44.348

1.750

 

44.45

Cu. In. Displacement

6.0

 

98.3

6.0

 

98.3

5.20

 

85.2

6.0

 

98.3

6.0

 

98.3

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

.020

 

.508

.020

 

.508

*.020

 

.508

.020

 

.508

.020

 

.508

Timing

.073

 

1.854

.078

 

1.854

Ext.

 

Ext.

.112

 

2.845

.088

 

2.235

B.T.D.C.

 

 

 

 

 

 

Ignition

 

Ignition

 

 

 

 

 

 

Spark Plug Gap

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston Ring

.006

 

.152

.006

 

.152

.006

 

.152

.007

 

.178

.006

 

.152

End Gap

.016

 

.406

.016

 

.406

.016

 

.406

.017

 

.432

.016

 

.406

Piston

2.0865

 

52.997

2.0865

 

52.997

2.0882

 

53.04

2.4307

 

61.74

2.0880

 

53.035

Diameter

2.0875

 

53.023

2.0875

 

53.023

2.0887

 

53.05

2.4317

 

61.765

2.0885

 

53.049

(Top)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

 

 

 

 

 

 

(Bot.)

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

Width

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

.4999

 

12.698

.4999

 

12.698

.4999

 

12.698

.4999

 

12.698

.4999

 

12.698

Crank Pin Journal

.8113

 

20.607

.8445

 

21.450

.8113

 

20.607

.6922

 

17.582

.8445

 

21.450

Diameter

.8118

 

20.620

.8450

 

21.463

.8118

 

20.620

.6927

 

17.595

.8450

 

21.463

Crankshaft

.9998

 

25.395

.9993

 

25.295

.7498

 

19.045

.6695

 

17.005

.9998

 

25.395

P.T.O. Side

1.0003

 

25.408

1.0003

 

25.408

.7503

 

19.058

.6699

 

17.015

1.0003

 

25.408

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

.8748

 

22.22

.6695

 

17.005

Magneto Side

.6699

 

17.015

.6699

 

17.015

.6699

 

17.015

.8753

 

22.233

.6699

 

17.015

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.003

 

.076

.003

 

.076

None

 

None

None

 

None

.003

 

.076

End Play

.016

 

.406

.016

 

.406

 

 

 

 

 

 

.016

 

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

59

TABLE OF SPECIFICATIONS

Reference Column

38

 

39

 

 

40

 

41

42

 

 

U.S.

 

Metric

U.S.

Metric

U.S.

 

Metric

U.S.

 

Metric

U.S.

 

Metric

 

 

 

mm

 

mm

 

 

mm

 

 

mm

 

 

mm

Bore

2.093

 

53.162

2.093

53.162

2.093

 

53.162

2.093

 

53.162

2.093

 

53.162

 

2.094

 

53.188

2.094

53.188

2.094

 

53.188

2.094

 

53.188

2.094

 

53.188

Stroke

1.828

 

46.431

1.500

38.1

1.828

 

46.431

1.746

 

44.348

1.500

 

38.1

Cu. In. Displacement

6.0

 

98.3

5.20

85.2

6.0

 

98.3

6.0

 

98.3

5.20

 

85.2

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

*

 

 

.020

.508

.020

 

.508

*

 

 

.020

 

.508

Timing

Ext.

 

Ext.

.088

2.235

.070

 

1.778

Ext.

 

Ext.

Ext.

 

Ext.

B.T.D.C.

Ignition

 

Ignition

 

 

 

 

 

Ignition

 

Ignition

Ignition

 

Ignition

Spark Plug Gap

.030

 

.762

.030

.762

.030

 

.762

.030

 

.762

.030

 

.762

Piston Ring

.006

 

.152

.006

.152

.006

 

.152

.006

 

.152

.006

 

.152

End Gap

.016

 

.406

.016

.406

.016

 

.406

.016

 

.406

.016

 

.406

Piston

2.0880

 

53.035

2.0880

53.035

2.0880

 

53.035

2.0880

 

53.035

2.0880

 

53.035

Diameter

2.0885

 

53.049

2.0885

53.049

2.0885

 

53.049

2.0885

 

53.049

2.0885

 

53.049

(Top)

.0655

 

1.664

.0655

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0665

 

1.689

.0665

1.689

.0665

 

1.689

.0665

 

1.689

.0665

 

1.689

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

.0645

 

1.638

.0645

1.638

.0645

 

1.638

.0645

 

1.638

.0645

 

1.638

 

 

 

 

 

(Bot.)

.0655

 

1.664

.0655

1.664

.0655

 

1.664

.0655

 

1.664

.0655

 

1.664

Piston Ring

.0615

 

1.562

.0615

1.562

.0615

 

1.562

.0615

 

1.562

.0615

 

1.562

Width

.0625

 

1.587

.0625

1.587

.0625

 

1.587

.0625

 

1.587

.0625

 

1.587

Piston Pin

.4997

 

12.692

.4997

12.692

.4997

 

12.692

.4997

 

12.692

.4997

 

12.692

Diameter

.4999

 

12.697

.4999

12.697

.4999

 

12.697

.4999

 

12.697

.4999

 

12.697

Crank Pin Journal

.8113

 

20.607

.8113

20.607

.8445

 

21.450

.8113

 

20.607

.8113

 

20.607

Diameter

.8118

 

20.620

.8118

20.620

.8450

 

21.463

.8118

 

20.620

.8118

 

20.620

Crankshaft

.9998

 

25.395

.9998

25.395

.9998

 

25.395

.9998

 

25.395

.7498

 

19.045

P.T.O. Side

1.0003

 

25.408

1.0003

25.408

1.0003

 

25.408

1.0003

 

25.408

.7503

 

19.058

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.7498

 

19.045

.6695

17.005

.6695

 

17.005

.6695

 

17.005

.6695

 

17.005

Magneto Side

.7503

 

19.058

.6699

17.015

.6699

 

17.015

.6699

 

17.015

.6699

 

17.015

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

 

None

None

None

None

 

None

None

 

None

None

 

None

End Play

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

* Does not apply to units with Solid State Ignition.

60

TABLE OF SPECIFICATIONS

Specification

43

AV520

AV600

AH600

HSK600

TVS600

 

U.S.

Metric

U.S.

Metric

U.S.

Metric

U.S.

Metric

U.S.

Metric

U.S.

Metric

 

 

mm

 

mm

 

mm

 

mm

 

mm

 

mm

Bore

2.093

53.162

2.09

53

2.09

53

2.09

53

2.09

53

2.09

53

 

2.094

53.188

 

 

 

 

 

 

 

 

 

 

Stroke

1.5

38.1

1.5

38

1.75

44

2.09

44

1.75

44

1.75

44

Cu. In. Displacement

5.20

85.2

5.2

85 cc

6.0

98 cc

6.0

98 cc

6.0

98 cc

6.0

98 cc

(in3) (cc)

 

 

 

 

 

 

 

 

 

 

 

 

Point Gap

.020

.508

 

 

 

 

 

 

 

 

 

 

Timing

Ext.

Ext.

 

 

 

 

 

 

 

 

 

 

B.T.D.C.

Ignition

Ignition

 

 

 

 

 

 

 

 

 

 

Ignition Module

 

 

.0125

.3175

.0125

.3175

.0125

.3175

.0125

.3175

.0125

.3175

Air Gap

 

 

 

 

 

 

 

 

 

 

 

 

Spark Plug Gap

.030

.762

.030

.762

.030

.762

.030

.762

.030

.762

.030

.762

Piston Ring

.006

.152

.006

.152

.006

.152

.006

.152

.006

.152

.006

.152

End Gap

.016

.406

.016

.406

.016

.406

.016

.406

.016

.406

.016

.406

Piston

2.0880

53.035

2.0877

53.03

2.0877

53.03

2.0877

53.03

2.0877

53.03

2.0877

53.03

Diameter

2.0885

53.049

2.0882

53.04

2.0882

53.04

2.0882

53.04

2.0882

53.04

2.0882

53.04

(Top)

.0655

1.664

.0655

1.664

.0655

1.664

.0655

1.664

.0655

1.664

.0655

1.664

Piston Ring

.0665

1.689

.0665

1.689

.0665

1.689

.0665

1.689

.0665

1.689

.0665

1.689

 

 

 

 

 

 

 

 

 

 

 

 

Groove Width

 

 

 

 

 

 

 

 

 

 

 

 

.0645

1.638

.0655

1.664

.0655

1.664

.0655

1.664

.0655

1.664

.0655

1.664

 

(Bot.)

.0655

1.664

.0665

1.689

.0665

1.689

.0665

1.689

.0665

1.689

.0665

1.689

Piston Ring

.0615

1.562

.0615

1.562

.0615

1.562

.0615

1.562

.0615

1.562

.0615

1.562

Width

.0625

1.587

.0625

1.587

.0625

1.587

.0625

1.587

.0625

1.587

.0625

1.587

Piston Pin

.4997

12.692

.5005

12.713

.5005

12.713

.5005

12.713

.5005

12.713

.5005

12.713

Diameter

.4999

12.697

.5007

12.718

.5007

12.718

.5007

12.718

.5007

12.718

.5007

12.718

Crank Pin Journal

.6922

17.582

.8445

21.450

.8445

21.450

.8445

21.450

.8445

21.450

.8445

21.450

Diameter

.6927

17.595

.8450

21.463

.8450

21.463

.8450

21.463

.8450

21.463

.8450

21.463

Crankshaft

.7498

19.045

.9998

25.395

.9998

25.395

.7498

19.045

.7498

19.045

.9998

25.395

P.T.O. Side

.7503

19.058

1.0003

25.408

1.0003

25.408

.7503

19.058

.7503

19.058

1.0003

25.408

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

.6695

17.005

.6695

17.005

.6695

17.005

.6695

17.005

.6695

17.005

.6695

17.005

Magneto Side

.6699

17.015

.6699

17.015

.6699

17.015

.6699

17.015

.6699

17.015

.6699

17.015

Main Brg. Dia.

 

 

 

 

 

 

 

 

 

 

 

 

Crankshaft

None

None

.003

.076

.003

.076

.003

.076

.003

.076

.003

.076

End Play

 

 

.016

.406

.016

.406

.016

.406

.016

.406

.016

.406

 

 

 

 

 

 

 

 

 

 

 

 

 

61

TABLE OF TORQUE LIMITS

 

INCH POUNDS

NEWTON METERS

 

 

 

Cylinder

80 - 100

9 - 11

 

 

 

 

 

Flywheel Nut

264

- 324

30

- 37

 

 

 

 

 

Connecting Rod Screws

 

 

 

 

Aluminum Rods

40

- 50

4.5

- 5.5

Steel Rods

70

- 80

8

- 9

 

 

 

 

Spark Plug

192

- 264

21.5 - 30

 

 

 

 

Fuel Tank Screws

12

- 20

1.5 - 2

 

 

 

Blower Housing Mounting Screws

80 - 100

9-11

 

 

 

Muffler Mounting Screws

80 - 100

9 - 11

 

 

 

 

Muffler Cover (Snowthrowers)

20

- 30

2 - 3.5

 

 

 

Stator to Base (Except Outboards)

80 - 100

9 - 11

 

 

 

 

 

External Screws to Laminations

30

- 40

3.5

- 4.5

 

 

 

 

Point Screw

15

- 25

1.5 - 3

 

 

 

 

 

Air Filter or Carburetor Baffle (Metal)

30

- 40

3.5

- 4.5

 

 

 

 

 

Air Filter (Plastic)

18

- 25

2

- 3

 

 

 

 

Carburetor Mounting Nuts

60

- 75

7- 8.5

 

 

 

 

Reed Plate, Cover Plate

35

- 45

4-5

 

 

 

 

Reed Hold down

15

- 25

1.5- 3

 

 

 

 

 

Compression Release Cover

30

- 40

3.5

- 4.5

 

 

 

Shroud Base to Block

80 - 100

9 - 11

 

 

 

 

Starter Mounting Screws (Metal)

50

- 70

5.5- 8

 

 

 

 

 

Starter Mounting Screws (Plastic)

30

- 40

3.5

- 4.5

 

 

 

 

 

Electric Starter Mounting Screws

65

- 85

7.5

- 9.5

 

 

 

Stop Lever to Head

80 - 100

9 - 11

 

 

 

 

 

Speed Control to Shroud Base

30

- 40

3.5

- 4.5

 

 

 

 

 

Compliance Brake Bracket to Cylinder

60

- 80

7

- 9

 

 

 

 

Compliance Brake Bracket to Base

35

- 50

4 - 5.5

 

 

 

 

 

"Torque specifications listed on this page should not be confused with the torque value observed on engines which have been run. Torque relaxation occurs on all engines from thermal expansion and contraction. The torque specifications take relaxation into account so a sufficient clamping force exists after an engine has been run.”

62

EDUCATIONAL MATERIALS AND TOOLS

AVAILABLE TECHNICIAN'S HANDBOOKS 692508

Covers the diagnosis and repair of Tecumseh 2-cycle engines. Except the TC Engine and TVS840.

692509

Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines.

691462A

Covers the diagnosis and repair of Tecumseh 4-cycle large frame engines.

691218

Covers the diagnosis and repair of Peerless® power train components.

694782

Contains technical information for the repair of the TC series, 2-cycle engines.

694988

Contains diagnosis and technical information for the repair of TVS840, HSK/HXL845/850, 2-cycle engines. 695244A

Covers the diagnosis and repair of the OVRM/OVM/ OHH/OHM/OHV 4-cycle overhead valve engines. 695578

Covers the diagnosis and repair of the Vector Series, 4-cycle engines.

AVAILABLE FOREIGN TECHNICIAN'S

HANDBOOKS

694732 Spanish

This manual covers the following models:

VH80, VH100, HH80, HH100, HH120, OH120-180 Model numbers are located on the engine shroud. 695555 Spanish

Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines.

695657 German

Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines.

695562 French

Covers the diagnosis and repair of the Tecumseh 4-cycle light/medium frame engines.

VIDEO PROGRAMS

695015

Carburetor Troubleshooting. Covers identification of carburetors used on Tecumseh engines and how to troubleshoot and repair them. VHS only.

695059

Understanding Tecumseh Ignition Systems. A basic program designed to give the small engine technician first hand knowledge of Tecumseh ignition systems so the technician can understand the system and perform repairs to it. VHS only.

695148

Teardown and reassembly of the 900 series transaxles. This video will show a complete step-by-step procedure for teardown and reassembly of the 900, 910 and 920 series transaxles.

695185

Electrical Troubleshooting. This video training program will assist the small engine technician in the proper procedures for troubleshooting electrical systems on outdoor power equipment.

695285

An in-depth look at the 800 series transaxles. Detailing the teardown and reassembly procedures for the 800, 801 and 820 transaxles.

SPECIALTY / TROUBLESHOOTING BOOKLETS

INSTRUCTIONAL GUIDE

692738

Assists in the use and understanding of the Tecumseh Master Parts Manual. Illustrates time saving features incorporated into the manual. Explains new carburetor parts breakdown format.

4-CYCLE ENGINE FAILURE ANALYSIS

695590

This booklet is designed as a tool for the average technician to correctly assess the cause of failure.

CARBURETOR TROUBLESHOOTING BOOKLET 695907

This booklet is designed as a quick reference to carburetion problems and related repair procedures.

IGNITION SYSTEMS TROUBLESHOOTING BOOKLET 694903

This booklet contains information on the identification, possible problems and related repair procedures of Tecumseh Ignition Systems.

SPECIAL TOOLS BOOKLET

694862

This booklet depicts all specialty tools offered by Tecumseh which can be used on 2 and 4 cycle engines and Peerless units.

QUICK REFERENCE CHART BOOKLET 695933

This booklet contains the quick reference information found on Tecumseh wall charts.

This booklet is designed to be used as a work bench quick reference guide when servicing Tecumseh engines and motion drive systems.

TESTER BOOKLETS

694529

Test procedures for Tecumseh electrical components using Graham-Lee Tester 31-SM or 31-SMX-H.

694530

Test procedures for Tecumseh electrical components using Merco-O-Tronic Tester 9800. (Tests are similar for 98, 98A and 79.)

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OIL SEAL DRIVER - PROTECTOR

DIAL INDICATOR

Extra Tips:

Large Head No. 670250

Thin Head No. 670249

Leg and Screw No. 670296

No. 670241 - Dial Indicator.

OIL SEAL REMOVER

No. 670286. Used on P.T.O. end of single cylinder outboards with one piece oil seals. Includes tool No. 670285 and center screw.

No. 670291. Used on magneto end of all two cycle engines with one piece oil seals and P.T.O. end of 1600 series. Includes tool No. 670280 and center screw.

No. 670257. Used on 2 cycle connecting rod screws.

No. 670307. Used on 590556 electric starter mounting screws.

TORX® E-6 SOCKET

TORX® E-8 SOCKET

No. 670257

No. 670307

 

 

 

BALL BEARING DRIVER

No. 670258

PISTON RING EXPANDER

No. 670117 - Piston ring expander

TAPER GAP GAUGE

No. 670256 - Taper Gap Gauge

VIBRATION TACHOMETER

No. 670156 - Vibration tachometer.

No. 670298 - Aligning Pin