Parts Lookup    Parts by Category


Tecumseh 2 Cycle Repair Manual AH520 AH600 AV520 AV600 HSK600 TVS600


Tecumseh Parts   |   Tecumseh Parts Lookup   |   Tecumseh Repair Manuals


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.

<