TECUMSEH OHH50 - 65, OHHSK50 - 130, OHV11, OVM120, OVRM40-675 User Manual

...

TECUMSEH

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

This manual covers engine models:

OHH50 - 65, OHHSK50 - 130, OHV11 - OHV17, OVM120,

OVRM40-675, OVRM120, OVXL/C120, OVXL120, OVXL125.

Other illustrated Tecumseh 2-Cycle Engine, 4-Cycle Engine and

Transmission manuals; booklets; and wall charts are available

through Tecumseh.

For complete listing write or call

CONTAINS SEARS CRAFTSMAN CROSS REFERENCE

4-CYCLE OVERHEAD

VALVE ENGINES

Small Engine Parts

CONTENTS

Page

CHAPTER 1 GENERAL INFORMATION ....................... 1

ENGINE IDENTIFICATION ............................................. 1

INTERPRETATION OF MODEL NUMBER ..................... 1

SHORT BLOCKS............................................................. 2

FUELS ............................................................................. 2

ENGINE OIL .................................................................... 2

CAPACITIES.................................................................... 2

OIL CHANGE INTERVALS .............................................. 3

OIL CHECK...................................................................... 3

OIL CHANGE PROCEDURE .......................................... 3

TUNE-UP PROCEDURE ................................................. 3

STORAGE ....................................................................... 4

DRAINING THE FUEL SYSTEM ..................................... 4

OIL CYLINDER BORE .................................................... 4

CHAPTER 2 AIR CLEANERS ....................................... 5

GENERAL INFORMATION ............................................. 5

OPERATION .................................................................... 5

COMPONENTS ............................................................... 5

TROUBLESHOOTING OR TESTING ............................. 6

SERVICE ......................................................................... 6

DISASSEMBLY PROCEDURE ....................................... 6

POLYURETHANE-TYPE FILTER ELEMENT

OR PRE-CLEANER..................................................... 7

PAPER -TYPE FILTER ELEMENT ................................. 7

FLOCKED SCREEN........................................................ 7

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS . 8

GENERAL INFORMATION ............................................. 8

OPERATION .................................................................... 8

FUEL PRIMERS .............................................................. 9

IMPULSE FUEL PUMPS ................................................. 9

FLOAT STYLE CARBURETORS .................................... 9

CARBURETOR VISUAL IDENTIFICATION .................... 10

SERIES I CARBURETORS............................................. 10

SERIES III & SERIES IV CARBURETORS .................... 10

SERIES VI CARBURETORS .......................................... 10

SERIES VII ...................................................................... 10

SERIES VIII ..................................................................... 11

SERIES IX ....................................................................... 11

WALBRO MODEL LMK ................................................... 11

TESTING ......................................................................... 12

SERVICE ......................................................................... 12

CARBURETOR PRE-SETS AND ADJUSTMENTS........ 12

PRE-SETS AND ADJUSTMENTS

(TECUMSEH AND WALBRO CARBURETORS)......... 13

FINAL ADJUSTMENTS ................................................... 13

TECUMSEH CARBURETORS ........................................ 13

WALBRO CARBURETOR ............................................... 13

CARBURETOR DISASSEMBLY PROCEDURE ............. 14

IMPULSE FUEL PUMP ................................................... 15

FLOAT ADJUSTING PROCEDURE................................ 16

INSPECTION ................................................................... 16

THROTTLE AND CHOKE ............................................... 16

IDLE AND HIGH SPEED MIXTURE ADJUSTING

SCREW ........................................................................ 16

FUEL BOWL RETAINING NUT ....................................... 16

FUEL BOWL, FLOAT, NEEDLE AND SEAT ................... 17

ASSEMBLY PROCEDURE ............................................. 18

WELCH PLUGS............................................................... 18

THROTTLE SHAFT AND PLATE .................................... 18

CHOKE SHAFT AND PLATE .......................................... 19

FUEL INLET FITTING ..................................................... 19

HIGH AND LOW SPEED ADJUSTING SCREW,

MAIN NOZZLE ............................................................. 19

Page

INLET NEEDLE AND SEAT ............................................ 20

FLOAT INSTALLATION ................................................... 20

FUEL BOWL AND BOWL NUT ....................................... 21

IMPULSE FUEL PUMP ................................................... 21

PRIMER BULB ................................................................ 21

FINAL CHECKS............................................................... 21

CHAPTER 4 GOVERNORS AND LINKAGE ................. 22

GENERAL INFORMATION ............................................. 22

OPERATION .................................................................... 22

TROUBLESHOOTING .................................................... 22

ENGINE OVERSPEEDING ............................................. 22

ENGINE SURGING ......................................................... 22

SERVICE ......................................................................... 23

GOVERNOR ADJUSTMENT .......................................... 23

GOVERNOR GEAR AND SHAFT SERVICE .................. 23

GOVERNOR GEAR OR SHAFT REPLACEMENT,

UPSET STYLE GOVERNOR SHAFT .......................... 23

GOVERNOR SHAFT REPLACEMENT, RETAINING

RING STYLE ................................................................ 24

SPEED CONTROLS AND LINKAGE .............................. 25

CONVERSION TO REMOTE CONTROL ....................... 27

OVM, OVXL, OHV VERTICAL SPEED CONTROL ........ 28

OHV 11-17 HORIZONTAL SPEED CONTROL............... 28

CHAPTER 5 RECOIL STARTERS ................................. 29

GENERAL INFORMATION ............................................. 29

OPERATION .................................................................... 29

COMPONENTS ............................................................... 29

SERVICE ......................................................................... 29

ROPE SERVICE .............................................................. 29

ROPE RETAINER REPLACEMENT ............................... 30

STYLIZED REWIND STARTER (OHH, OVRM, OHM, OHSK, OVM, OVXL, OHV 11-13), AND STAMPED

STEEL STARTER ......................................................... 30

DISASSEMBLY PROCEDURE ....................................... 30

ASSEMBLY PROCEDURE ............................................. 31

STYLIZED REWIND STARTER WITH PLASTIC

RETAINER.................................................................... 31

DISASSEMBLY PROCEDURE ....................................... 31

ASSEMBLY...................................................................... 32

KEEPER SPRING STYLE STARTERS .......................... 32

DISASSEMBLY PROCEDURE ....................................... 32

ASSEMBLY PROCEDURE ............................................. 33

STYLIZED STARTER (OHV 13.5 -17) ............................ 34

ASSEMBLY...................................................................... 34

CHAPTER 6 ELECTRICAL SYSTEMS .......................... 35

GENERAL INFORMATION ............................................. 35

OPERATION .................................................................... 35

STARTING CIRCUIT AND ELECTRIC STARTERS ....... 35

CHARGING CIRCUIT ...................................................... 35

CONVERTING ALTERNATING CURRENT TO

DIRECT CURRENT ...................................................... 36

HALF WAVE RECTIFIER SINGLE DIODE..................... 36

FULL WAVE RECTIFIER BRIDGE RECTIFIER ............. 36

COMPONENTS ............................................................... 36

BATTERY......................................................................... 36

WIRING............................................................................ 36

ELECTRICAL TERMS ..................................................... 37

BASIC CHECKS .............................................................. 37

TROUBLESHOOTING ELECTRICAL STARTER

CIRCUIT FLOW CHART .............................................. 38

TROUBLESHOOTING ELECTRICAL CHARGING

CIRCUIT FLOW CHART .............................................. 39

C Tecumseh Products Company

1998

Page

TESTING PROCEDURE ................................................. 40

STARTING CIRCUIT ....................................................... 40

CHARGING CIRCUIT ...................................................... 40

350 MILLIAMP CHARGING SYSTEM ............................ 40

18 WATT A.C. LIGHTING ALTERNATOR....................... 41

35 WATT A.C. .................................................................. 41

2.5 AMP D.C., 35 WATT LIGHTING ............................... 41

3 AMP DC ALTERNATOR SYSTEM - DIODE IN

HARNESS SLEEVE ..................................................... 42

5 AMP D.C. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER BLOWER

HOUSING ..................................................................... 43

3 AMP D.C. 5 AMP A.C. ALTERNATOR ......................... 43

MODELS OVM/OVXL/OHV12.5 ..................................... 44

MODELS OHV 13.5 - 17 (3/5 AMP SPLIT)..................... 44

MODELS OVM/OVXL/OHV12.5

(RED BETWEEN ENGINE AND DIODE) .................... 44

MODELS OHV 13.5 - 17

(RED BETWEEN ENGINE AND DIODE) .................... 45

7 AMP D.C. ALTERNATOR SYSTEM REGULATOR-RECTIFIER UNDER ENGINE

HOUSING ..................................................................... 45

10 AMP A.C. ALTERNATOR ........................................... 46

16 AMP ALTERNATOR SYSTEM WITH EXTERNAL

REGULATOR................................................................ 46

VOLTAGE REGULATORS .............................................. 46

FUEL SHUT-DOWN SOLENOIDS .................................. 46

LOW OIL SHUTDOWN SWITCHES ............................... 47

LOW OIL PRESSURE SENSOR .................................... 47

LOW OIL SENSOR.......................................................... 47

ELECTRIC STARTER SERVICE .................................... 48

12 VOLT OR 120 VOLT ELECTRIC STARTERS ........... 48

INSPECTION AND REPAIR............................................ 49

BRUSH CARD REPLACEMENT..................................... 49

CHAPTER 7 FLYWHEEL BRAKE SYSTEMS ............... 50

GENERAL INFORMATION ............................................. 50

OPERATION .................................................................... 50

COMPONENTS ............................................................... 51

SERVICE ......................................................................... 51

BRAKE BRACKET ASSEMBLY ...................................... 52

IGNITION GROUNDOUT TERMINAL............................. 52

STARTER INTERLOCK SWITCH ................................... 52

CONTROL CABLE .......................................................... 52

BRAKE BRACKET REPLACEMENT .............................. 52

CHAPTER 8 IGNITION ................................................... 53

GENERAL INFORMATION ............................................. 53

OPERATION .................................................................... 53

SOLID STATE IGNITION SYSTEM (CDI) ....................... 53

COMPONENTS ............................................................... 53

TESTING PROCEDURE ................................................. 54

FOUR CYCLE IGNITION TROUBLESHOOTING........... 55

SERVICE ......................................................................... 56

SPARK PLUG SERVICE ................................................. 56

CONDITIONS CAUSING FREQUENT SPARK

PLUG FOULING ........................................................... 56

IGNITION TIMING CHECK ............................................. 57

SERVICE TIPS ................................................................ 57

Page

CHAPTER 9 INTERNAL ENGINE AND CYLINDER ..... 58

GENERAL INFORMATION ............................................. 58

OPERATION .................................................................... 58

4-CYCLE ENGINE THEORY .......................................... 58

LUBRICATION SYSTEMS .............................................. 59

COUNTERBALANCE SYSTEMS ................................... 59

COMPONENTS ............................................................... 60

ENGINE OPERATION PROBLEMS ............................... 61

ENGINE OPERATION PROBLEMS ............................... 62

TESTING ......................................................................... 63

ENGINE KNOCKS ........................................................... 63

ENGINE OVERHEATS.................................................... 63

SURGES OR RUNS UNEVENLY ................................... 63

ENGINE MISFIRES ......................................................... 63

ENGINE VIBRATES EXCESSIVELY .............................. 64

BREATHER PASSING OIL ............................................. 64

EXCESSIVE OIL CONSUMPTION ................................. 64

LACKS POWER .............................................................. 65

SERVICE ......................................................................... 65

DISASSEMBLY PROCEDURE ....................................... 65

CYLINDERS .................................................................... 68

CYLINDER HEAD AND VALVE TRAIN SERVICE ......... 69

VALVES, SPRINGS, AND PUSH RODS ........................ 69

PISTONS, RINGS, AND CONNECTING RODS............. 70

PISTON ........................................................................... 70

PISTON RINGS ............................................................... 70

PISTON RING ORIENTATION ....................................... 70

CONNECTING RODS ..................................................... 71

CRANKSHAFTS AND CAMSHAFTS .............................. 71

CAMSHAFTS................................................................... 71

VALVE SEATS ................................................................. 72

VALVE LIFTERS.............................................................. 73

VALVE GUIDES ............................................................... 73

VALVE GUIDE REMOVAL (OVM, OHM, OHSK110

& 120, OVXL ONLY) .................................................... 73

VALVE GUIDE INSTALLATION (OVM, OHM,

OHSK110 & 120, OVXL ONLY) ................................... 73

CRANKCASE BREATHERS ........................................... 74

TOP MOUNTED BREATHER ......................................... 74

SIDE MOUNTED BREATHER ........................................ 74

CYLINDER COVER, OIL SEAL, AND BEARING

SERVICE ...................................................................... 75

CYLINDER COVER ........................................................ 75

OIL SEAL SERVICE........................................................ 75

CRANKSHAFT BEARING SERVICE .............................. 75

BALL BEARING SERVICE.............................................. 75

SERVICE BUSHING ....................................................... 76

BUSHING SIZE CHART.................................................. 76

ENGINE ASSEMBLY ...................................................... 76

CHAPTER 10 .................................................................. 83

ENGINE SPECIFICATIONS AND SEARS

CRAFTSMAN CROSS-REFERENCE ......................... 83

OVERHEAD VALVE SEARS CRAFTSMAN

CROSS REFERENCE ................................................. 83

ENGINE SPECIFICATIONS............................................ 85

OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 86

OVERHEAD VALVE TORQUE SPECIFICATIONS ........ 87

CHAPTER 11 EDUCATIONAL MATERIALS

AND TOOLS ............................................................... 88

All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without permission in writing from Tecumseh Products Company Training Department Manager.

CHAPTER 1 GENERAL INFORMATION

ENGINE IDENTIFICATION

Tecumseh engine model, specification, and serial numbers or date of manufacture (D.O.M.) are stamped into the blower housing, or located on a decal on the engine in locations as illustrated (diag. 1 & 2). The engine identification decal also provides the applicable warranty code and oil recommendations (diag. 2).

Interpretation of Model Number

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

OHH - Overhead Valve Horizontal OHM - Overhead Valve Horizontal

MediumFrame OHSK - Overhead Valve Horizontal Snow King OVM - Overhead Valve Vertical Medium Frame OVRM - Overhead Valve Vertical Rotary Mower OVXL - Overhead Valve Vertical Medium Frame

Extra Life OHV - Overhead Valve Vertical

ENGINE MODEL

NUMBER

The number designations following the letters indicate the basic engine model.

The number following the model number is the specification number. The last three numbers of the specification number indicate a variation to the basic engine specification.

The serial number or D.O.M. indicates the production date of the engine.

Using model OHV16-204207A, serial 5215C as an example, interpretation is as follows:

OHV16-204207A is the model and specification number.

OHV Overhead Valve Vertical 16 Indicates the basic engine model. 204207A is the specification number used for

properly identifying the parts of the engine.

5215C is the serial number or D.O.M. (Date of

Manufacture)

5 is the last digit in the year of

manufacture (1995).

215 indicates the calendar day of that year

(215th day or August 3, 1995).

C represents the line and shift on which

the engine was built at the factory.

THIS ENGINE MEETS 1995-1998

CALIF. EMISSION REGULATIONS FOR

ULGE ENGINES AS APPLICABLE

FUEL: REGULAR UNLEADED OIL : USE SAE 30

OHV 125 203000A (D) RTP358UIG2RA 358cc 3057D

Emissionized engines that meet the California Air Resource Board (C.A.R.B.) or the Environmental Protection Agency (E.P.A.) standards will include additional required engine information on the engine decal.

NOTE: To maintain best possible emission performance, use only Genuine Tecumseh Parts.

SHORT BLOCKS

SBV OR SBH IDENTIFICATION NUMBER

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 (diag. 3).

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

SHORT BLOCK IDENTIFICATION TAG

SBV- 564A SER 5107

SERIAL NUMBER

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 combustion chamber deposits. Unleaded regular, unleaded premium or reformulated gasoline containing no more than 10% Ethanol, or 15% MTBE, or 15% ETBE may also be used.

Leaded fuel is generally not available in the United States and should not be used if any of the above options are available.

Never use gasoline, fuel conditioners, additives or stabilizers containing methanol, white gas, or fuel blends which exceed the limits specified above for Ethanol, MTBE, or ETBE because engine/fuel system damage could result.

Regardless of which of the approved fuels are used, fuel quality is critical to engine performance. Fuel should not be stored in an engine or container more than 30 days prior to use. This time may be extended with the use of a fuel stabilizer like TECUMSEH'S, part number 730245.

See "STORAGE" instructions in the Technician's Manual, Operators Manual, or Bulletin 111.

ENGINE OIL

TECUMSEH FOUR CYCLE ENGINES REQUIRE THE USE OF A CLEAN, HIGH QUALITY DETERGENT OIL. Be sure original container is marked: A.P.I. service "SF" thru "SJ" or "CD".

TECUMSEH RECOMMENDS USING ONE OF THE FOLLOWING FOUR CYCLE OILS THAT ARE SPECIALLY FORMULATED TO TECUMSEH SPECIFICATIONS.

DO NOT USE SAE10W40 OIL. FOR SUMMER (Above 320 F) (0oC) USE SAE30 OIL. PART #730225

Use SAE30 oil in high temperature, high load applications. Using multigrade oil may increase oil consumption. FOR WINTER (Below 320F) (0oC) USE SAE5W30 OIL. PART #730226 (SAE 10W is an acceptable substitute.) (BELOW 00F (-18oC) ONLY): SAE 0W30 is an acceptable substitute.

NOTE: For severe, prolonged winter operation of HH120 model, SAE10W oil is recommended.

Capacities

Engine Model Oz. ml.

OHH,OHSK 50-70 21 630 OVRM 40 - 6.75 21 630 OVRM105 & 120 21 630 OHSK80 - 100 26 720 OHM, OHSK 110* - 130 32 960 OVM 120, OVXL 120, 125 32 960 OHV 11 - 13 without oil filter 32 960 OHV 11 - 13 with filter 39 1170 OHV 13.5 - 17 without oil filter 55 1650 OHV 13.5 -17 2 1/4" filter (part # 36563) 62 1860 OHV 13.5 -17 2 5/8" filter (part # 36262) 64 1920

* NOTE: Model OHSK110 with a spec. of 221000 and up, have a capacity of 26 oz. (720 ml.)

Oil Change Intervals: Change the oil after the first two (2) hours of operation and every 25 hours thereafter

(OHH & OHSK50-130, OHV13.5-17 every 50 hours), or more often if operated under dusty or dirty conditions. If the engine is run less than 25 hours per year, change the oil at least once per year.

NOTE: The oil filter (if equipped) requires changing every 100 hours or more often if operated under dusty or dirty conditions.

Oil Check: Check the oil each time the equipment is used or every five (5) hours of operation. Position the

equipment so the engine is level when checking the oil.

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

Oil Change Procedure: Locate the oil drain plug. On some units this plug is located below the deck

through the bottom of the mounting flange. Other units drain at the base of the engine above the deck or frame. On some rotary mower applications, where access to the drain plug is restricted by the equipment, it may be necessary to drain the oil by tipping the mower in a position that would allow the oil to drain out of the fill tube.

On units that the drain plug is accessible, remove the plug and allow the oil to drain into a proper receptacle. Always make sure that drain oil is disposed of properly. Contact your local governing authorities to find a waste oil disposal site.

Once the oil is drained, reinstall the drain plug and fill the engine with new oil to the proper capacity.

TUNE-UP PROCEDURE:

NOTE: Today's fuels can cause many problems in an engines performance due to the fuels quality and short

shelf life. Always check fuel as a primary cause of poor engine performance. The following is a minor tune-up procedure. When this procedure is completed, the engine should operate

properly. Further repairs may be necessary if the engine's performance remains poor.

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

1. Service or replace the air cleaner. See Chapter 2 under "Service".

2. Inspect the level and condition of the oil and change or add oil as required.

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

4. Make sure the fuel tank, fuel filter and fuel line are clean. Replace any worn or damaged governor springs or linkage. Make the proper governor adjustments and carburetor presets where required.

5. When replacing the spark plug, consult the proper parts breakdown for the spark plug to be used in the engine being serviced. Set the proper spark plug gap (.030") (.762 mm) and install the spark plug in the engine. Tighten the spark plug to 21 foot pounds (28 Nm) of torque. If a torque wrench isnt available, screw the spark plug in as far as possible by hand, and use a spark plug wrench to turn the spark plug 1/8 to 1/4 turn further if using the old spark plug, or 1/2 turn further if using a new spark plug.

STANDARD PLUG

OHV

6. Make sure all ignition wires are free of abrasions or breaks and are properly routed so they will not rub on the flywheel.

7. Properly reinstall the blower housing, gas tank, fuel line, and air cleaner assembly if removed.

8. Make sure all remote cables are properly adjusted for proper operation. See Chapter 4 under "Speed Controls and Linkage".

9. Reinstall the spark plug wire, add fuel and oil as necessary, start the engine.

STORAGE (IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE)

CAUTION: NEVER STORE THE ENGINE WITH FUEL IN THE TANK INDOORS OR IN ENCLOSED, POORLY VENTILATED AREAS, WHERE FUEL FUMES MAY REACH AN OPEN FLAME, SPARK OR PILOT LIGHT AS ON A FURNACE, WATER HEATER, CLOTHES DRYER OR OTHER GAS APPLIANCE.

Gasoline can become stale in less than 30 days and form deposits that can impede proper fuel flow and engine operation. To prevent deposits from forming, all gasoline must be removed from the fuel tank and the carburetor. An acceptable alternative to removing all gasoline, is by adding Tecumseh's fuel stabilizer, part number 730245, to the gasoline. Fuel stabilizer is added to the fuel tank or storage container. Always follow the mix ratio found on the stabilizer container. Run the engine at least 10 minutes after adding

the stabilizer to allow it to reach the carburetor.

Draining the Fuel System

CAUTION: DRAIN THE FUEL INTO AN APPROVED CONTAINER OUTDOORS, AND AWAY FROM ANY OPEN FLAME OR COMBUSTION SOURCE. BE SURE THE ENGINE IS COOL.

1. Remove all gasoline from the fuel tank by running the engine until the engine stops, or by draining the fuel tank by removing the fuel line at the carburetor or fuel tank. Be careful not to damage the fuel line, fittings, or fuel tank.

2. Drain the carburetor by pressing upward on bowl drain (if equipped) which is located on the bottom of the carburetor bowl. On carburetors without a bowl drain, the carburetor may be drained by loosening the bowl nut on the bottom carburetor one full turn. Allow to completely drain and retighten the bowl nut being careful not to damage the bowl gasket when tightening.

3. If "Gasohol" has been used, complete the above procedure and then put one half pint of unleaded gasoline into the fuel tank and repeat the above procedure. If Gasohol is allowed to remain in the fuel system during storage, the alcohol content can cause rubber gaskets and seals to deteriorate.

Change Oil: If the oil has not been changed recently, this is a good time to do it. See "Oil Change Procedure"

on page 3.

Oil Cylinder Bore

1. Disconnect the spark plug wire and ground the spark plug wire to the engine. Remove the spark plug and put a 1/2 ounce (15 ml.) of clean engine oil into spark plug hole.

2. Cover the spark plug hole with a shop towel.

3. Crank the engine over, slowly, several times.

4. Install the spark plug and connect the spark plug wire.

Clean Engine: Remove the blower housing and clean all dirt, grass or debris from the intake screen, head,

cylinder cooling fins, carburetor, governor levers and linkage.

CHAPTER 2 AIR CLEANERS

GENERAL INFORMATION

The air cleaner is the device used to eliminate dust

and dirt from the air supply. Filtered air is necessary

to assure that abrasive particles are removed before

entering the combustion chamber. Dirt allowed into

the engine will quickly wear the internal components

and shorten the life of the engine.

Tecumseh engines use either a polyurethane or a

paper-type air filter system. A polyurethane pre-

cleaner or a flocked screen may be used with the main

filter. Snow King® engines do not use an air filter due

to the clean operating environment and to prevent filter

freeze-up.

Extremely dirty conditions may require more frequent

filter cleaning or replacement.

COVER

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

FOAM

ELEMENT

OPERATION

The air cleaner cover allows access to the air filter

element(s) and prevents large particles from entering

the filter body. Air is filtered through the pre-cleaner

or flocked screen if equipped, and the polyurethane

or paper filter element. Pre-cleaners or flocked

screens provide more air cleaning capacity.

In Tecumseh's Kleen Aire® system, air is drawn in

through a rotating screen or recoil housing to be

centrifugally cleaned by the flywheel before the air

enters the air filter.

COMPONENTS

The cover holds the filter element and prevents large

debris from entering the filter body.

The polyurethane wrap pre-cleaner is used on XL

or XL/C engine models with paper filter elements.

The paper or polyurethane filter element is the main

filter to trap dust and dirt. Dry-type paper elements

are pleated paper for increased surface area and

rubberized sealing edges. The polyurethane filter uses

an oil film to trap fine particles found in dust.

The flocked screen is used as an additional filter on

XL or XL/C engine models that use a polyurethane

filter element.

AIR CLEANER

BODY

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

FLOCKED SCREEN

COVER

POLYURETHENE

WRAP

PAPER

ELEMENT

AIR CLEANER

BODY

TROUBLESHOOTING OR TESTING

If the engine's performance is unsatisfactory (needs excessive carburetor adjustments, starts smoking

abnormally, loses power), the first engine component to be checked is the air filter. A dirt restricted or an oil

soaked filter will cause noticeable performance problems. A polyurethane filter may be cleaned following the

service procedure listed under "Service" in this chapter. A paper-type air filter should only be replaced. A

paper-type filter cannot have an oil film present on the paper. Follow the procedure listed in the "Service"

section of this chapter for filter replacement or cleaning.

SERVICE

Service on the polyurethane filter element (cleaning and oiling) is recommended every three (3) months or

every twenty five (25) operating hours, whichever comes first. Extremely dirty or dusty conditions may require

daily cleanings.

The paper filter element should be replaced once a year or every 100 operating hours, more often if used in

extremely dusty conditions.

NOTE: NEVER RUN THE ENGINE WITHOUT THE COMPLETE AIR CLEANER ASSEMBLY INSTALLED ON

THE ENGINE. ALWAYS REPLACE THE FILTER ELEMENT WITH THE PROPER TECUMSEH ORIGINAL

REPLACEMENT PART.

DISASSEMBLY PROCEDURE

1. Unlock the tabs or remove the screws or wing

nuts holding the air cleaner cover in place.

2. Remove the hex nuts holding the element

down if equipped. New nuts are supplied with

a new filter and are to be used for proper

sealing.

3. Clean the excess contaminants out of the air

cleaner body before removing the old

element.

4. Remove the old element and the polyurethane

pre-cleaner if equipped.

5. On air cleaners that use a flocked screen

under the polyurethane element, remove the

air cleaner assembly from the carburetor

before removing the flocked screen. This

prevents dirt from entering the carburetor

(diag 3).

6. Clean the inside of the cover and body,

remove the old gasket between the carburetor

and the air cleaner assembly.

7. Reinstall the air cleaner assembly using a new

gasket.

8. Use reverse procedure for reassembly. When

installing the polyurethane pre-cleaner, make

sure the seam is installed to the outside to

prevent gaps between the paper element and

the pre-cleaner.

KLEEN-AIRE

ENTRANCE

COVER

FOAM

FILTER

KLEEN-AIRE

ENTRANCE

FILTER A

(FOAM)

WING NUTS

COVER

GASKET

NUTS

FILTER B

BODY

GASKET

FLOCKED SCREEN

GASKET

Polyurethane-Type Filter Element or pre-cleaner

This type of air filter or pre-cleaner can be serviced when restricted with dust or dirt. Wash the filter or pre-

cleaner in a detergent and water solution until all the dirt is removed. Rinse in clear water to remove the

detergent solution. Squeeze the filter or pre-cleaner (do not twist) to remove the excess water. Wrap the filter

or pre-cleaner in a clean cloth and squeeze it (do not twist) until completely dry.

On the polyurethane filter only, re-oil the filter by applying engine oil and squeezing it vigorously to distribute

the oil. Roll the filter in a cloth and squeeze it (do not twist) to remove the excess oil. The pre-cleaner must not

be oiled.

Clean the air cleaner housing and cover being careful not to allow dirt to fall into the carburetor or intake pipe.

Paper -type filter element

Paper type air filter elements can only be serviced by replacement. Do not attempt to clean a paper filter

element. Replacement filters are available at any authorized Tecumseh Service Outlet. Be sure to use new

filter nuts or seals for the air cleaner studs if supplied with the new filter (diag. 5).

Flocked Screen

A flocked screen may be cleaned by blowing compressed air through the screen from the backside. If the

screen cannot be cleaned with this procedure, it should be replaced with a new screen.

COVER

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

AIR CLEANER

BODY

FOAM

ELEMENT

FLOCKED SCREEN

COVER

POLYURETHENE

WRAP

PAPER

ELEMENT

AIR CLEANER

BODY

KLEEN-AIRE

ENTRANCE FROM

UNDER BLOWER

HOUSING

CHAPTER 3 CARBURETORS AND FUEL SYSTEMS

GENERAL INFORMATION

Tecumseh overhead valve engines use float type carburetors. Float type carburetors use a hollow float to

maintain the operating level of fuel in the carburetor.

The float type carburetor will have a fuel enrichment system of either a primer or a manual choke to provide

easy cold engine starting. The carburetor fuel mixtures are either fully adjustable, partially adjustable, or

nonadjustable. Carburetor adjustments, cleaning, and related fuel system service is covered in this chapter.

Some Tecumseh engines utilize Walbro carburetors. Basic operation is very similar to the Tecumseh float style

carburetor.

Carburetors used by Tecumseh can be identified by a manufacturing number stamping on the carburetor as

illustrated (diag. 1).

When servicing carburetors, use the engine model

and specification number to obtain the correct

carburetor part number. An alternate method to find

the correct carburetor part number is to use the

manufacturing number stamped on the carburetor and

convert this number to a service part number. In the

carburetor section of the Master Parts Manual or

Microfiche Catalog, a cross reference chart will

convert a carburetor manufacturing number to a

Tecumseh Service part number.

AL TERNATE LOCATION FOR MANUFA CTURING NUMBER

89 4F5

Complete carburetor replacement may be

accomplished by a standard service carburetor. A

standard service carburetor is a basic carburetor that

may require the use of original carburetor parts or

additional new parts to adapt to the specification. An

MANUF ACTURING NUMBER

CARBURETOR DATE CODE

instruction sheet is provided with the new service

carburetor or see SERVICE in this chapter.

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

starting device is operated to start the engine,

downward piston travel creates 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. 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

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

idle.

CHOKE PLA TE

FLA T DOWN

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.

For the fuel to flow, the carburetor bowl must be either

vented externally or internally. Some internally

vented float style carburetors use a tygon tube and

a vent within the air intake. This tube must be present

for the carburetor to operate properly (diag. 3).

Air is bled into the main nozzle through the air bleed

located in the air horn. This mixes fuel and air prior

to the fuel leaving the main nozzle. Atomization occurs

as the fuel mixture contacts the fast moving air stream

and the mist flows into the intake of the engine.

FUEL PRIMERS

TYGON TUBE

INTERNAL VENT

EXTERNAL VENT

Primers may be mounted remotely or as an integral

part of the carburetor. The basic function of the primer

is to supply an air pressure charge to the carburetor

main well or carburetor bowl to displace fuel directly

into the carburetor venturi. This displaced fuel

provides a rich mixture necessary for engines to start

easily on the first or second attempt (diag. 4 & 5).

Primers must be vented either internally through a

passage in the carburetor air horn prior to the venturi

or externally through a hole in the primer bulb. The

vent allows atmospheric air to enter the fuel bowl

during operation and to fill the primer bulb after the

primer bulb is released.

IMPULSE FUEL PUMPS

Impulse fuel pumps may either be mounted externally

onto the carburetor fuel inlet or remotely mounted.

This pump is connected in the fuel line between the

fuel supply and the carburetor or directly to the fuel

inlet.

Impulse fuel pumps are operated by crankcase

impulses created by the up and down movement of

the piston. A hose called a pulse line connects the

fuel pump diaphragm chamber to the crankcase and

transmits the impulses to the pump diaphragm. The

impulses actuate the diaphragm and flap valves to lift

the fuel from the fuel tank to the carburetor (diag. 6).

A crankcase overfilled with engine oil can affect pump

operation.

PRIMER BULB

VENT

CRANKCASE PRESSURE

ATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGM FUEL FLOW

VALVE CLOSED

ATMOSPHERIC VENT

VALVE OPEN

FUEL SUPPLY

CRANKCASE SUCTION AND

FLOW DIRECTION ATMOSPHERIC PRESSURE ACTING ON DAMPING

DIAPHRAGM

PRIMER BULB

MAIN NOZZLE

MAIN JET

CARBURETOR FITTING

VALVE OPEN

DIAPHRAGM

FILTER

AIR BLEED

VALVE CLOSED

PULSE LINE TO CRANKCASE

SUCTION FUEL FLOW DIRECTION ATMOSPHERIC PRESSURE CAUSED FUEL FLOW

FLOAT STYLE CARBURETORS

A float is used to maintain the operating level of fuel

in the carburetor bowl. As the fuel is used by the

engine, the fuel level in the carburetor bowl drops and

the float moves downward. This allows the inlet needle

valve to move off the sealing seat. Fuel flows by gravity

or a pulse pump into the fuel bowl. As the fuel level in

the bowl again rises, it raises the float. This upward

float motion moves the inlet needle valve to the closed

position. When the needle contacts the seat, the fuel

flow is stopped. The tapered end of the inlet needle

varies the fuel flow rate and the fuel level in the

carburetor bowl remains constant (diag. 7). The float

height is set according to the service procedure.

THROTTLE SHUTTER

IDLE ADJUSTMENT

MAIN NOZZLE

IDLE AIR BLEED

MAIN ADJUSTMENT

MAIN AIR BLEED

CHOKE SHUTTER

INLET NEEDLE AND SEAT

FLOAT

CARBURETOR VISUAL IDENTIFICATION

Series1 Carburetors

Series 1 carburetors are used on some 4 - 7 model

overhead valve engines. This float style carburetor

has a smaller venturi than the Series 3 or 4 carburetor

and has no bosses on each side of the idle mixture

screw. The main and idle mixture may be fixed or

adjustable. A remote primer or choke may also be

used with this carburetor (diag. 8).

Series 3 & Series 4 Carburetors

Series 3 or 4 carburetors are generally used on 8

through 14 model 4-cycle engines. The quickest way

to identify these carburetors is by the presence of

bosses on each side of the idle mixture screw (diag.

9).

To determine whether the carburetor is a Series 3 or

Series 4, look at the throttle end of the carburetor.

Series 3 will have one throttle plate screw (diag. 10).

The Series 4 will have two throttle plate screws (diag.

11).

Series 6 Carburetors

Series 6 carburetors are used on 2 and 4-cycle

engines in the 3 to 6 model range. Series 6 uses a

simple fixed idle and fixed main fuel circuit. Series 6

carburetors are commonly used on rotary mower

applications. Series 6 are nonadjustable, with a

stepped primer bulb and a bowl prime system (diag.

12).

Series 7

Series 7 carburetors are totally nonadjustable. The

die cast carburetor body is similar in appearance

and slightly longer than the Walbro LMK body. The

choke shaft is made of a plastic material with an

internal slot to hold the choke shutter. The carburetor

base is flat to accept a Vector style bowl that is held

on with a wire bail. (diag. 13)

Series 8

Series 8 carburetors have both a fixed main and a

fixed idle circuit. These carburetors are totally

nonadjustable. This series of carburetor uses an

integral primer system like the Series 6. Distinguish

this carburetor from the Series 6 by the fixed idle jet

that appears as a screw just above the bowl on the

primer side. This fixed idle jet may also be capped.

(diag. 14)

CAPPED FIXED IDLE JET

CAP

Series 9

Series 9 carburetors are hybrid versions of the

Series 8. This carburetor uses a fixed idle jet and fixed

main fuel circuit. This carburetor is totally

nonadjustable. The bowl nut uses a ball plug on the

bottom to cover the center drilling. Also visible is a

plastic main fuel discharge nozzle in the venturi. The

Idle mixing well and jet will be visible but not machined

(diag. 15)

Series 10

This carburetor is for use on all season engine

applications. It is the equivalent of the series "8" with

the addition of a choke. It has a fixed main and idle

with a serviceable main nozzle and a primer assist,

with the added benefit of a choke for cold weather

starting.

MIXING WELL CAST BUT NOT MACHINED

IDLE JET CAST BUT NOT MACHINED

CHOKE PLATE

FLAT SIDE DOWN

Walbro Model LMK

OHV 15-17 models use this float-feed carburetor. The

carburetor is attached to the intake pipe using studs

that also fasten the air filter body. Walbro model and

manufacturing numbers are found on the throttle end

of the carburetor. This carburetor has a fixed,

nonadjustable main mixture jet.

Idle mixture screws were adjustable on early

production OHV15. This has since changed to a fixed

idle jet which may be capped for tamper resistance.

If no spring is visible, the jet is fixed. Servicing should

be done by a Authorized Tecumseh Dealer.

LOW IDLE MIXTURE SCREW MA Y BE ADJUSTABLE OR FIXED

TESTING

1. After repeated efforts to start the engine using the procedure listed in the operators manual fail, check

for spark by removing the high tension lead and removing the spark plug. Install a commercially available

spark tester and check for spark. If the spark is bright blue and consistent, proceed to step 2. If no or

irregular spark see Chapter 8 under "Testing".

2. Visually inspect the removed spark plug for a wet condition indicating the presence of gasoline in the

cylinder.

NOTE: Check plug for correct reach (diag.

17).

3. If the spark plug is dry, check for restrictions

in the fuel system before the carburetor. If the

spark plug is wet, continue with step # 7.

CHECK THE FUEL CAP FOR PROPER

VENTING. With a proper draining receptacle,

remove the fuel line clamp on the carburetor

fuel inlet and pull the fuel line off the fitting.

Examine the fuel flow with the fuel cap both

on and off the fuel tank.

CAUTION: DRAIN THE FUEL INTO AN

APPROVED CONTAINER OUTDOORS, AND AWAY FROM ANY OPEN FLAME OR COMBUSTION

SOURCE. BE SURE THE ENGINE IS COOL.

NOTE: Todays fuels can cause many problems in an engines performance, due to the fuels quality

and short shelf life. Always check fuel as a primary cause of engine performance.

STANDARD

PLUG

OHV

4. Remove the air filter, heater box, or air cleaner assembly if applicable to visually check that the choke

shutter completely closes or check to see if fuel comes out of the main nozzle during priming.

5. If the fuel flow from the tank is adequate and no fuel is evident during priming, the carburetor will need

to be removed for service. See Service in this chapter or consult the Carburetion Troubleshooting

chart to diagnose carburetor symptoms. Improper fuel flow indicates the fuel, fuel line, filter or tank

require cleaning or replacement.

6. Check the engine compression using a commercially available compression tester and follow the

testers recommended procedure. Low compression, a dry spark plug, adequate fuel flow, and a known

good functional carburetor indicates an internal engine problem exists. See Chapter 9 under

Troubleshooting.

7. A wet spark plug indicates fuel is being supplied by the carburetor. The engine may be flooded by

a restricted air filter, carbon shorted or defective spark plug, excessive choking or over priming,

improperly adjusted or defective carburetor. With the spark plug removed and a shop towel over

the spark plug hole, turn the engine over slowly 3 or 4 times to remove excess gasoline from the

engine cylinder.

CAUTION: KEEP ALL COMBUSTIVE SOURCES AWAY. AVOID THE SPRAY FROM THE SPARK

PLUG HOLE WHEN CRANKING THE ENGINE OVER.

8. Replace the air filter if restricted or oil soaked. Replace the spark plug if questionable. Install the spark

plug and high tension lead and try to start the engine.

9. If the engine floods and fails to start, the carburetor will require service. See the proceeding Carburetion

Troubleshooting chart for additional causes. If the carburetor is functioning properly the problem may

be ignition timing related. See Chapter 8 Ignition under Troubleshooting.

SERVICE

Carburetor Pre-sets and Adjustments

Before adjusting any mixture screws the necessary carburetor presets should be made. Check for the proper

governor adjustments as outlined in Chapter 4. Identify the correct carburetor model and manufacturer to find

locations of the high and low speed adjustment screws. Check the throttle control bracket for proper adjustment

allowing a full choke shutter position. See Chapter 4 under "Speed Controls and Linkage". Check to see if the

normal maintenance procedures have been performed (oil changed, fresh fuel, air filter replaced or clean).

Consult microfiche card #30 to find the correct R.P.M. settings for the engine. Start the engine and allow it to

warm to operating temperature. The carburetor can now be adjusted.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

Pre-sets and Adjustments (Tecumseh and

Walbro carburetors)

Turn both the main and idle mixture adjusting screws

in (clockwise) until finger tight if applicable.

NOTE: OVERTIGHTENING WILL DAMAGE THE

Engine Model Main Pre-set Idle Pre-set

All models with

float-type carburetors 1-1/2 turn 1 turn

Tecumseh Carburetors

TAPERED PORTION OF THE NEEDLE.

Now back the mixture screws out (counterclockwise)

to obtain the pre-set figure in the chart shown.

NOTE: SOME CARBURETORS HAVE FIXED IDLE

AND MAIN JETS. IDENTIFY THE SERIES OF

CARBURETOR USING THE VISUAL IDENTI-

FICATION IN THIS CHAPTER. IDLE MIXTURE

FIXED JETS APPEAR AS ADJUSTING SCREWS

WITHOUT TENSION SPRINGS AND ARE NOT

ADJUSTABLE.

All models with

diaphragm-type

carburetors 1 turn 1 turn

Walbro Carburetors

Carburetor Model

LMK Fixed 1 turn if

adjustable

or seated,

if fixed

Final Adjustments

Start the engine and allow it to warm up to normal operating temperature (3 - 5 minutes). Set the speed control

to the HIGH or FAST position, then turn the main mixture adjustment screw in (clockwise) slowly until the

engine begins to run erratic. Note the position of the screw. Now, turn the screw out (counterclockwise) until

the engine begins to run erratic. Turn the screw in (clockwise) midway between these two positions. This will

be the best setting.

Set the speed control to the IDLE or SLOW position. Adjust the idle mixture screw following the same procedure

used to adjust the main mixture adjustment screw.

Identify the location of both HIGH and LOW speed adjustments, then locate the recommended HIGH and

LOW R.P.M. setting according to microfiche card # 30 and adjust the engine speed accordingly.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

TECUMSEH CARBURETORS

DUAL SYSTEM / SERIES "6"

NON-ADJUSTABLE

PRIMER NO CHOKE

FIXED HIGH AND LOW SPEED

SERIES "7"

MIXTURE

SERIES "3" & "4"

IDLE MIXTURE SCREW

MAIN MIXTURE SCREW

WALBRO

CARBURETOR

SERIES "8"

SERIES "9"

SERIES "10"

WALBRO LMK

CAPPED FIXED IDLE JET

NON-ADJUSTABLE

(ADJUSTABLE MAIN FOR

EXPORT)

NON-ADJUSTABLE

If further adjustment is required, the main adjustment should be made under a load condition.

If the engine stops or hesitates while engaging the load (lean), turn the main mixture adjusting screw out

(counterclockwise) 1/8 turn at a time, testing each setting with the equipment under load, until this condition is

corrected. A few Tecumseh carburetors were built as air adjust idle system. If you have one, the adjustments

are reversed out for lean in for richer.

If the engine smokes excessively (rich), turn the main adjusting screw in (clockwise) 1/8 turn at a time, testing

each setting with the equipment under load, until this condition is corrected.

After the main mixture screw is set, move the speed control to the IDLE or SLOW position. If the engine does

not idle smoothly, turn the idle mixture screw 1/8 turn either in (clockwise) or out (counterclockwise) until

engine idles smoothly.

Recheck the high and low R.P.M. setting and adjust as necessary.

CARBURETOR DISASSEMBLY PROCEDURE

NOTE : CARBURETORS THAT ARE EMISSION COMPLIANT (MANUFACTURING NUMBERS 5000 OR

GREATER) WITH FIXED IDLE OR MAIN JETS ARE TO BE REMOVED BY DEALERS ONLY FOR INSPECTION

AND CLEANING.

1. Note or mark the high and low mixture adjusting screws to aid in reassembly (if applicable). Remove

the high speed mixture screw, bowl nut, and float bowl. Remove the idle mixture screw assembly. On

Series 7 carburetors, release the wire retainer that retains the bowl and remove the bowl assembly. If

a screwdriver or similar tool is used to release the retainer, carefully move the retainer to prevent

bending of the wire.

2. Series 8 carburetors have a tamper resistant cap, over the fixed idle jet. (diag. 21). The cap is removed

by piercing it with an ice pick or similar instrument, then remove the jet for service, always replace the

cap.

3. Note the position of the spring clip on the inlet needle and float. Remove the float hinge pin with a

needlenose pliers. Some carburetors use a float dampening spring to aid the inlet valve to maintain a

steady position in rough service applications. Note the position of the hooks before removing the float

hinge pin (diag. 25). On Series 7 carburetors, grasp the crossbrace on the float with a needlenose

pliers and pull straight out to release the float hinge pin.

4. Remove the float, clip, and inlet needle.

5. Remove the inlet needle seat using a wire or a paper clip with a 3/32" (2.38 mm) hook end (Tecumseh

carburetors only, Walbro model LMK uses a non-serviceable seat). Push the hook through the hole in

the center of the seat and pull out to remove it.

6. On Series 7 only, remove the main nozzle tube, "O" ring, and spring located in the center leg of the

carburetor bowl. Remove the bowl drain screw and gasket. Remove the spring, metering jet, and "O"

ring.

7. Note or mark the action of the choke and throttle shutters and the hook points of the choke or throttle

return spring or seal retainer springs located on the top of the choke or throttle shaft.

NOTE: MARK THE EDGES OF THE THROTTLE AND CHOKE SHUTTERS PRIOR TO DISASSEMBLY.

THE SHUTTERS HAVE BEVELED EDGES AND MUST BE INSTALLED IN THE ORIGINAL POSITION.

Remove the throttle shutter, throttle shaft, choke shutter, springs and choke shaft by removing the

screw or screws that attach the throttle or choke shutter to the shaft inside the air horn. To remove the

choke shaft assembly on Series 7 or Walbro LMK carburetors, grasp the choke shutter with a pliers

and pull it through the slot in the choke shaft. Slide the choke shaft out of the carburetor body.

LONG END OF CLIP

CHOKE END

CLIP OPEN END OF CLIP

THROTTLE END

3/32"

(2.38 mm)

8. 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 (diag. 28).

9. 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" (3.175 mm) 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 (diag. 29).

NOTE: DO NOT REMOVE ANY BALL OR CUP PLUGS (diag. 29).

10. Note the direction of the inlet fitting. If necessary the inlet fitting can be removed by pulling with a pliers

or vise, do not twist. The fitting must be replaced. Tap a 1/4-20 thread inside the metal shank, use

1/4"-20 bolt and nut inserted into a 1/4" (6.350 mm) flat washer and 1/2" (12.700 mm) nut, thread the

bolt into the shank, and thread the nut down to pull out the shank.

11. The Walbro LMK carburetor main fuel jet can be removed only if the jet is damaged or if a high altitude

jet is needed to be installed. To remove place the carburetor firmly in a soft jawed vice. Using a punch

the same size or slightly smaller than the jet, drive the jet through and into the center leg. Insert the

high altitude jet in the same hole. Using a punch slightly larger than the diameter of the new jet, tap it

into place flush with the outside of the center leg casting (diag. 31).

SMALL CHISEL

PRY OUT PLUG

DO NOT ALLOW CHISEL POINT TO STRIKE CARBURETOR BOD Y OR CHANNEL REDUCER

PIERCE PLUG WITH TIP

WELCH PLUG T O BE REMOVED

SMALL CHISEL

BRASS OR BALL PLUG

ABOUT 1/8" (3.175 mm) WIDE

BALL PLUG

Impulse Fuel Pump

The valve type impulse pump can be serviced using

the following procedure.

1. Remove the old filter on the back of the pump

body if applicable.

2. Note or mark the pump body alignment, remove

the four screws and disassemble the pump.

3. Remove the gaskets, diaphragms, old valves

and spring bearing from the spring.

4. Clean the body parts with solvent.

5. Install new valves with the face of the valve

facing the raised portion of the passage. After

installation, cut off the extended portion of the

valves.

DO NOT REMOVE PLUGS

IDLE FUEL PASSAGE REDUCTION ROD INSIDE

ATMOSPHERIC VENT

HIGH SPEED JET

WALBRO LMK SERIES

6. Install the diaphragms against the center portion

of the body with the gaskets against the outside

covers. The parts can only can be assembled

one way without damage.

7. Install the spring bearing on the new spring and

place into position.

8. Assemble the body sections, install the retaining

screws, and torque the screws to 12 - 16 inch

pounds (1.36 - 1.81 Nm).

9. Install new filter in pump cavity if applicable.

1 - Body, Impluse

2 - Body, Pump

3 - Cover, Pump

4 - Bearing, Spring

5 - *Valve, Check (2)

6 - *Gasket, Pump Cover

7 - *Diaphragm, Pump (2)

9 - Screw, 1-1/4" (4)

10 - *Spring, Pressure

11 - *Filter, Air

FLOAT ADJUSTING PROCEDURE

All Tecumseh carburetors with an adjustable float

require the correct float height to achieve the proper

operation and easy engine starts. To check the float

FLOAT SETTING

FLOAT

FLOAT HINGE AND AXLE

setting, hold the carburetor in an upside down position.

Remove the bowl nut, float bowl, and "O" ring. Place

an 11/64" (4.36mm) diameter drill bit across the top

11 / 64" (4.36 mm)

of the carburetor casting on the opposite side and

parallel to the float hinge pin. The float must just touch

the drill bit when the bit is flush with the edge of the

float. If the float is too high or too low, adjust the height

by bending the tab accordingly. If the required

adjustment is minor, the tab adjustment may be made

without removing the float and carefully inserting a

ADJUSTING T AB INLET NEEDLE

AND SEAT

small bladed screwdriver to bend the tab.

If float sticking occurs due to deposits, or when the fuel tank is filled for the first time, this condition can be

quickly corrected by loosening the carburetor bowl nut one full turn. Turn the bowl 1/4 inch in either direction,

then return the bowl to its original position and tighten the bowl nut.

THE TECUMSEH SERIES 7 AND THE WALBRO MODEL LMK CARBURETOR HAVE A FIXED AND

NONADJUSTABLE FLOAT HEIGHT.

Inspection

After careful disassembly of the carburetor and the removal of all non metallic parts, all metallic parts should

be cleaned with solvent, or commercial carburetor cleaner, no longer than 30 minutes. Wearing eye protection,

use compressed air and soft tag wire or monofilament fishing line to clean internal carburetor passages. To

perform a proper carburetor rebuild, the welch plugs must be removed to expose the drilled passages.

Throttle and Choke

Examine the throttle and choke shaft, and carburetor body at the bearing points and holes into which the

linkage is fastened, and replace if worn or damaged. Any excessive wear in these areas can cause dirt to

enter the engine and cause premature wear. If dust seals are present, check the seal condition and the correct

placement next to the carburetor body.

Idle and High Speed Mixture Adjusting Screw

Examine the idle mixture needle tip and tapered

surface for damage. The tip and tapered surface of

the needle must not show any wear or damage. If

either is worn or damaged, replace the adjusting

needle. Tension is maintained on the screw with a

RET AINER NUT

"O" RING

BRASS WASHER SPRING

coil spring. Replace the O ring seal if removed (diag.

34).

Examine the tapered surface of the high speed mixture

needle. If the tapered surface is damaged or shows

wear, replace the needle.

HIGH SPEED ADJUSTMENT SCREW

Fuel Bowl Retaining Nut

The bowl nut contains the passage through which fuel

is delivered to the high speed and idle fuel system of

the carburetor. If a problem occurs with the idle system

of the carburetor, examine the small fuel passage in

the annular groove in the bowl nut. This passage must

be clean for the proper transfer of fuel into the idle

metering system.

Bowl nuts that are used on adjustable main, float style

carburetors may use either one or two metering ports.

This difference relates to calibration changes of the

carburetor, depending on the application (diag. 35).

FUELMETERING PORT

ONE-HOLE TYPE

IDLE FUEL TRANSFER PASSAGE

TW0-HOLE TYPE

FUELINLET

NOTE: DO NOT INTERCHANGE BOWL NUTS.

The fuel inlet ports must be free of any debris to allow

proper fuel flow.

Fuel Bowl, Float, Needle and Seat

NOTE: To prevent damage to the float bowl on Series 7 carburetor, pull straight up with a needle nose pliers in

the pocket closest to the main fuel well (diag. 37).

The float bowl must be free of dirt and corrosion. Clean the bowl with solvent or carburetor cleaner (soak 30

minutes or less).

Examine the float for cracks or leaks. Check the float hinge bearing surfaces for wear, as well as the tab that

contacts the inlet needle. Replace any damaged or worn parts.

The needle and seat should be replaced if any fuel delivery problems are experienced (flooding or starvation).

Sealing problems with the inlet needle seat may not be visible and replacement is recommended. Only the

inlet needle is serviceable on the Walbro model LMK carburetor.

FLOAT HINGE PIN

NEEDLE & SEA T

SEA T RET AINING RING

BOWL RETAINER

CHOKE SHAFT

CHOKE DUST SEAL

CHOKE RETURN SPRING

CHOKE SHUTTER

FUEL FITTING INLET NEEDLE

FLOAT

SERIES 7

FLOAT

MAIN NOZZLE EMULSION

"O" RING

POSITIONED IN GROOVE

SPRING

IDLE RESTRICTION

BOWL

'O' RING

MAIN JET

MAIN JET SPRING

GASKET

BOWL DRAIN

THROTTLE SHAFT

THROTTLE DUST SEAL

THROTTLE RETURN SPRING

IDLE SPEED SCREW

WELCH PLUG

IDLE MIXTURE SCREW

TENSION SPRING

THROTTLE SHUTTER

SCREW

FLOAT SHAFT

"O" RING

THROTTLE SHUTTER

THROTTLE SHUTTER SCREW

PRIMER BULB/ RET AINER RING

PRIMER BULB FIL TER

A TMOSPHERIC VENT WELCH PLUG

FLOAT

SEA T

NEEDLE

SPRING CLIP

HINGE PIN

"O" RING

NOZZLE

"O" RING

POSITIONED IN GROOVE

BOWL

WASHER

JET/BOWL NUT

SERIES 8, 9 & 10

THROTTLE SHAFT & LEVER

THROTTLE RETURN SPRING

DUST SEAL WASHER DUST SEAL

FUEL FITTING

"O" RING

SEAT AND CLIP INLET NEEDLE

SPRING CLIP

FLOAT SHAFT

FLOAT BOWL

BOWL NUT WASHER

BOWL NUT

WALBRO LMK SERIES 6

39 40

FLOAT BOWL

BOWL NUT WASHER

HIGH SPEED BOWL NUT

ASSEMBLY PROCEDURE

Welch Plugs

To install a new welch plug after cleaning the

carburetor, secure the carburetor in a vise equipped

with protective jaws. Place the welch plug into the

receptacle with the raised portion up. With a punch

equal to the size of the plug hole, merely flatten the

plug. Do not dent or drive the center of the plug below

the top surface of the carburetor. After installation of

the welch plug, seal the outer diameter with fingernail

polish (diag. 41).

NEW WELCH PLUG

FLAT END PUNCH

SAME OR LARGER DIAMETER OF PLUG HOLE

Throttle Shaft and Plate

When reassembling Tecumseh or Walbro carburetors,

it is important that the lines, lettering, or numbers on

the throttle plate are facing out when in the closed

position. If the throttle plate has only one line, this

line should be positioned in the 3 oclock position on

Series 3, 4, and 7 carburetors, and at the 12 o'clock

position on Series 1, 6, 8, 9 carburetors. (diag. 42 &

43).

Test the operation of the throttle and return spring if

equipped. If binding occurs, correct by loosening the

screws and repositioning throttle plate.

Always use a new screw(s) when reinstalling the

throttle shutter to prevent the screws from loosening

and being drawn into the engine. New Tecumseh

screws are treated with dry-type adhesive to secure

them in place.

NOTE: NEVER REUSE OLD SCREWS.

On Walbro LMK and Series 7 carburetors, install the throttle return spring on the throttle shaft with the squared end up. Slide the foam dust seal over the spring. Insert the throttle lever assembly into the carburetor body with both tangs of the return spring on the left side of the center boss (viewed from throttle end) and the flat side of the shaft toward the carburetor mounting flange. Install the throttle shutter to the throttle shaft using notes or marks to place the shutter as originally found (Series 7 must have the line on the shutter at the 3 o'clock position) (diag. 44).

THROTTLE PLATE

THROTTLE LEVER

TWELVE

O'CLOCK

POSITION

THREE

O'CLOCK

POSITION

DUST SEALS

Always use new throttle shutter screws when reinstalling. Install the screws so they are slightly

loose. Apply light downward pressure on the throttle shaft and rotate it clockwise to seat the throttle shutter in the bore, then tighten the throttle shutter screws. Check for binding by rotating the throttle shaft. If necessary , adjust the throttle shutter by loosening and repositioning the shutter, then retighten the screws (diag. 45).

THROTTLE LEVER

THROTTLE PLATE

SERIES 7

WALBRO LMK SERIES

Choke Shaft and Plate

The choke plate is inserted into the air horn of the

carburetor in such a position that the flat surface (if

applicable) of the choke is down. Choke plates will

operate in either direction. Make sure it is assembled

properly for the engine. Test the operation of the choke

and return spring function if equipped (diag. 46).

Always use a new screw(s) when reinstalling the

choke shutter as the screws are treated with dry-type

adhesive to secure them in place.

NOTE: NEVER REUSE OLD SCREWS.

The choke shaft and plate must be in the closed

position prior to tightening the screws. Hard starting

may be due to insufficient choking action because of

a misaligned choke plate. Correct by readjusting the

choke plate to close completely. Note the cutout

position of choke shutter if applicable.

On Walbro LMK and Series 7 carburetors, install the

choke return spring on the choke shaft with the

squared end up and hooked into the notch in the plate.

Work the dust shield up around the spring and insert

the choke shaft into the carburetor body. Rotate the

shaft counterclockwise until the tang on the spring

rests against the left side of the center boss on the

carburetor body (viewed from choke end) . Rotate the

choke shaft approximately 1/4 turn counterclockwise

and insert the choke shutter into the slot in the choke

shaft. Make sure the tabs on the shutter lock the choke

shaft between them. Rotate the shaft and check for

binding, the choke must return to the open position

when released (diag. 47).

CHOKE PLA TE

PRESS IN P AR TIALLY THEN APPLY LOCTITE

FLA T DO WN

SOME INLET FITTINGS

STRAINER

SPRING HOOKUPS

Fuel Inlet Fitting

When installing the fitting, insert the tip into the

carburetor body. 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 (diag. 48).

High and Low Speed Adjusting Screw, Main

Nozzle

When reassembling, position the coil spring on the

adjusting screws, followed by the small brass washer

and the O ring seal. Turn the high speed adjustment

screw into the bowl nut and the low speed mixture

screw into the carburetor body (diag. 49).

Some carburetors may have a fixed main mixture or

both a fixed idle mixture and main mixture, and are

not adjustable.

On Series 7carburetors, place the main nozzle spring

into the main nozzle cavity. Apply oil to the main nozzle

"O" ring and push the main nozzle into the cavity

with the "O" ring end in first.

Next install the "O" ring in the main jet cavity. Place

the spring over the shoulder on the main jet and push

the jet into the cavity with the main jet toward the "O"

ring. Place a new gasket on the drain screw and

tighten in position (diag. 50).

On Walbro LMK carburetors, the main jet can be

replaced by pressing it into the center leg of the

carburetor until flush. (diag. 31 page 15).

NOTE: FOR HIGH ALTITUDE JETTING, CONSULT

BULLETIN 110.

RET AINER NUT

FLOAT HINGE PIN

NEEDLE & SEA T

SEAT RETAINING RING

"O" RING

BRASS WASHER

SPRING

HIGH SPEED ADJUSTMENT SCREW

FLOAT

MAIN NOZZLE EMULSION

"O" RING POSITIONED IN

GROOVE

SPRING

IDLE RESTRICTION

BOWL

"O" RING

MAIN JET

MAIN JET SPRING

GASKET

BOWL RETAINER

BOWL DRAIN

Inlet Needle and Seat

Make sure the seat cavity is clean. Moisten the seat

with oil and insert the seat with the grooved side down

and away from the inlet needle. Press the seat into

the cavity using a 5/32" (3.969 mm) flat punch, making

sure it is firmly seated (diag. 51). On Series "7"

carburetors, install the seat retainer into the cavity

and push it down using the flat punch until it contacts

the seat.

PUSH IN UNTIL SEAT RESTS ON BOD Y SHOULDER

IF Y OUR CARBURET OR HAS A STEEL SEAT RETAINING RING RE-INTSALL AFTER SEA T INSTALLATION

INLET NEEDLE SEATS AT THIS POINT

5/32" (3.969 mm) FLA T PUNCH

SEAT

INSERT THIS F ACE FIRST

The inlet needle hooks onto the float tab by means of

a spring clip. To prevent binding, the long, straight

end of the clip should face the choke or air filter end

of the carburetor as shown (diag. 52).

Float Installation

On Series 7 carburetors, slide the hinge pin into the

hinge on the float. Position the needle into the fuel

inlet and snap the float pin into the tabs on the float

bowl. Float height is not adjustable.

On Series 7 carburetors and the Walbro LMK, reinstall

the inlet needle on to the float and place it into the

carburetor (diag. 53).

1. When rebuilding a carburetor with a clip on

the needle, position carburetor float side up

for assembly.

2. Place the inlet needle and spring clip onto

the float as shown. The long end of the spring

clip must point towards the choke end of the

carburetor. This will ensure that the inlet

needle will move up and down in a straight

line (diag. 53).

3. To set the proper float height on carburetors

except Series 7 and Walbro LMK, see

adjusting procedure.

LONG END OF CLIP

Points toward chok e end

CHOKE END

SERIES 7 WALBRO / LMK

LONG END OF CLIP Points toward choke end

CLIP OPEN END OF CLIP

THROTTLE END

CLIP

OPEN END OF CLIP

4. Some Tecumseh float style carburetors have

a damper spring which is installed as shown

in diag. 55.

POINTS TOW ARD THE CHOKE END

Fuel Bowl And Bowl Nut

Whenever a carburetor bowl is removed for service,

the fuel bowl O ring (or gasket on Series "7") and

the bowl nut washer must be replaced. For easier

installation, lubricate the O ring with a small amount

oil.

Installing the Float Bowl

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.

Impulse Fuel Pump

The diaphragms must be installed against the center

body with the gaskets against the outside covers. The

parts are designed so they cannot be misassembled

without damage (diag. 57).

To test the unit, assemble the carburetor to the engine,

leaving the fuel line from the pump off. Use a different

fuel tank remotely placed above the carburetor to

provide gravity fuel flow to the carburetor inlet to run

the engine while testing the pump. Make sure fuel is

available in both fuel tanks and the original fuel tank's

fuel line is connected to the fuel pump inlet. Place the

pump outlet line in a proper draining receptacle. With

the pulse line connected from the engine crankcase

to the pump and the engine running, a definite fuel

flow should result at the pump outlet.

DETENT

CRANKCASE PRESSURE

ATMOSPHERIC PRESSURE ACTING

ON DAMPING DIAPHRAGM FUEL FLOW

VALVE CLOSED

ATMOSPHERIC VENT

VALVE OPEN

FUEL SUPPLY

CRANKCASE SUCTION AND

FLOW DIRECTION ATMOSPHERIC PRESSURE ACTING ON DAMPING

DIAPHRAGM

CARBURETOR FITTING

VALVE OPEN

DIAPHRAGM

FILTER

AIR BLEED

VALVE CLOSED

PULSE LINE TO CRANKCASE

SUCTION FUEL FLOW DIRECTION

ATMOSPHERIC PRESSURE CAUSED FUEL FLOW

If the flow is erratic or intermittent, the pump needs

repair or replacement.

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' (19.05 mm)

deep well socket (diag. 58).

Final Checks

Before reinstalling a newly overhauled carburetor, pre-

set the main mixture adjustment screw, the idle

mixture adjustment screw and the idle speed

adjustment screw. See Pre-sets and Adjustments

in this chapter.

CHAPTER 4 GOVERNORS AND LINKAGE

GENERAL INFORMATION

Tecumseh 4 cycle engines are equipped with mechanical type governors. The governors function is to maintain

a R.P.M. setting when engine loads are added or taken away. Mechanical type governors are driven off the

engines camshaft gear. The governor follower arm rests on the center of the governor spool on center force

governors, and off to one side on other governor systems. Changes in engine R.P.M. cause the governor lever

to move the solid link that is connected from the governor lever to the throttle in the carburetor. The throttle is

opened when the engine R.P.M. drops and is closed as an engine load is removed.

This chapter includes governor assembly linkage illustrations to aid in governor or speed control assembly.

OPERATION

As the speed of an engine increases, the governor

weights on the governor gear move outward by

centrifugal force. The shape of the governor weights

force the governor spool to lift. The governor rod

maintains contact with the governor spool due to the

governor spring tension. The governor rod rotates

causing the attached outer governor lever to push the

solid link and close the throttle opening. When the

engine speed decreases, the lower centrifugal force

allows the governor weights to be pulled in by the

governor spring. The governor rod rotates and the

solid link moves the throttle to a more open position

(diag. 1).

THROTTLE

GOVERNOR GEAR

SPRING

GOVERNOR SHAFT

WEIGHTS

GOVERNOR SPOOL

TROUBLESHOOTING

Engine operation problems where the governor is suspected to be the cause may actually be the result of

other engine system failures. Hunting (engine R.P.M. surging up and down) indicates that the engine is incapable

of maintaining a constant R.P.M. with or without an engine load. Engine overspeeding must be corrected

immediately before serious engine damage occurs. Use the applicable following procedure to diagnose a

suspected governor failure.

ENGINE OVERSPEEDING

1. If the engine runs wide open (faster than normal), shut the engine off or slow it down immediately.

2. Check the condition of the external governor shaft, linkage, governor spring, and speed control assembly

for breakage or binding. Correct or replace binding or damaged parts.

3. Follow the governor adjustment procedure and reset the governor - see "Service" in this chapter.

4. Run the engine. Be ready to shut the engine off if an overspeed problem still exists. If the problem

persists, the engine will require disassembly to inspect the governor gear assembly for damage, binding,

or wear.

5. See Chapter 9 under "Disassembly Procedure" to disassemble the engine.

6. Remove the governor gear assembly. Repair or replace as necessary.

ENGINE SURGING

1. Try to stabilize the engine R.P.M. by holding in one position the solid link between the governor arm

and the carburetor throttle, using a pliers or fingers.

2. If the engine R.P.M. stabilizes, the governor or governor adjustment should be checked. See "Service"

governor adjustment procedure in this chapter. If the engine R.P.M. does not stabilize, the engine will

require additional checks see Chapter 9 under "Troubleshooting".

3. If the problem persists after the governor adjustment, check the engine R.P.M. found on microfiche

card # 30. The R.P.M. settings are critical. If the R.P.M. setting for high and low speed are within

specification and a slight surge is experienced, increasing the engine idle R.P.M. setting slightly may

eliminate this condition.

4. Check the governor shaft or linkages for binding, wear, or improper hookup. Check the governor

spring for adequate tension or damaged condition. Repair or replace as necessary.

SERVICE

GOVERNOR ADJUSTMENT

With the engine stopped, loosen the screw holding the governor lever to the governor shaft clamp. Push the

governor lever to move the carburetor throttle plate to the wide open position. Rotate the governor clamp

counterclockwise on all overhead valve engines covered in this manual. Hold the lever and clamp in this

position while tightening the screw (diag. 2).

PUSH LEVER TO WIDE OPEN THROTTLE

GOVERNOR CLAMP SCREW

TURN CLIP COUNTERCLOCKWISE ON ALL VERTICAL SHAFT ENGINES EXCEPT VLV & VLXL. CLOCKWISE ON ALL HORIZONTAL SHAFT ENGINES EXCEPT OHH,OHSK 50,55 & OHM, OHSK 110,120.

THROTTLE LINK

GOVERNOR

LEVER

GOVERNOR

ROD

GOVERNOR

CLAMP

SCREW

YOU MUST USE THIS

LINK POSITION

ROTATE LEVER

& ROD

COUNTER-

CLOCKWISE

OHH SERIES - NEW STYLE

THROTTLE PLATE

THROTTLE OPEN

(PUSH COUNTER-

CLOCKWISE)

THROTTLE

PLATE

(TOP VIEW)

THROTTLE OPEN (PUSH COUNTERCLOCKWISE)

STANDARD LOCATION

GOVERNOR LEVER

GOVERNOR SCREW

GOVERNOR ROD

GOVERNOR CLAMP

ROTATE CLAMP COUNTERCLOCKWISE

OHH SERIES - OLD STYLE

GOVERNOR GEAR AND SHAFT SERVICE

After the cylinder cover is removed from the engine, the governor spool, gear, or governor shaft can be

removed. On some governor assemblies, the retaining ring must be removed to allow the spool or gear to

slide off the shaft. Other governor shafts use an upset to hold the governor spool on. If the gear requires

replacement, the governor shaft will have to be removed.

Governor Gear or Shaft Replacement,

Upset Style Governor Shaft

1. Grip the original spool in a vise and use a

twisting and pulling motion on the flange until

the spool is free.

2. Clamp the shaft in a vise and pound gently

on the flange with a wooden or plastic mallet

to remove the shaft (diag. 4).

NOTE: DO NOT TWIST THE SHAFT WHEN

REMOVING. THE SHAFT BOSS MAY

BECOME ENLARGED AND THE PRESS FIT

WILL NOT SECURE THE NEW GOVERNOR

SHAFT.

3. To install a new shaft, first assemble the gear

and washer on the shaft. Start the shaft into

the hole with a few taps from a soft faced

hammer.

4. Place the flange in a press with a solid piece

supporting the area below the shaft boss.

Press the shaft in until a part # 670297

(.0125" / .3175 mm) shim just becomes snug

(.010" - .020" / .254-.508 mm clearance)

(diag. 5).

GEAR

SHIM

WASHER

SHAFT BOSS

670297 (modified)

Governor Shaft Replacement, Retaining Ring Style

1. Remove the retaining ring, spool, gear assembly, and washer(s).

2. Clamp the shaft in a vise and pound gently on the flange with a wooden or plastic mallet to remove the

shaft.

NOTE: DO NOT TWIST THE GOVERNOR SHAFT WHEN REMOVING. THE SHAFT BOSS MAY

BECOME ENLARGED AND THE PRESS FIT WILL NOT SECURE THE NEW GOVERNOR SHAFT.

3. Start the new shaft into the shaft boss by tapping with a soft faced hammer.

4. Refer to the chart at right for the proper shaft exposed length from the mounting surface. Add a drop

of red Loctite 271 and press the governor shaft to the proper depth using a press or a vise. Wipe the

extra Loctite off after installation.

5. Reassemble the washer (s), governor gear, and spool followed by the retaining ring.

ENGINE MODEL EXPOSED SHAFT LENGTH

OHH/OHSK50-70 1.319" - 1.334"

OVRM (33.502 - 33.883 mm)

OHM 1.085" - 1.100"

OHSK80-130 (27.559 - 27.940 mm)

OVM

OVXL 1.350" - 1.365"

OHV (34.290-34.671 mm)

GEAR ASSY.

OVRM TYPE I

RETAINING RING

SPOOL

RETAINING RING

(GOV.)

WASHER

SHAFT

SERVICED AS ASSEMBLY

SPOOL

UPSET

SHAFT

GEAR ASSY.

(GOV.)

WASHER

OVRM TYPE II

RETAINING RING

SPOOL

WASHER

RETAINING RING

GEAR ASSY.

(GOV.)

WASHER

SPACER

SHAFT

OHH / OHSK50-70

MEDIUM FRAME

SPOOL

SHAFT

GEAR ASSY. (GOV.)

WASHER

OVM / OHV / OHM

SPOOL WASHER

RETAINING RING

GEAR ASSY. (GOV.)

WASHER

SPACER NOTE; SPACER MAY BE PART OF THE GEAR ASSEMBLY.

SHAFT

OHSK80-130

Speed Controls And Linkage

Many different types of speed controls and linkage are used for O.E.M. applications. Linkage attachment

points are best recorded or marked prior to disassembly. This assures the correct placement during reassembly.

The solid link is always connected from the outermost hole in the governor lever to the throttle in the carburetor.

The governor spring is connected between the speed control lever and the governor lever. Vertical shaft

engines may use an adjustable intake pipe mounted speed control bracket located above the carburetor, or a

vertical or horizontal control mounted on the side of the engine. The ignition ground out terminal, idle R.P.M.

and high speed R.P.M. adjustment screws may be located on the speed control bracket.

The adjustable speed control bracket which is

mounted on the intake pipe must be aligned properly

when installing. To align the control bracket, use the

following steps.

1. Loosen the two screws on the top of the panel.

2. Move the control lever to full wide open throttle

position and install a wire or aligning pin through

the hole in the top of the panel, the hole in the

choke actuating lever, and the hole in the choke

(diag. 12).

3. With the components aligned, tighten the two

screws on the control panel.

The following pages show common linkage hookup

arrangements. Whenever the carburetor or the

governor linkage is removed or replaced, the engine

R.P.M.'s should also be checked. Use microfiche card

#30 or contact a local Tecumseh dealer for the correct

R.P.M. settings for the engine model and specification.

NOTE: RPM SETTINGS CAN ALSO BE FOUND ON

THE COMPUTERIZED PARTS LOOK UP SYSTEMS.

HIGH SPEED STOP

OHH REMOTE SPEED CONTROL

The engine and equipment control must be adjusted

to allow the engine control lever to touch the high

speed stop when the equipment control is set in the

"highspeed" or "fast" position. Loosen the bowden wire

clamp, place the equipment control to the "fast"

position, move the engine control lever to contact the

high speed stop, and hold the lever in this position

while tightening the bowden wire clamp.

OHH GOVERNED IDLE SPEED CONTROL

This control is adjusted by bending the tabs on the control bracket to achieve the correct idle speed and high

speed. When the engine is running, the governor controls both the idle and the high engine speed. In order for

the governor to respond properly to a crankshaft load at engine idle, the idle speed screw on the top of the

carburetor must be set 600 RPM lower than the governed idle speed. Use the following procedure to set the

engine speeds (diag. 14 & 16).

1. Check to find the correct engine speeds found on microfiche card # 30 or using the Computer Parts Look-

up System.

2. Start and allow the engine to run ( 3-5 minutes) before beginning adjustments. Place the control knob in

the lowest engine speed position. Use a Vibra-Tach or other tachometer to set the non-governed idle

speed (600 RPM lower than the governed idle speed) by pushing the bottom of the governor lever away

from the control bracket so the throttle lever contacts the idle speed screw and hold the lever in this

position. Turn the idle speed screw clockwise to increase or counterclockwise to decrease engine idle

speed.

3. Allow the governor to control the throttle. Use a Vibra-Tach or other tachometer and bend the tab as

shown to achieve the specified governed idle speed.

4. Slide the control knob to the high speed position and bend the tab as shown to achieve the specified

governed high engine speed.

NOTE: Early production OHH engines did not have governed idle, set only the idle crack screw and high

speed governor stop.

WINTER APPLICATION CONTROL

GOVERNED IDLE LINK AND ADJUSTMENT

HIGH SPEED ADJUSTMENT

BEND T O ADJUST SPEED DECREASE INCREASE

OHH REMOTE & MANUAL

GOVERNOR SPRING

OHH RV CONTR OL

GOVERNED IDLE LINK

T-10THROTTLE CRACK SCREW

GOVERNED HIGH SPEED ADJUST

OHH FIXED SPEED

THROTTLE CRACK SCREW

CORRECT BUSHING INSTALLATION DEEP SIDE HERE

HIGH SPEED PIN POSITION

INCREASE DECREASE

GOVERNED IDLE TAB

LOW SPEED TAB

HIGH SPEED ADJUST

T-10

BEND

OH / OHSK CONTROL

HIGH SPEED TAB

GOVERNED HIGH SPEED ADJUST

1716

NOTE: ON REMOTE CONTROL THIS WILL NOT BE PRESENT

GOVERNED IDLE SCREW

OHSK / OHM CONTROL

HIGH SPEED ADJUST

LOW SPEED ADJUST

OVRM OVRM

DECREASE

INCREASE

OVRM SNAP IN CONTROL

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