Tecumseh Quick Reference Service Information and Troubleshooting Guide

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Tecumseh

Quick Reference

Service Information

Covers Engine and Transmission Product

Form No.695933 R 7/00

Introduction

This booklet contains the quick reference and basic trouble- shooting information previously found on Tecumseh wall charts and in the Technician's Handbooks.

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

Technician's Note:

Tecumseh engines are manufactured to meet EPA and CARB standards. As a technician, it is unlawful to re-calibrate or replace a fuel nozzle or jet (bowl nut) with a part from any other carburetor that was not originally designed for that engine. All speed adjust- ments must remain within the limits that are specified for each engine and are not to exceed the maximum. This can only be deviated from if specifically approved by Tecumseh Products, EPA and CARB.

1

Note: Torque specifications listed should not be confused with the torque value observed on engines which have been run.

The Torque specifications take relaxation into account so sufficient clamping force exists after an engine has reached operating temperature.

Torques listed are intended to cover highly critical areas. More extensive torques are found in the respective repair manual.

Torque Specifications

TWO-CYCLE ENGINE SERIES

840 - 850 TWO-CYCLE ENGINE SERIES

Location

Inch lbs. Torque

Nm

Engine Designation

Crankcase to Cylinder	120-204	13.5-23
Flywheel Nut	360-420	41-47.5
Adapter Plate to Cylinder	160-220	18-25

TVS		TVXL		HSK		HXL
•		•		•		•
•		•		•		•
•		•

TC TWO-CYCLE ENGINE SERIES

Location	Inch lbs. Torque	Nm	Engine Designation
				TC200	TC300	TCH200/ 300
Cylinder to Crankcase	80-95	9-11		•	•	•
Crankcase Cover to Crankcase	70-100	8-11		•	•	•
Flywheel Nut	190-250	21.5-28.5		•	•	•

TWO-CYCLE ENGINE SERIES (AV520/600, TVS600, AH520, AH/HSK600)

Location

Inch lbs. Torque Nm

Engine Designation

Connecting Rod	40-50	4.5-5.5
Housing Base to Cylinder	80-120	9-13.5
Cylinder Head to Cylinder	100-140	11-16
Flywheel Nut AV Industrial (Point Ignition)	216-300	24.5-34
(670 Series AV 520 and All AV 600)
Flywheel Nut (C.D. Ignition)	264-324	30-36.5

AV520/600		TVS600		AH/HSK600		AH520
•		•		•		•
•		•		•		•
•		•		•		•
•						•
•		•		•		•

2

Two Cycle Troubleshooting

As an aid in troubleshooting any piece of equipment, interview the customer, and review conditions and symptoms of the problem. Examine exterior for clues: leaks, excessive dirt, damaged or new parts.

FUEL SYSTEM

Engine Will

Not Start

Check if spark

plug is wet or dry

Wet

Dry

	Defective		Review with customer
	spark plug		priming or choking
			procedure
			(3-5 primes, if
	Restricted		equipped, waiting 2
			seconds between
	air filter
			each prime)
			Carburetion problem*
	Improper fuel mix
	or stale fuel		(bad bowl gasket)
			Check fuel supply
	Exhaust ports
			and fuel cap vent
	plugged
	Carburetion		Restriction in
	problems due to		fuel system (filter,
	flooding, over		screen)
	priming, etc.*
			Poor
	Ignition System		compression
			Damaged reed,		port
	Crankcase seals
			plugs, seals or
	or gaskets leaking		gaskets
	NOTE: Refer to Technician's Handbook for a more
	detailed list of remedies.
	*Carburetor Troubleshooting use Technician's
	Handbook or Carburetor Troubleshooting Booklet,
	Form No. 695907. Video No. 695015.
		(CONTINUED ON NEXT PAGE)			3

Two Cycle Troubleshooting - continued

IGNITION SYSTEM

Engine Will

Not Start

Check for spark

Spark

No Spark

Check flywheel for

correct key, damaged

key or key adaptor

Set proper air gap on

external coil

Set proper point gap, check condensor and timing (if equipped)

Test coil for

intermittent or weak

spark

Check electric starter

if applicable

Replace spark plug

Isolate engine from all equipment (disconnect wiring harness), repeat test

	Spark	No Spark
Equipment problem,		Engine problem,
check switches, wiring		check for shorts or
and equipment		grounds in wiring
controls
Parasitic load too high		Test ignition module

NOTE: Refer to Technician's Handbook for a more detailed list of remedies.

4

Note: Torque specifications listed should not be confused with the torque value observed on engines which have been run.

The Torque specifications take relaxation into account so sufficient clamping force exists after an engine has reached operating temperature.

Torques listed are intended to cover highly critical areas. More extensive torques are found in the respective repair manual.

Torque Specifications

FOUR-CYCLE LIGHT FRAME ENGINE SERIES

(TVS, TNT, ECV, LAV, LEV, H, HS, OHH, OVRM and VLV)

Location	Inch lbs. Torque	Nm
			TVS
Rocker Arm Stud Lock Nut	100-140	11-16
Connecting Rod	95-110	11-12.5	•
Cylinder Head	160-210	18-24	•
Cylinder Head	220-240	25-27
Cylinder Head	180-220	20.5-25
Mounting Flange or Cylinder Cover	100-130	11-14.5	•
Flywheel Nut (Cast Iron)	500-600	42-50	•
Flywheel Nut (Aluminum)	400-500	45-56.5	•

FOUR-CYCLE MEDIUM FRAME ENGINE SERIES

(TVM, TVXL, H, V, HM, OVM, OVXL, OHM, OHSK and OHV)

Engine Designation

TNT

ECV

LAV

H/HSK

HS/HSSK

OVRM

VLV

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

LEV

•

•

•

•

OHH •

•

•

•

•

•

Location	Inch lbs.	Nm
	Torque
			TVM125, 140
Connecting Rod	160-180	18-20.5	•
Connecting Rod	200-220	22.5-25
Connecting Rod	200-240	22.5-27
Cylinder Head Bolts	220-240	25-27
Cylinder Head Bolts	180-240	20.5-27
Cylinder Head Bolts	160-210	18-24	•
Rocker Adj. Lock Screw	65-80	7-9
Rocker Arm Stud Lock Nut	110-130	12.5-14.5
Rocker Arm Hex Jam Nut	15-20	2
Rocker Arm Studs	170-210	19-24
Rocker Arm Box to Head	75-130	8.5-14.5
Rocker Box Cover	15-20	2
Rocker Box Cover (Four Screw)	40-65	4.5-7
Mounting Flange or Cylinder Cover 100-130		11-14.5	•
Mounting Flange or Cylinder Cover 110-140		12.5-16
Flywheel Nut	400-550	45-62	•
Flywheel Nut (External Ignition)	600-800	68-90

H50-60

•

•

•

•

V70

•

•

•

•

H70

•

•

•

•

Engine Designation

TVM & TVXL 170-195-220		HM/HMSK70-100		OVM/OVXL, OHV120-125		OHSK80-130 OHM120		OHV11-13,OHV110- 135, 206 Series
•		•		•		•
				•		•		•
•		•
				•		•		•
				•		•
				•		•
				•		•
						•		•
•		•		•		•		•
•		•		•		•		•

OHV135-145 203 Series OHV15-17.5 204 Series

•

•

•

•

•

•

•

5

Torque Specifications - continued

FOUR-CYCLE LARGE FRAME ENGINE SERIES (CAST IRON BLOCK HH, VH and OH)

Location	Inch lbs.	Nm
	Torque
Connecting Rod	86-110	10-12.5
Cylinder Head	180-240	20.5-27
Mounting Flange & Cylinder Cover	100-130	11-14.5
Rocker Arm Shaft to Box	180-220	20.5-25
Rocker Arm Box to Cylinder Head	80-90	9-10
FlywheelNut	600-660	68-74.5

FOUR-CYCLE HEAVY FRAME ENGINE SERIES (V-TWIN)

Location	Inch lbs. Nm
	Torque

Connecting Rod	200-220 22.5-25
Cylinder Head Bolts	220-240 25-27
Rocker Arm Jam Nut	110-130	12.5-14.5
Rocker Arm Cover Mounting Screw	52	6
Mounting Flange/Cylinder Cover	240-260	27-29
FlywheelNut	600-800	68-90

Engine Designation

HH	VH	OH
•	•	•
•	•	•
•	•	•
		•
		•
•	•	•

Engine Designation

TVT •

•

•

•

•

•

6

Four Cycle Troubleshooting

As an aid in troubleshooting any piece of equipment, interview the customer, and review conditions and symptoms of problem. Examine exterior for clues: leaks, excessive dirt, damaged or new parts.

FUEL SYSTEM

Engine Will

Not Start

Check if spark plug is

wet or dry

Wet

Dry

Defective spark plug

Restricted air filter

Improper or

stale fuel

Carburetion problems due to flooding, over priming, etc.*

Ignition system

Review with the customer proper priming procedure

(3-5 primes, waiting 2 seconds between each prime)

If equipped with a

choke, check for full travel. Check throttle cable and control for proper adjustment.

Check fuel supply and

fuel cap vent

Restriction in fuel

system (filter)

Carburetion problem*

(bad bowl gasket)

Poor

compression

NOTE: Refer to Technician's Handbook for a more detailed list of remedies.

*Carburetor Troubleshooting, use Technician's Handbook or Carburetor Troubleshooting Booklet, Form No. 695907. Video No. 695015.

7

Four Cycle Troubleshooting - continued

IGNITION SYSTEM

Engine Will

Not Start

Check for

spark

Spark

No Spark

Check flywheel for
					Replace spark plug
correct key, damaged
or sheared key
				Isolate engine from all
Set proper air gap on				equipment (disconnect
external coil				wiring harness), repeat
						test
			Spark				No Spark
Set proper point gap,
check condensor and
timing		Equipment problem,					Engine problem,
		check switches,
							check for shorts or
		wiring and
Test coil for							grounds in wiring
		equipment controls
intermittent or weak
spark
		Parasitic load too					Test ignition
		high					module

NOTE: Refer to Technician's Handbook for a more detailed list of remedies.

8

Tecumseh 2 Cycle Diaphragm Adjustments

NOTE: For meeting emission requirements, some carburetors have fixed-main or idle jets. The absence of the adjustment screw indicates fixed jets and no adjustment is necessary.

Diaphragm-Dual Adjustment.

Turn mixture adjusting screws in finger tight to the closed position, then one (1) turn out from closed position. This setting is approximate. This will allow the engine to be started so the carburetor can be fine tuned.

Start the engine and let it warm up for approximately 3-5 minutes. Do not adjust the carburetor when the engine is cold.

IDLE MIXTURE

SCREW

MAIN MIXTURE SCREW

NOTE: If no tension spring is present, it may be a fixed jet.

1

Set the throttle control to idle. If it is a fixed speed type, manually hold the throttle against the idle speed adjustment screw.

The throttle lever must be held against the crack screw for low speed adjustments or all adjustments will be incorrect and cause poor performance and unsatisfactory operation.

With the engine idling and throttle lever against the idle speed regulating screw, turn the low speed adjustment screw slowly clockwise from the NORMAL setting until the engine falters. Remember this location. Turn the screw counterclockwise until engine just starts to sputter or drops in R.P.M.. Remember this location. Turn the screw clockwise until it is halfway between your first position where the engine faltered and your last position where the engine started to sputter. This will be the optimum low speed setting on your carburetor.

Next run the engine at governed speed. The high speed adjustments are made basically the same as the low speed adjustments, with the exception of the settings being made 1/8 of a turn at a time, from the NORMAL settings. NOTE: It may be necessary to re-check the idle mixture adjustment after performing the high speed adjustment.

Diaphragm-Single Adjustment.

Turn the mixture adjustment screw finger tight to the closed position, then one (1) turn out from the closed position. This setting is approximate and will allow the engine to be started so the carburetor can be fine- tuned.

Start the engine and let it warm up for approximately 3-5 minutes. Do not adjust the carburetor when the engine is cold.

Set the throttle control to idle. If it is a fixed speed type, manually hold the throttle against the idle speed adjustment screw.

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 to make mixture adjustments. Turn the mixture screw slowly clockwise from the NORMAL setting until the engine falters. Remember this location. Turn the screw counterclockwise until the engine just starts to sputter or drops in R.P.M. Remember this location. Turn the screw clockwise until it is halfway between your first position where the engine faltered and your last position where the engine started to sputter. This will be the optimum setting on your carburetor.

9

TC Series Governor Adjustment

Three different styles of governor systems are used on TC engines. Use the following illustrations (diags. 2 and 3) to identify the governor system used and the following procedure to adjust the governed engine speed.

1.Allow the engine to run for at least 5 minutes to reach operating temperature. Make sure the air filter (if equipped) is clean and the choke is in the off position.

2.Using a Vibratach (part# 670156) or other tachometer, determine the engine's R.P.M. at idle and wide open throttle. Refer to Microfiche card 30, or a computer parts look-up program to obtain the recommended engine speeds.

3.Using the applicable illustration, either bend the speed adjusting lever toward the spark plug end of the engine to decrease high speed R.P.M., or bend the lever in the opposite direction to increase R.P.M. On TC Type II engines, turn the speed adjusting screw out to increase or in to decrease engine high speed R.P.M. If the speed adjustment screw is turned out to increase the engine R.P.M., the speed control lever must be moved to allow the speed control plunger to contact the speed adjustment screw.

4.The low speed is set by moving the throttle control to the lowest speed position and adjusting the low speed adjustment screw on the carburetor.

HOOK SPRING ON NOTCH

TYPE I (style 2)

HOOK SPRING ON NOTCH

TYPE I (style 1)

SPEED

ADJUSTING

LEVER

BENDTO INCREASE SPEED BEND TO DECREASE SPEED

SPEED

ADJUSTING

LEVER

2

1.AIR VANE

2.BACKLASH SPRING

3.GOVERNOR LINK

4.GOVERNOR SPRING

5.MOUNTING SCREW

6.SPEED ADJUSTMENT SCREW

7.SPEED CONTROL BODY

8.SPEED CONTROL LEVER

9.SPEED CONTROL PLUNGER

Spring Color	Spring Position
Orange or Green	1
Pink, Red, or Black	2

1

5

TYPE II:

SPRING	HOOK
POSITION 1	SPRING ON
1	NOTCH
	POSITION 2

8

4

(style 3)

4

9

HIGH SPEED

GOVERNOR

ADJUSTMENT

2

3

SPRING

7

OUT TO INCREASE 6 IN TO DECREASE

INSERT THROTTLE LINK AND SPRING HERE

3

10

Walbro (WTA, WT) and Tillotson (HU) Diaphragm Adjustment

Carburetor Pre-Set and Adjustment

Both the Walbro and the Tillotson carburetors used on TC engines have non-adjustable main mixture jets. Only the idle mixture is adjustable by turning the idle mixture screw. Use the following procedure to pre-set the idle mixture screw. Turn the idle mixture screw (clockwise) finger tight to the closed position, then turn the screw counterclockwise to obtain the proper preset (diag. 4).

Walbro Model WTA, WT 1 - 1-1/8 turns Tillotson Model HU 1-1/4 - 1-3/8 turns

Final Idle Mixture Adjustment

Starttheengineandallowittoreachnormaloperating temperature (after 3-5 minutes). As the speed control is set at the idle position, turn the idle mixture screw slowly clockwise until the engine R.P.M. just starts to decrease. Stop and note this screw position. Turn the idle mixture screw slowly counterclockwise, the engine will increase in R.P.M. Continue to slowly turn the screw until the engine R.P.M. starts to decrease. Note this position and turn the mixture screw back clockwise halfway between the two engine R.P.M. drop off positions. The idle mixture adjustment is complete.

Some carburetors came equipped with a main mixture adjusting screw. To adjust the main mixture, follow the steps for idle adjustment.

IDLE SPEED ADJUSTMENT

SCREW

IDLE MIXTURE

SCREW

4

Emissionized Tillotson

Similar in design and operation, the Tillotson emission carburetor uses a fixed main jet with an adjustable idle. The idle circuit has a limiter cap to prevent over richening. The cap is locked onto the adjustment screw in a rich position, allowing only a leaner adjustment. The main is fixed on these, which means that the main mixture limiter is non-functional on Tecumseh built engines (diag. 4a).

In compliance with E.P.A. and C.A.R.B. regulations the following procedure must be followed.

NOTE: These caps can be removed for servicing of the carburetor. Follow these steps.

1.Turn the caps clockwise until they hit the stops.

2.Remove the caps with a pointed instrument such as an awl.

3.Then turn the screws in until softly seated, note thenumberofturns. Thescrewsmustbereinstalled to this same static setting. Replacement of the caps is required to maintain E.P.A. and C.A.R.B. emission compliance.

IDLE MIXTURE

LIMIT SCREW

FIXED MAIN

(MIXTURE SCREW NOT FUNCTIONAL ON MOST TECUMSEH BUILT ENGINES)

IDLE SPEED

ADJUSTMENT

SCREW

4a

11

2-Cycle Engine Speed and Mixture Adjustments:TVS/TVXL840

IDLE SPEED

ADJUSTMENT

HIGH SPEED
ADJUSTMENT
5	HOLDING	STATIC GOVERNOR	6
	SCREW	ADJUSTMENT SCREW
Linkage Location	Static Governor Adjustment

To aid in the proper reassembly of the governor linkage, mark the linkage locations.

To adjust the static governor, loosen the holding screw, rotate the governor arm and slotted shaft in the direction that will open the throttle to the wide open position, and then re-tighten the holding screw.

HSK/HXL840-850

IDLE RPM	HIGH SPEED
ADJUSTMENT	RPM
SCREW	ADJUSTMENT
	SCREW

7

The HXL840 - 850 Series with variable speed control have the following adjustments. Idle speed is set at the carburetor crack screw. High speed is set with the screw shown above. Always check Microfiche card 30 or Parts Smart computer program for correct speed settings.

INCREASE

DECREASE

BEND TAB

8

R.P.M. adjustment of fixed speed models is done by bending the tab as shown.

Governor and Linkage for Air Vane

VANE ASSEMBLY

TO ADJUST HIGH-

SPEED ROTATE

CLOCKWISE TO

INCREASE

COUNTERCLOCKWISE

TO DECREASE 9

BEND TAB TO

ADJUST RPM

DECREASEINCREASE

HORIZONTAL FIXED SPEED	10
PLASTIC AIR VANE GOVERNOR

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.

12

Governors and Linkage for Air Vane - continued

ADJUST RPM BY

LOOSENING SCREW AND

SLIDING BRACKET

DECREASEINCREASE

HORIZONTAL FIXED SPEED

(ALUMINUM AIR VANE GOVERNOR) 11

HIGH SPEED

IDLE RPMRPM

ADJUSTMENTADJUSTMENT

IDLE

MIXTURE

THIS HOLE NOT

PRESENT ON ALL MODELS

SPRING
VERTICAL ENGINE	12
VARIABLE SPEED-REMOTE CONTROL

ADJUST RPM BY			SPRING
LOOSENING SCREW AND
SLIDING BRACKET
		INCREASE
	DECREASE

GOVERNOR LINK

IDLE RPM

ADJUSTMENT

HIGH SPEED

IDLERPM ADJUSTMENT MIXTURE

HORIZONTAL FIXED SPEED

13

THIS HOLE NOT
PRESENT ON ALL
MODELS
SPRING
VERTICAL ENGINE	14
FIXED SPEED-REMOTE CONTROL

	HIGH SPEED RPM
	ADJUSTMENT
IDLE RPM						THIS HOLE NOT
ADJUSTMENTS
		THIS HOLE NOT				PRESENT ON ALL
						MODELS
		PRESENT ON
		ALL MODELS		RPM ADJUSTMENT		SPRING
VERTICAL ENGINE			SPRING
VARIABLE SPEED	15			VERTICAL ENGINE FIXED SPEED			16
MANUAL CONTROL

13

	Static Governor Adjustments
	The purpose of making a static governor adjustment
	is to remove all free-play between the governor
	spool and the carburetor (see illustration). Any free-
	play here will result in hunting/surging or erratic
	running. After completing this procedure, always	THROTTLE
	re-check the engine speeds using the steps outlined
	in the following pages.

To set the static governor, do the following:

1.Be sure the engine is stopped or damage may occur.

2. If equipped with a throttle control, place the throttle in the high speed position.

3. Loosen the governor clamp or screw.

4. Hold the governor arm and link in the W.O.T. (wide open throttle) position, then rotate the shaft or shaft/clip assembly in the same direc- tion and tighten the screw.

5.If engine speed adjustments are needed, follow

the steps described in following pages.

SPRING

CHOKE

GOVERNOR

ROD

NO FREE

PLAYGOVERNOR SPOOL

WIDE OPEN

THROTTLE

CLOSED

THROTTLE

Governor Shaft Pressed In Depth

When assembling governor shaft into a flange or cover mounting boss, refer to this chart for exposed shaft length.

Engine Model	Exposed Shaft Length	Engine Model	Exposed Shaft Length
ECH 90	Mounting flange to top	H 50, 60, 70	Mounting flange to shoulder
ECV 100	1.319 - 1.334"	HH 60, 70	1.283 - 1.293"
H 30, 35	(33.502 - 33.883 mm)	HHM 80	(32.588 - 32.842 mm)
HS 40, 50		HM 70, 80, 100
LAV (all)
LEV (all)		OHV 11-17	Mounting flange to top
OHH (all)		OVM 120	1.350 - 1.365"
OVRM (all)		OVXL 120, 125	(34.290 - 34.671 mm)
TNT 100, 120
TVS (all)		OHM 90-120	Mounting flange to top
VLV (all)		OHSK 90-130	1.085 - 1.100"
			(27.559 - 27.940mm)
TVM (all)	Mounting flange to top
V 50, 60, 70	1.581 - 1.596"	OH 120-180	Mounting flange to top
VH 50, 60, 70	(25.806 - 26.314mm)		1.00"
			(25.400mm)
HH 100, 120	Mounting flange to top
VH 100	1.016 - 1.036"	TVT - V -Twin	Mounting flange to top
	(25.806 - 26.314 mm)		1.196 (3.969 mm)

14

	Small Frame, Vertical and Horizontal*			Retainerless Governor System for Small
	Models: LAV35,40,50 - H25,30,35 - HS40,50 - HSK - HSSK -			Frames*
	TNT100,120 - ECH90 - TVS75,90,105,115,120 - OVRM ALL
	- ECV100,105,110,120
			RETAINING
			RING
				SPOOL
			SPOOL
				UPSET ROLLED
			RETAINING
			RING	SHAFT
			GEAR ASSY.
			(GOV.)
			WASHER	GEAR ASSY.
				(GOV.)
			SHAFT	WASHER
				NOTE: Gear assembly must have .010 - .020 (.25 - .50 mm) end
				play after shaft is installed into flange.
	* As of August 1992, all small frame engines, including VLV40-6.75, use			* As of August 1992, all small frame engines, including VLV40-
				6.75, use a retainerless shaft. Service replacement shafts will
	a retainerless shaft. Service replacement shafts will be retainerless
				be retainerless for all small frame and VLV engines.
	for all small frame and VLV engines.
	VLV*40, 50, 55, 60, 65, 66			Medium Frame Vertical
				Models: TVM125, 140, 170, 195, 220 - V50,60,70 -
				VH50,60,70
	TYPE I	SPOOL	TYPE II	RETAINING
				RING
				SPOOL
	RETAINING		SPOOL
	RING
			UPSET	WASHER
				RETAINING
			RETAINER
	GEAR ASSY.			RING
			SHAFT
	(GOV.)
				GEAR ASSY.
			GEAR ASSY.	(GOV.)
			(GOV.)
				WASHER
		WASHER		SPACER
			WASHER
		IDLER
		GEAR	.010 - .020 (.25-.50 mm)
			CLEARANCE
				SHAFT

NOTE: Gear assembly must have .010 - .020 (.25 - .50 mm) end play after shaft is installed into flange.

*As of August 1992, all small frame engines, including VLV40-6.75, use a retainerless shaft. Service replacement shafts will be retainerless for all small frame and VLV engines.

15

Medium Frame Horizontal

OHM120 - OHSK 80-130

Models: HH60,70 - H50,60,70 - HM70,80,100 -

HMSK

SHAFT

SPOOL

WASHER

ROD ASSY.

RETAINING

RING

(GOV.)

GEAR ASSY.

SPOOL

(GOV.)

WASHER

WASHER

RETAINING

RING

SPACER

GEAR

ASSY.

(GOV)

BRACKET

SHAFT

SCREWS

OVM120, OVXL120, 125 - OHV11-17

OH120, 140, 160, 180

SPOOL

SPOOL

WASHER

RETAINING

RING

GEAR ASSY.

WASHER

(GOV.)

WASHER

GEAR &

SPACER

NOTE; SPACER

SHAFT

MAY BE PART

ASSY.

OF THE GEAR

(GOV.)

ASSEMBLY.

SHAFT

WASHER

(CAPTURED UNDER

NOTE: On models OHV13.5-17, the spacer is cast as part

GEAR)

of the governor gear with the washer placed below the

gear assembly.

16

Engine Speed and Mixture Adjustments

3-5 H.P. Vertical Shaft Engines

NOTE: Starting and operating problems may exist when engines are used at high elevations (over 4,000 feet above sea level). In cases where a fixed main carburetor is used, refer to Bulletin 110 for correction. Engines which are identified as compliant with CARB (California Air Resources Board) or EPA (US Environmental Protection Agency) regulations can NOT be changed from their factory jetting unless specifically authorized.

Before making any speed or carburetor adjustments be sure to adjust the governor and control bracket. See Governor Section of the Booklet.

To adjust the speed control bracket, determine whether the carburetor is an adjustable type, then proceed.

Some carburetors may have a choke lever which is operated by the speed control bracket. To adjust the speed control bracket for full choke operation, loosen the speed control bracket mounting bolts and move the speed control lever to the high speed/full choke position. Next insert a small piece of wire through the hole in the speed control bracket, choke actuating lever, and the choke lever (diag. 18). When all three holes are aligned tighten the mounting bolts.

Once the speed control bracket is adjusted, the main and idle fuel mixtures can be adjusted. Start theengineandallowittowarmuptonormaloperating 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 (lean). Note the position of the screw. Now, turn the screw out (counterclockwise) until the engine begins to run erratic (rich). 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.

NOTE: SOME CARBURETORS HAVE FIXED MAIN JETS. THE ABSENCE OF THE ADJUSTING SCREW INDICATES A FIXED JET AND NO ADJUSTMENT IS NECESSARY.

After adjusting the fuel mixtures, engine speeds can be adjusted. The correct operating speeds are found on Microfiche card 30 of the Tecumseh Master Parts Manual, or the computer parts look-up program (Part Smart). On engines with adjustable carburetors (diag. 19 and 20) the high speed adjustment will be in one of two places. The first location is on the speed control lever (diag. 19).

			** NON-ADJUSTABLE
	* ADJUSTABLE		NO CHOKE
			PRIMER
	MIXTURES, CHOKE			17
	SPEED CONTROL		SMALL WIRE (DRILL BIT)
	MOUNTING BOLTS
			HOLE IN BRACKET

HOLE IN SPEED

CONTROL CHOKE

ACTUATING LEVER

	HOLE IN CHOKE
	LEVER
	18
HIGH SPEED	LOW SPEED
ADJUSTMENT SCREW	ADJUSTMENT SCREW

IDLE MIXTURE		MAIN MIXTURE
SCREW		SCREW	19

17

Engine Speed and Mixture Adjustments - continued

3-5 H.P. Vertical Shaft Engines

	HIGH SPEED	LOW SPEED	SPEED CONTROL
		ADJUSTMENT SCREW
	ADJUSTMENT		MOUNTING BOLTS
	SCREW

COUNTERCLOCKWISE

TO INCREASE SPEED

CLOCKWISE TO

DECREASE SPEED

IDLE

MIXTURE

SCREW

MAIN MIXTURE SCREW

20

The second is on a bracket located between the blower housing and the speed control (diag. 20). Low speed is adjusted by the throttle crack screw on the carburetor (diag. 19 and 20).

It may be necessary to preset the carburetor mixture screws.

Tecumseh Carburetors
Engine Model	Main Pre-set	Idle Pre-set
All models with
float-type carburetors	1-1/2 turn	1 turn
All models with
diaphragm-type
carburetors	1 turn	1 turn

Some speed control brackets are adjusted by loosening the speed control bracket mounting bolts and sliding the bracket all the way to the right and re- tightening the mounting bolts (diag. 21). The high speed adjustment screw is located on the speed control lever (diag.22) Some carburetors are fixed speed and are adjusted by bending the adjusting tab attached to the intake manifold (diag. 23).

After setting the engine speeds recheck the fuel mixtures, then recheck the engine speeds.

	21
HIGH SPEED	LOW SPEED
ADJUSTMENT	ADJUSTMENT SCREW
SCREW

22

SPEED ADJUSTMENT TAB

BEND TO INCREASE SPEED

BEND TO DECREASE SPEED

23

18

Engine Speed and Mixture Adjustments - continued

3-5 H.P. Vertical Shaft Engines

LOW SPEED TAB	HIGH SPEED TAB	BEND	TO INCREASE SPEED
		BEND	TO DECREASE SPEED
HIGH SPEED
PIN POSITION
			BEND CONTROL
			BRACKET TO SET
				RPM
TOOL	DECREASE
(670326)	INCREASE
SNAP IN CONTROL		24	VERTICAL ENGINES	25

GOVERNED / NON-GOVERNED IDLE

With the engine running at its lowest speed, set the governed idle at the designated R.P.M. by bending the idle R.P.M. tab. Next set the non-governed idle by pushing the bottom of the governor lever away from the control brackets, so the throttle lever contacts the idle speed screw. Hold the lever in this position and turn the idle adjustment screw clockwise to increase or counterclockwise to decrease engine idle speed. The setting on the carburetor screw should be set at 600 R.P.M. below the governed idle setting. This setting prevents the throttle plate from closing when going from high speed R.P.M. to low speed R.P.M. If improperly adjusted, the engine could experience an over lean condition.

HIGH SPEED RPM

ADJUSTMENT

SCREW

TVS 115 ENGINE WITH DUAL
SYSTEM CARBURETOR	26

BEND TO INCREASE SPEED

BEND	TO DECREASE SPEED

HIGH SPEED

RPM

ADJUSTMENT

SCREW

IDLE SPEED

CRACK SCREW

VERTICAL SHAFT ENGINES	27

NOTE:

ON REMOTE CONTROL

THIS WILL NOT BEHIGH SPEED ADJUST PRESENT

LOW SPEED ADJUST

TNT 100 VERTICAL ENGINES

28

OVRM

29

19

VLV Governor and Linkage

Governor Adjustment

With the engine stopped, loosen the screw holding the governor clamp and lever. Turn the clamp clockwise, then push the governor lever (connected to the throttle) to a full wide open throttle position. Hold the lever and clamp in this position and tighten the screw.

Linkage Installation

The solid link is always connected from the throttle lever on the carburetor to the lower hole on the governor lever. The shorter bend has to be toward the governor. The governor extension spring is connected with the spring end hooked into the upper hole of the governor lever and the extension end hooked through the speed control lever. To remove the governor spring, carefully twist the extension endcounterclockwisetounhooktheextensionspring at the speed control lever. Do not bend or distort the governor extension spring (diag. 30).

Speed Controls

This engine has an adjustable speed control. Never exceed the manufacturer's recommended speeds.

NOTE:Governor adjustment screw will be a Torx head (T-10) effective August 1, 1996 for E.C. Compliance.

Fixed Speed

High speed governor adjustment is accomplished by bending a tab to increase and decrease engine R.P.M. Effective August 1997 (diag. 31a).

TWIST COUNTERCLOCKWISE

TO DISCONNECT

GOVERNOR SPRING

SHORT BEND LONG BEND

30

HIGH SPEED ADJUSTMENT

COUNTERCLOCKWISE INCREASES SPEED

LOWSPEEDADJUSTMENT

COUNTERCLOCKWISEINCREASESSPEED

31

TOOL 670326

HIGHSPEED	BEND		TO INCREASE SPEED
ADJUSTMENT	BEND			TO DECREASE SPEED	31A
	FIXED SPEED

20

Engine Speed and Mixture Adjustments

5-15 HP Vertical Shaft Engines

The first stepis adjusting the speed control bracket for full choke operation. Loosen the two speed control bracket mounting bolts and move the control lever to the full high speed/full choke position. Insert a piece of wire through the hole in the speed control bracket, the choke actuating lever, and the choke lever (diag. 32). When all three holes are in alignment retighten the speed control bracket mounting bolts.

SMALL PIECE OF WIRE	HOLE IN
HOLE IN CONTROL BRACKET	CHOKE
	ACTUATING
MOUNTING	LEVER
BOLTS

	MOVE THE CONTROL
	LEVER IN THE HIGH	HOLE IN CHOKE LEVER
	SPEED POSITION

The second step is adjusting the main and idle fuel mixtures. Start the engine and allow it to warm up to normal operating temperature (3 - 5 minutes). Set the speed controls to the HIGH or FAST position, then turn the main mixture adjustment screw in (clockwise) slowly until the engine begins to run erratic (lean). Note the position of the screw. Now, turn the screw out (counterclockwise) until the engine begins to run erratic (rich). 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 procedureusedtoadjustthemainmixtureadjustment screw.

NOTE: SOME CARBURETORS HAVE FIXED MAIN JETS. THE ABSENCE OF THE ADJUSTING SCREW INDICATES A FIXED JET AND NO ADJUSTMENT IS NECESSARY.

The third step is setting engine speeds. The correct engine operating speeds are listed on card 30 of the Tecumseh Master parts manual microfiche, or the computer parts look-up program (Part Smart or Plus One). The most common speed control bracket (diag. 33) has the high speed adjustment screw located on the speed control lever. The low speed adjustment screw is the throttle crack screw on the carburetor body. Another common speed control is the governor override system (diag. 34). This system has a similar speed control bracket along with a governor adjustment lever which is attached to the engine block. Both the high speed

32

HIGH SPEED

ADJUSTMENT SCREW

THROTTLE

CRACK

SCREW

IDLE MIXTURE

SCREW

MAIN MIXTURE

SCREW 33

THROTTLE CRACK SCREW

GOVERNOR

ADJUSTING LEVER

	IDLE	HIGH SPEED
	MIXTURE
		ADJUSTMENT
	SCREW
		SCREW

and low speed adjustment screws are located on the governor adjusting lever.

MAIN MIXTURE SCREW

LOW SPEED ADJUSTMENT SCREW

34

21

Engine Speed and Mixture Adjustments - continued

2.5-17.5 HP Vertical Shaft Engines

To adjust high speed on an up/down control (diag.35) bend the adjustment tab. Low speed is adjusted by a screw at the bottom of the control bracket. Both the governor override system and the up/down speedcontrolhaveagovernedidle. Onthese systems it is important to also adjust the throttle crack screw. To adjust the throttle crack screw use your finger to hold the throttle shutter tight against the throttle crack screw and adjust the engine speed to approximately 600 R.P.M. less than the recommended low speed.

After setting the engine speeds recheck the fuel mixtures and double check the engine speeds.

NOTE: Not all engines have fully adjustable carburetors.

It may be necessary to preset the carburetor mixture screws.

THROTTLE CRACK HIGH SPEED ADJUSTMENT TAB

SCREW	BEND	TO INCREASE SPEED
	BEND	TO DECREASE SPEED

		LOW SPEED
IDLE MIXTURE	MAIN MIXTURE	ADJUSTMENT
SCREW	SCREW	SCREW 35

Tecumseh Carburetors

Engine Model	Main Pre-set	Idle Pre-set
All models with
float-type carburetors	1-1/2 turn	1 turn
All codels with
diaphragm-type
carburetors	1 turn	1 turn

CHOKE

HOOKUP

	HIGH SPEED		GOVERNED
			IDLE SPEED
	ADJUSTMENT
			SCREW	IDLE SPEED
	TAB
	THROTTLE			CRACK
	LINK HOOKUP			SCREW
	ALIGNMENT		CHOKE LEVER
	HOLE		AIR GAP
			(.040 - .070")
			(1.0 - 1.8 mm)		IDLE MIXTURE
			BEND TAB TO
			ADJUST		SCREW

TOOL #670326

TVXL220, OHV 11-17 STYLE SPEED CONTROL

36

The idle speed is adjusted by turning the idle speed screw clockwise to increase engine R.P.M. and counterclockwise to decrease R.P.M. Use tool part # 670326 to adjust the high speed engine R.P.M. Place the slotted end of the tool onto the adjustment tab and bend the tab to the left (toward the spark plug end) to increase engine R.P.M. (diag. 36).

NOTE: Be sure that the throttle cable has full travel from wide open throttle to full choke. Hard Starting could result if the cable is not properly adjusted to allow for full choke.

22

Engine Speed and Mixture Adjustments - continued

LOW SPEED TAB	HIGH SPEED TAB	NOTE: ON REMOTE	HIGH SPEED ADJUST
HIGHSPEED		CONTROL THIS
PIN POSITION		WILL NOT	LOW SPEED ADJUST
		BE PRESENT

	DECREASE
	INCREASE
OVRM SNAP IN CONTROL	37		OVRM	38

OVRM		STANDARD TVM ENGINE WITHOUT
	39	GOVERNOR OVERRIDE	40

SPEEDCHANGES APPROXIMATELY 200 RPM PER SLOT

MAIN MIXTURE
SCREW
GOVERNOR ADJUSTING	HIGH SPEED
SCREW (LOW SPEED)
OVM/OVXL,TVM 170, 195 & 220		41	OHV 11-17

Governor Override System for TVM170, 195 and 220 Engines (diag. 41)

This system will be found starting on 1985 production models and will not retrofit onto older engines. It is designed to allow the governor to regulate the low and high speeds of the engine. The high speed is adjusted at the top screw of the override lever; to increase R.P.M. turn the screw out (counterclockwise), to decrease R.P.M. turn the screw in (clockwise). The low speed is adjusted at the bottom screw of the override lever; to increase R.P.M. turn the screw in or clockwise, to decrease R.P.M. turn the screw out or counterclockwise (diag. 41).

23