Tecumseh AH-HSK600 - User manual

Tecumseh
Quick Reference
Service Information
Covers Engine and Transmission Product
Form No.695933 R 7/00

1
Introduction
This booklet contains the quick reference and basic trouble-
shootinginformationpreviouslyfoundonTecumsehwallcharts
and in the Technician's Handbooks.
This booklet is designed to be used as a work bench quick
referenceguidewhenservicingTecumsehenginesandmotion
drivesystems.
Technician's Note:
Tecumseh engines are manufactured to meet EPA and CARB
standards. Asatechnician,itisunlawfultore-calibrateorreplace
afuelnozzleorjet(bowlnut)withapartfromanyothercarburetor
thatwasnotoriginallydesignedforthatengine. Allspeedadjust-
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.

2
TVS TVXL HSK HXL
TC200 TC300
AV520/600 TVS600 AH/HSK600 AH520
TCH200/ 300
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.
Torqueslistedareintendedtocoverhighlycriticalareas. Moreextensivetorquesarefound
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 • • • •
FlywheelNut 360-420 41-47.5 • • • •
AdapterPlateto Cylinder 160-220 18-25 • •
TC TWO-CYCLE ENGINE SERIES
Location Inch lbs. Torque Nm Engine Designation
Cylinder to Crankcase 80-95 9-11 •••
Crankcase Cover to Crankcase 70-100 8-11 •••
FlywheelNut 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 • • • •
FlywheelNutAVIndustrial(PointIgnition) 216-300 24.5-34 • •
(670 Series AV 520 and All AV 600)
FlywheelNut(C.D.Ignition) 264-324 30-36.5 • • • •

3
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.
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.
(CONTINUED ON NEXT PAGE)
Check fuel supply
and fuel cap vent
Wet Dry
Defective
spark plug
Improper fuel mix
or stale fuel
Carburetion
problems due to
flooding, over
priming, etc.*
Restricted
air filter
Exhaust ports
plugged
Crankcase seals
or gaskets leaking
Ignition System
Damaged reed, port
plugs, seals or
gaskets
Poor
compression
Restriction in
fuel system (filter,
screen)
FUEL SYSTEM
Engine Will
Not Start
Check if spark
plug is wet or dry
Review with customer
priming or choking
procedure
(3-5 primes, if
equipped, waiting 2
seconds between
each prime)
Carburetion problem*
(bad bowl gasket)

4
NOTE: Refer to Technician's Handbook for a more detailed list of remedies.
Two Cycle Troubleshooting - continued
IGNITION SYSTEM
Engine Will
Not Start
Replace spark plug
Isolate engine from all
equipment (disconnect
wiring harness), repeat
test
No Spark
Check for spark
Set proper point gap,
check condensor and
timing (if equipped)
Check electric starter
if applicable
Set proper air gap on
external coil
Check flywheel for
correct key, damaged
key or key adaptor
Test coil for
intermittent or weak
spark
Equipment problem,
check switches, wiring
and equipment
controls
Spark
Parasitic load too high Test ignition module
Engine problem,
check for shorts or
grounds in wiring
No Spark
Spark

5
TVM & TVXL 170-195-220
Torque Specifications
FOUR-CYCLE LIGHT FRAME ENGINE SERIES
(TVS, TNT, ECV, LAV, LEV, H, HS, OHH, OVRM and VLV)
Location Inch lbs. Torque Nm Engine Designation
Rocker Arm Stud Lock Nut 100-140 11-16 • •
ConnectingRod 95-110 11-12.5 • • • • • • • • • •
CylinderHead 160-210 18-24 • • • • •
CylinderHead 220-240 25-27 • •
CylinderHead 180-220 20.5-25 •
MountingFlangeorCylinderCover 100-130 11-14.5 • • • • • • • • • •
FlywheelNut(CastIron) 500-600 42-50 • • • • • • • • • •
FlywheelNut(Aluminum) 400-500 45-56.5 • • • • • • • • • •
TVS TNT ECV LAV H/HSK HS/HSSK OVRM VLV LEV
OHH
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.
Torqueslistedareintendedtocoverhighlycriticalareas. Moreextensivetorquesarefound
in the respective repair manual.
Location Inch lbs. Nm Engine Designation
Torque
HM/HMSK70-100 OVM/OVXL, OHV120-125
OHSK80-130 OHM120
TVM125, 140
H50-60 V70 H70
OHV135-145 203 Series OHV15-17.5 204 Series
OHV11-13,OHV110- 135, 206 Series
FOUR-CYCLE MEDIUM FRAME ENGINE SERIES
(TVM, TVXL, H, V, HM, OVM, OVXL, OHM, OHSK and OHV)
ConnectingRod 160-180 18-20.5 • •
ConnectingRod 200-220 22.5-25 • • • • • •
ConnectingRod 200-240 22.5-27 •
CylinderHead Bolts 220-240 25-27 • •
CylinderHead Bolts 180-240 20.5-27 • •
CylinderHead Bolts 160-210 18-24 • • • • • •
Rocker Adj. Lock Screw 65-80 7-9 •
Rocker Arm Stud Lock Nut 110-130 12.5-14.5 •
RockerArm HexJam Nut 15-20 2• •
Rocker Arm Studs 170-210 19-24 • • •
Rocker Arm Box to Head 75-130 8.5-14.5 • •
RockerBoxCover 15-20 2• •
RockerBoxCover(FourScrew) 40-65 4.5-7 • • •
MountingFlangeorCylinderCover 100-130 11-14.5 • • • •
MountingFlangeorCylinderCover 110-140 12.5-16 • • • • • •
Flywheel Nut 400-550 45-62 • • • •
FlywheelNut(External Ignition) 600-800 68-90 • • • • • •

6
Torque Specifications - continued
HH VH OH
Location Inch lbs. Nm Engine Designation
Torque
TVT
FOUR-CYCLE LARGE FRAME ENGINE SERIES (CAST IRON BLOCK HH, VH and OH)
ConnectingRod 86-110 10-12.5 • • •
CylinderHead 180-240 20.5-27 • • •
MountingFlange&CylinderCover 100-130 11-14.5 • • •
RockerArmShafttoBox 180-220 20.5-25 •
RockerArmBox toCylinderHead 80-90 9-10 •
FlywheelNut 600-660 68-74.5 • • •
FOUR-CYCLE HEAVY FRAME ENGINE SERIES (V-TWIN)
Location Inch lbs. Nm Engine Designation
Torque
ConnectingRod 200-220 22.5-25 •
CylinderHeadBolts 220-240 25-27 •
RockerArmJamNut 110-130 12.5-14.5 •
RockerArmCoverMountingScrew 52 6•
MountingFlange/CylinderCover 240-260 27-29 •
FlywheelNut 600-800 68-90 •

7
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.
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.
Improper or
stale fuel
Check if spark plug is
wet or dry
FUEL SYSTEM
Engine Will
Not Start
Defective
spark plug
Wet
Restricted air filter
Carburetion problems
due to flooding, over
priming, etc.*
Ignition system
Review with the
customerproper
priming procedure
(3-5 primes, waiting
2 seconds between
each prime)
Dry
Poor
compression
Check fuel supply and
fuel cap vent
Restriction in fuel
system(filter)
Carburetion problem*
(bad bowl gasket)
If equipped with a
choke, check for full
travel. Check throttle
cable and control for
properadjustment.

8
Four Cycle Troubleshooting - continued
NOTE: Refer to Technician's Handbook for a more detailed list of remedies.
IGNITION SYSTEM
Engine Will
Not Start
No Spark
Spark
Check for
spark
Spark
Set proper point gap,
check condensor and
timing
No Spark
Replace spark plug
Isolate engine from all
equipment (disconnect
wiring harness), repeat
test
Parasitic load too
high
Test coil for
intermittent or weak
spark
Set proper air gap on
external coil
Check flywheel for
correct key, damaged
or sheared key
Test ignition
module
Engine problem,
check for shorts or
grounds in wiring
Equipment problem,
check switches,
wiring and
equipment controls

9
1
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. Thissettingisapproximate. Thiswillallow
theenginetobestartedsothecarburetorcanbefine
tuned.
Starttheengineandletitwarmupforapproximately
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.
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. TurnthescrewcounterclockwiseuntilenginejuststartstosputterordropsinR.P.M.. Remember
this location. Turn the screw clockwise until it is halfway between your first position where the engine
falteredandyourlastpositionwheretheenginestartedtosputter. Thiswillbetheoptimumlowspeedsetting
on your carburetor.
Nextrun theengine atgoverned speed. Thehigh speedadjustments aremade basicallythe 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.
Turnthemixture adjustmentscrewfinger tight totheclosed position,thenone (1) turnoutfrom theclosed
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: Iftheenginefaltersorstopsafterthechokeleverismovedtothe"OFF"position,openthemixture
adjusting screw 1/4 turn (counterclockwise) and restart the engine.
Withtheenginerunning,placethespeedcontrolinthe"slow"positiontomakemixtureadjustments. Turn
the mixture screw slowly clockwise from the NORMAL setting until the engine falters. Remember this
location. Turnthescrew counterclockwise until theenginejuststartstosputterordropsinR.P.M. Remember
this location. Turn the screw clockwise until it is halfway between your first position where the engine
falteredandyourlastpositionwheretheenginestartedtosputter. Thiswillbetheoptimumsettingonyour
carburetor.
IDLE MIXTURE
SCREW MAIN MIXTURE
SCREW
NOTE: If no tension
spring is present, it
may be a fixed jet.

10
TC Series Governor Adjustment
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
1
4
9
7
6
HIGH SPEED
GOVERNOR
ADJUSTMENT INSERT THROTTLE
LINK AND SPRING
HERE
OUT TO INCREASE
IN TO DECREASE
TYPE I
(style 1)
TYPE I
(style 2)
SPEED
ADJUSTING
LEVER
2
3
SPEED
ADJUSTING
LEVER
TYPE II:
(style 3)
Threedifferentstylesofgovernorsystemsareused
onTCengines. 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
reachoperating temperature. Make surethe air
filter(ifequipped)iscleanandthechokeisinthe
offposition.
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
card30, or acomputerparts look-upprogramto
obtain the recommended engine speeds.
3. Using the applicable illustration, either bend the
speedadjustinglever toward thesparkplugend
ofthe engineto decreasehigh speed R.P.M.,or
bendtheleverintheoppositedirectiontoincrease
R.P.M. On TC Type II engines, turn the speed
adjustingscrewouttoincreaseorintodecrease
enginehighspeedR.P.M. Ifthespeedadjustment
screwisturnedouttoincreasetheengineR.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
controltothelowestspeedpositionandadjusting
thelowspeedadjustmentscrewonthecarburetor.
BEND TO INCREASE SPEED
BEND TO DECREASE SPEED
Spring Color Spring Position
Orange or Green 1
Pink, Red, or Black 2
SPRING
SPRING
POSITION 1
POSITION 2
3
24
15
8
HOOK
SPRING ON
NOTCH
HOOK
SPRING ON
NOTCH
HOOK
SPRING ON
NOTCH

11
IDLE MIXTURE
SCREW
IDLE SPEED ADJUSTMENT
SCREW
4
Carburetor Pre-Set and Adjustment
BoththeWalbroandtheTillotsoncarburetorsused
on TC engines have non-adjustable main mixture
jets. Only the idle mixture is adjustable by turning
theidlemixturescrew. Usethefollowingprocedure
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(after3-5minutes). Asthespeedcontrol
issetattheidleposition,turntheidlemixturescrew
slowlyclockwise untilthe engine R.P.M. juststarts
todecrease. Stopandnotethisscrewposition. Turn
theidlemixturescrewslowlycounterclockwise,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
mixtureadjustingscrew. Toadjustthemainmixture,
follow the steps for idle adjustment.
Walbro(WTA,WT)andTillotson(HU)DiaphragmAdjustment
4a
EmissionizedTillotson
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
leaneradjustment. Themainisfixedonthese,which
meansthatthemainmixturelimiterisnon-functional
on Tecumseh built engines (diag. 4a).
IncompliancewithE.P.A.andC.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. Turnthecaps clockwise untiltheyhit the stops.
2. Remove the caps with a pointed instrument
such as an awl.
3. Thenturnthescrews in untilsoftlyseated,note
thenumberofturns. Thescrewsmustbereinstalled
to this same static setting. Replacement of the
capsisrequiredtomaintainE.P.A.andC.A.R.B.
emission compliance.
FIXED MAIN
(MIXTURE SCREW
NOT FUNCTIONAL ON
MOST TECUMSEH
BUILT ENGINES)
IDLE SPEED
ADJUSTMENT
SCREW
IDLE MIXTURE
LIMIT SCREW

12
2-CycleEngineSpeedandMixture Adjustments:TVS/TVXL840
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.
Todisassemble, remove chokeshutterwith needle-nosepliers;the vane assemblymay then beremoved
from the carburetor.
9HORIZONTAL FIXED SPEED PLASTICAIR VANE GOVERNOR 10
BEND TAB TO
ADJUSTRPM
INCREASE
DECREASE
Governor and Linkage for Air Vane
IDLE RPM
ADJUSTMENT
SCREW
HIGH SPEED
RPM
ADJUSTMENT
SCREW
TheHXL840-850Serieswithvariablespeedcontrol
havethe following adjustments.Idle speedisset 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.
R.P.M. adjustment of fixed speed models is done
by bending the tab as shown.
HSK/HXL840-850
IDLE SPEED
ADJUSTMENT
HIGH SPEED
ADJUSTMENT
5HOLDING
SCREW
Linkage Location
To aid in the proper reassembly of the governor
linkage, mark the linkage locations.
6
Static Governor Adjustment
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
openposition,andthenre-tightentheholdingscrew.
VANEASSEMBLY
STATICGOVERNOR
ADJUSTMENTSCREW
7
8
BEND TAB
TO ADJUST HIGH-
SPEED ROTATE
CLOCKWISE TO
INCREASE
COUNTERCLOCKWISE
TO DECREASE
DECREASE
INCREASE

13
HORIZONTAL FIXED SPEED
15
VERTICAL ENGINE
FIXED SPEED-REMOTE CONTROL
VERTICAL ENGINE
VARIABLE SPEED-REMOTE CONTROL
HORIZONTAL FIXED SPEED
(ALUMINUM AIR VANE GOVERNOR)
Governors and Linkage for Air Vane - continued
13
ADJUST RPM BY
LOOSENING SCREW AND
SLIDING BRACKET
ADJUST RPM BY
LOOSENING SCREW AND
SLIDINGBRACKET
SPRING
IDLE RPM
ADJUSTMENTS
HIGH SPEED RPM
ADJUSTMENT
THIS HOLE NOT
PRESENTON
ALL MODELS
SPRINGVERTICAL ENGINE
VARIABLESPEED
MANUAL CONTROL
11
IDLE RPM
ADJUSTMENT
THIS HOLE NOT
PRESENT ON ALL
MODELS
SPRING
12
GOVERNOR
LINK
14
RPMADJUSTMENT
THIS HOLE NOT
PRESENT ON ALL
MODELS
SPRING
VERTICAL ENGINE FIXED SPEED 16
THIS HOLE NOT
PRESENT ON ALL
MODELS
SPRING
HIGH SPEED
RPM
ADJUSTMENT
IDLE
MIXTURE
HIGH SPEED
RPM ADJUSTMENT
IDLE
MIXTURE
IDLE RPM
ADJUSTMENT
INCREASE
DECREASE
INCREASE
DECREASE

14
Static Governor Adjustments
Thepurposeofmakingastaticgovernoradjustment
is to remove all free-play between the governor
spoolandthecarburetor(seeillustration). Anyfree-
play here will result in hunting/surging or erratic
running. After completing this procedure, always
re-checktheenginespeedsusingthestepsoutlined
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. Ifenginespeedadjustmentsareneeded,follow
the steps described in following pages.
Whenassemblinggovernorshaftintoaflangeorcovermountingboss,refertothischartforexposedshaft
length.
Governor Shaft Pressed In Depth
EngineModel ExposedShaftLength
ECH 90 Mounting flange to top
ECV 100 1.319 - 1.334"
H 30, 35 (33.502 - 33.883 mm)
HS 40, 50
LAV(all)
LEV (all)
OHH (all)
OVRM (all)
TNT 100, 120
TVS (all)
VLV (all)
TVM (all) Mounting flange to top
V 50, 60, 70 1.581 - 1.596"
VH 50, 60, 70 (25.806 - 26.314mm)
HH 100, 120 Mounting flange to top
VH 100 1.016 - 1.036"
(25.806 - 26.314 mm)
EngineModel ExposedShaftLength
H 50, 60, 70 Mounting flange to shoulder
HH 60, 70 1.283 - 1.293"
HHM 80 (32.588 - 32.842 mm)
HM 70, 80, 100
OHV 11-17 Mounting flange to top
OVM 120 1.350 - 1.365"
OVXL 120, 125 (34.290 - 34.671 mm)
OHM 90-120 Mounting flange to top
OHSK 90-130 1.085 - 1.100"
(27.559 - 27.940mm)
OH 120-180 Mounting flange to top
1.00"
(25.400mm)
TVT - V -Twin Mounting flange to top
1.196 (3.969 mm)
SPRING
GOVERNOR
SPOOL
NO FREE
PLAY
THROTTLE CHOKE
WIDE OPEN
THROTTLE
CLOSED
THROTTLE
GOVERNOR
ROD

15
*AsofAugust1992,allsmallframeengines,includingVLV40-6.75,use
a retainerless shaft. Service replacement shafts will be retainerless
for all small frame and VLV engines.
MediumFrame Vertical
Models: TVM125, 140, 170, 195, 220 - V50,60,70 -
VH50,60,70
VLV*40, 50, 55, 60, 65, 66
Small Frame, Vertical and Horizontal*
Models: LAV35,40,50 - H25,30,35 - HS40,50 - HSK - HSSK -
TNT100,120 - ECH90 - TVS75,90,105,115,120 - OVRM ALL
- ECV100,105,110,120
Retainerless Governor System for Small
Frames*
RETAINING
RING
SPOOL
RETAINING
RING
GEAR ASSY.
(GOV.)
WASHER
SHAFT
SPOOL
SHAFT
WASHER
GEAR ASSY.
(GOV.)
TYPE I SPOOL
IDLER
GEAR
WASHER
GEAR ASSY.
(GOV.)
RETAINING
RING
TYPE II
WASHER
GEAR ASSY.
(GOV.)
SHAFT
SPOOL
UPSET
RETAINER
SHAFT
SPACER
WASHER
RETAINING
RING
WASHER
SPOOL
RETAINING
RING
GEAR ASSY.
(GOV.)
*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.
NOTE: Gear assembly must have .010 - .020 (.25 - .50 mm) end
play after shaft is installed into flange.
*AsofAugust1992,allsmallframeengines,includingVLV40-6.75,use
a retainerless shaft. Service replacement shafts will be retainerless
for all small frame and VLV engines.
NOTE: Gear assembly must have .010 - .020 (.25 - .50 mm)
end play after shaft is installed into flange.
UPSET ROLLED
.010 - .020 (.25-.50 mm)
CLEARANCE

16
SHAFT
WASHER
BRACKET
SPOOL
RETAINING
RING
GEAR
ASSY.
(GOV)
SCREWS
ROD ASSY.
(GOV.)
SPOOL
WASHER
RETAINING
RING
GEAR ASSY.
(GOV.)
WASHER
SPACER
SHAFT
SPOOL
WASHER
RETAINING
RING
GEAR ASSY.
(GOV.)
WASHER
SPACER
SHAFT
NOTE; SPACER
MAY BE PART
OF THE GEAR
ASSEMBLY.
SPOOL
WASHER
GEAR &
SHAFT
ASSY.
(GOV.)
WASHER
(CAPTURED UNDER
GEAR)
Medium Frame Horizontal
Models: HH60,70 - H50,60,70 - HM70,80,100 -
HMSK
OVM120, OVXL120, 125 - OHV11-17
OHM120 - OHSK 80-130
OH120, 140, 160, 180
NOTE: OnmodelsOHV13.5-17,thespaceriscastaspart
of the governor gear with the washer placed below the
gear assembly.

17
MAIN MIXTURE
SCREW
17
18
**NON-ADJUSTABLE
NO CHOKE
PRIMER
*ADJUSTABLE
MIXTURES, CHOKE
SMALL WIRE (DRILL BIT)
HOLE IN BRACKET
HOLE IN SPEED
CONTROL CHOKE
ACTUATING LEVER
HOLE IN CHOKE
LEVER
LOW SPEED
ADJUSTMENT SCREW
IDLE MIXTURE
SCREW
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
4,000feetabovesea level). In cases where a fixed
main carburetor is used, refer to Bulletin 110 for
correction. Engines which are identified as
compliantwithCARB(CaliforniaAirResources
Board) or EPA (US Environmental Protection
Agency) regulations can NOTbe changed from
their factory jetting unless specifically
authorized.
Beforemakinganyspeedorcarburetoradjustments
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.
Somecarburetorsmayhaveachokeleverwhichis
operatedbythespeedcontrolbracket.Toadjustthe
speedcontrolbracketforfullchokeoperation,loosen
thespeedcontrolbracketmountingboltsandmove
thespeedcontrollevertothehighspeed/fullchoke
position. Next insert a small piece of wire through
theholeinthespeedcontrolbracket, chokeactuating
lever,andthechokelever(diag.18). Whenallthree
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
untiltheenginebeginstorunerratic(lean). Notethe
position of the screw. Now, turn the screw out
(counterclockwise) until the engine begins to run
erratic(rich). Turnthescrewin(clockwise)midway
between these two positions. This will be the best
setting.
SetthespeedcontroltotheIDLEorSLOWposition.
Adjust the idle mixture screw following the same
procedure used to adjust the main mixture
adjustment.
NOTE: SOME CARBURETORS HAVE FIXED
MAINJETS. THEABSENCEOFTHEADJUSTING
SCREW INDICATES A FIXED JET AND NO
ADJUSTMENT IS NECESSARY.
Afteradjustingthefuelmixtures,enginespeedscan
be adjusted. The correct operating speeds are
foundonMicrofichecard30oftheTecumsehMaster
PartsManual,orthecomputerpartslook-upprogram
(PartSmart). Onengineswithadjustablecarburetors
(diag.19and20)the high speedadjustment willbe
in one of two places. The first location is on the
speed control lever (diag. 19).
SPEED CONTROL
MOUNTING BOLTS
HIGH SPEED
ADJUSTMENT SCREW
19

18
HIGH SPEED
ADJUSTMENT
SCREW
LOW SPEED
ADJUSTMENT SCREW
IDLE
MIXTURE
SCREW
MAIN MIXTURE SCREW
COUNTERCLOCKWISE
TO INCREASE SPEED
CLOCKWISETO
DECREASESPEED
SPEED CONTROL
MOUNTING BOLTS
20
Engine Speed and Mixture Adjustments - continued
3-5 H.P. Vertical Shaft Engines
21
HIGH SPEED
ADJUSTMENT
SCREW
LOW SPEED
ADJUSTMENT SCREW
22
SPEED ADJUSTMENT TAB
BEND TOINCREASESPEED
BEND TODECREASESPEED
23
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).
Itmaybenecessarytopresetthecarburetormixture
screws. Tecumseh Carburetors
EngineModel 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
looseningthespeedcontrolbracketmountingbolts
andslidingthebracketallthewaytotherightandre-
tightening the mounting bolts (diag. 21). The high
speed adjustment screw is located on the speed
control lever (diag.22) Some carburetors are fixed
speedandareadjustedbybendingtheadjustingtab
attached to the intake manifold (diag. 23).
After setting the engine speeds recheck the fuel
mixtures, then recheck the engine speeds.

19
TNT 100 VERTICAL ENGINES
25
26
BEND CONTROL
BRACKET TO SET
RPM
VERTICALENGINES
TVS115 ENGINEWITH DUAL
SYSTEMCARBURETOR
BEND TOINCREASESPEED
BEND TODECREASESPEED
HIGH SPEED RPM
ADJUSTMENT
SCREW
GOVERNED / NON-GOVERNED IDLE
Withtheenginerunningatitslowestspeed,setthegovernedidleatthedesignatedR.P.M.bybendingthe
idleR.P.M. tab. Nextsetthenon-governedidlebypushingthe bottomofthegovernorleverawayfromthe
controlbrackets,sothethrottlelevercontactstheidlespeedscrew. Holdtheleverinthis positionandturn
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
preventsthethrottleplatefromclosingwhengoingfromhighspeedR.P.M.tolowspeedR.P.M. Ifimproperly
adjusted, the engine could experience an over lean condition.
VERTICAL SHAFT ENGINES
28
BEND TOINCREASESPEED
BEND TODECREASESPEED
27
HIGHSPEED
RPM
ADJUSTMENT
SCREW
IDLESPEED
CRACKSCREW
NOTE:
ON REMOTE CONTROL
THIS WILL NOT BE
PRESENT
LOW SPEED ADJUST
HIGH SPEED ADJUST
OVRM 29
Engine Speed and Mixture Adjustments - continued
3-5 H.P. Vertical Shaft Engines
LOWSPEED TAB HIGH SPEED TAB
DECREASE
INCREASE
HIGH SPEED
PINPOSITION
TOOL
(670326)
SNAP IN CONTROL 24