Toro 51603 Operating instructions

GAS TRIMMER GUIDE, MODELS 51630, 51603, 51604
Table of Contents – Page 1 of 1
FOREWORD
GENERAL INFORMATION
MAINTENANCE PROCEDURES
AIR CLEANER MAINTENANCE
EXHAUST SYSTEM MAINTENANCE
FLEXIBLE DRIVE SHAFT MAINTENANCE
CARBURETOR ADJUSTMENTS -- MODEL TC-1 500 WITH TILLOTSON
CARBURETOR ADJUSTMENT -- MODELS TC-300, TC-400 WITH WALBRO
TROUBLESHOOTING AND TEST PROCEDURES
DISASSEMBLY, REPAIR, REASSEMBLY INSTRUCTIONS
WALBRO CARBURETOR OPERATION
CUTTER HEAD TROUBLESHOOTING
CLUTCH REPAIR

GASOLINE POWERED TRIMMER
MAINTENANCE
& REPAIRGUIDE
MODEL NO. 51630 1000001 & UP
2000001 & UP
2000001 & UP
COPYRIGHT(C) ALL RIGHTS RESERVED
The Tor0 Company - 1982
MINNEAPOLIS, MN 55420 U.S.A.
Form 492-0266

FOREWORD'
This Maintenance and Repair Guide will provide you with complete information necessaryto
accomplish the maintenanceand repair of gasoline-powered flexible line trimmers powered by
the new line of the lightweight two-cycle engines manufacturedby The Tor0Company
The number of repair procedures for this lineof engine;s has been limited for simplicity and
economyTherepairsare easy to accomplish.evenforoperators or mechanicswho have
limitedexperience in the repairof small two-cycle engines
Should you require additional information concerning these trimmers. we urge you to write to
us Addressinquiriesto:
The Tor0 Company
8111 Lyndale Avenue South
Minneapolis MN 55420
Attn..Service Department
TABLE OF CONTENTS
PAGE
Two-cycle Engine -Theory of Operation 1
Engine operation
1
EngineSpecifications 3
Engine Torque Specifications 3
Air CleanerMaintenance 4
GeneralInformation 1-3
Maintenance Procedures ...................................... 4-7
ExhaustsystemMaintenance 4
FlexibleDriveShaftMaintenance 5
Carburetor Adjustments; Model TC-1500 (Tillotson Carburetor) 5-6
Carburetor Adjustments; Models TC-300 & TC-400 (Walbro carburetor) 6-7
TestingCylinderCompression 7
CheckingFuel Tank venting 8
EngineTroubleshootingChart 9
Troubleshooting andTest Procedures 7-9
Preliminary Checks: 7
CompressionTest Procedure 7
CheckingFor Spark 8
CheckingFuelTank 8
CheckingtheStopSwitch 8
Disassembly.Repair. Reassembly Instructions 10-18
Trimmer EngineRemoval. Disassembly. Replacement 10
Starter Rope Replacement 12
Starter Assembly Replacement ......................................
Walbro Carburetor Servicing 14
Cutter HeadTroubleshooting Chart 16
WalbroCarburetorOperation 13
Clutch Repair 17
Automatic Line FeedRepair 18

GENERAL INFORMATION
Two-cycle Engine Theory of Operation
Two-cycleenginesareusedon TORO Trimmers
becauseof their:
1. Light weight.
2. Excellent power-to-weight ratio
3. Ability tooperate in any position
4.Easy maintenance
5. Simpleconstruction
The TORO Two-cycle Engineused onthe TC-1500,
TC-300 and TC-400 Trimmers is a third-port, loop-
scavenged design. This design name describes the
path of the fuel/air mixture into the crankcase and
combustion chamber, andtheexhausting of spent
gases (Fig. 1
st Port
\
transfer
(Both
Cylinder)
Figure 1
In aloop-scavengedengine with a third-port, the
flow of thefuel/airmixturecanbedescribed as
follows: (SeeFig. 1).
1. The fresh fuel/air mixture enters the crankcase
through the third-port on the side of the cylinder.
The oil in thefuel/airmixturelubricatesthe
moving parts within the crankcase.
2. The fuel/airmixtureistransportedthroughthe
fueltransferportstothecombustion chamber
where it iscompressed, ignited, andthen expelled
from the engine through the exhaustport.
Engine Operation ,
The piston closes all engine portsas it movestoward
the combustion chamber(Fig. 2). The moving piston
creates high pressure in the combustion chamber
and partial vacuum in the crankcase.
Figure 2
Compression Stroke
At a point slightly before topdead center(BTDC) of
the pistontravel, the spark from the plug ignites the
fuel air mixture(Fig. 3). Also, at this time, the third-
port opens allowingthefreshfuel/airmixtureto
rushintothecrankcasetoequalizethepartial
vacuum.
Spark Ignites
Fuel/Air Mixture
I
Piston at or
Near
T.D C.
Exhaust Port
Closed
Open
FreshFuel/AirMixture
Lubricates
Moving Parts
Figure 3
Ignition
1

GENERAL INFORMATION
Thee expandingbanding gases fromtheburningfuel in the
combustionchamberforcethepiston downthe
cylinder,closing thethird-port andincreasingthe
pressure in thecrankcase.Atapointapproaching
the bottomof the stroke, the exhaust portopens and
the burntgases begin to be expelled from thecom-
bustion chamber(Fig. 4).
Mixture Compressed
Closed
Figure 4
Power/Exhaust
At a point of piston travel slightly before bottomdead
center (BBDC) the fuel transferports, on thesides c
the cylinderwalls,areuncoveredandthe com-
pressedfuel/air mixture in thecrankcase is allowed
to enter the combustion chamber where they help
expel the burnt gases and charge the chamber fa
the following pistonstroke (Fig. 5).
Figure 5
Exhaust/Fuel transfer

ENGINE SPECIFICATIONS
TC TC300
TC400
(Model51630)(Model51603) (model51604)
32:1
or unleadedregularleaded
Genuine TOR0 Two-CycleOilor otherhighquality two-cycle oil,BIA
approved
.40 (13.5 oz.)
Fillotson ModelSP-1A WalbroWa-120serieswith
with selfcontained fuel self containedfuel
pump,acceleratorpumpand filter screen
pumpand filter screen
Factoryadjustedand Factory adjusted and testrun.
Procedures-pp. testrun. Adjusting Procedures
Solid state,-capacitive discharge ignition(CD1)
1.29-1.67mm(-051-066in.)BTDC
22degreesBTDC
.20-.30mm (.008-.012 in.)
ENGINE TORQUE SPECIFICATIONS
t
CooIing~Shroud Screws
Carburetor Mounting Screws
NOTE: MetricTorque Conversions:
inch-pounds X1.152= kilogram-centimeters
foot-pounds X .1383 = kilogram-meters
TORQUE-Kg-cm/Kg-m
~.TORQUE-in.-lbs/ft-lbs
.35-41Kg-cm 30-45in.-lbs.
23-35Kg-cm 20-30in-lbs
29-40Kg-cm-15-35 in.-lbs.
12-23Kg-cm10-20in-lbs
29-40Kg-cm
23-35kg-cm 25-35in.-lbs.
3

MAINTENANCE PROCEDURES
AIR CLEANER MAINTENANCE
Check and clean the foamair cleaner element every
eight operating hours, and the felt air cleaner once a
season.
1. Remove the air cleaner cover by pressing up on
thebottom of the cover to releasethelower
mounting tab and pressing in on front of thecover
to release the upper tab. DO NOT FORCE.
2. Carefully remove the filter clip or filter retainer.
Remove the foam filter and felt filter (Figures 6
and 7).
Air Cleaner Housing
Press Here to Remove
Figure 6
Air CleanerHousing
Felt Filter
3. Wash the foam filter in asoap and water solution
and dry thoroughly. If the filter shows any signof
damage or deterioration, replace it.
4. Saturate the foam filter with one teaspoon(5ml)
SAE 30 oil. Squeeze the filter to distribute the oil
evenly andtoremoveexcess oil. A damp element
is necessary to ensure proper functioning of the
air cleaner.
5. Inspect the felt filter.If it isdirty, wash it in clean
solvent and air dry it. If the filter showsany sign
of ,damage it must be replaced.
6. Reinstall the felt filter, foam filter, and filter clipor
retainer in the air cleaner housing (Figures 6 and
IMPORTANT:Make sure thepeg in theair cleaner
housingfitsthroughthesmallhole in the felt
filter. Both filters must cover the opening in the
air, cleaner housing.
7. Reinstallthe aircleaner cover bypressingthe
cover in, and up, behind the choke lever and then
pressthe lower mounting tab into the hole in the
engine housing. DO NOT FORCE.
7).'
EXHAUST SYSTEM MAINTENANCE
NOTE: Some states require that aspark arrester be
attached to the muffler if the trimmer is tobe used in
forested areas, or on other public lands. Be sure to
check your local state laws before using your gaso-
line powered trimmer.
An important part of the maintenance procedure for
all two-cycle engines is the cleaningor decarboning
of the exhaustsystem.This is done to assure the
unobstructedflow of exhaust gases andparticles
from the combustion chamber. A severely carboned
muffler, spark arrester screen. and/or exhaust port
will cause poorstarting and low power outputof the
trimm'er engine.
1. Remove the muffler shield, screen, mufflerand
2. Soak the screen in solvent and remove the carbon
build-up with a wire brush,or replace thescreen.
3. Clean the muffler baffle holes inside the muffler
exhaust gasket.
with a screwdriver.
4. Check thecylinderexhaust port.If necessary,
remove the carbon deposits from the port using a
wiiden stick (Fig. 8).
Figure 8
4

IMPORTANT:WHENREMOVINGCARBONDE-
POSITS,CLOSETHEPORT WITH THEPISTON
TOPREVENT LOOSE CARBON DEPOSITS FROM
FALLING INTO THE CYLINDER. TAKE CARE NOT
TOSCRATCHTHEPISTON. DONOTUSE A
METALTOOL SUCHAS A SCREWDRIVER.
5. Reassemble the mufflercomponents. Useafresh
exhaust gasket.
FLEXIBLE DRIVE SHAFT MAINTENANCE
The flexibledriveshafthasbeenlubricatedatthe
factory. After approximately every 40 hours of opera-
tion, the shaft should be removed from its housing
and its entire surface coated with a No.2 general
,purpose, lithium-base grease. To remove the shaft,
loosenthelowerhandleand slide it towardthe
engine assembly to expose the clamp. Loosen the
clampand separate the upper andlowertube as-
semblies. The shaft will then be able to be pulled
from the lower tube(Fig. 9).
Figure9
CARBURETOR ADJUSTMENTS MODEL
TC-1500WITH TILLOTSON CARBURETOR
The carburetor has been adjusted at thefactory, but
an adjustment may be required to compensate for
differences in fuel,temperatureandaltitude. The
TillotsoncarburetorusedontheTC-1500isnot
serviceable. Ifcarburetiondifficultiescannot be
corrected by adjustment, thecarburetormustbe
replaced.
IMPORTANT:The correct amountof line must be fed
fromthetrimmer spoolbeforeadjustingthecar-
buretor to ensure thattheengineisadjustedfor
operationwhile under load..
1.Remove aircleaner coverby pressingup on
bottom ofcover to release lowermountingtab
and pressing in on frontof covertorelease upper
tab. DO NOT FORCE (Fig. 10).
Figure 10
CAUTION: THEENGINEMUST BE
RUNNING SO FINAL ADJUSTMENTS OFTHE
CARBURETORCANBEPERFORMED.
AL INJURY,KEEPHANDS, FEET AND
FACEAWAY FROM MOVING PARTS.
TOGUARD AGAINST POSSIBLEPERSON-
2.Start the engine and let it warm up for approxi-
mately 3-5 minutes. Do not adjust the carburetor
when theengine is cold. Be sure to perform the
carburetor adjustments while in an area that is
wh
AN I
NO
poi
Hig
tothe average outdoortemperatureat
the trimmer will be used.
CAUTION; DONOTRUN THE TRIMMER
ORS WITHOUT ADEQUATEVENTILA-
EXHAUST FUMES ARE POISONOUS
COULDBE DEADLY IF INHALED.
If the engine will not start or if the refer-
setting islost, set both screws so the arrows
to "5%". Lownumbersettingsare lean.
number settings are rich.(Fig. 11).
Figure 11
5

MAINTENANCE PROCEDURES
3. AdjustIdleFirst: With engineidling,rotatethe
Low Speed Screw (L)for the leanest fuel mixture
that allows stable idle, and acceleration without
hesitation.
4. If necessary, idle speed canbeincreasedby
turning the idlestop screw clockwise(Fig. 12).
2. Low Speed Screw (L) (Fig. 13) Close the screw
by gently rotating it clockwise untilalight seating
resistance is felt. Next, rotate the screw 11/4-11/2
turns counterclockwise.
3. Idle Screw(Fig. 13) Close the screw by rotating
it clockwise until the screw contacts the throttle
leverAftercontactis made, continueturning
screw 11/2-21/2 additional turns.
Figure 12
5. Holdthethrottletriggeratthemaximum speed
position and adjust the HighSpeed Screw (H) for
maximum enginespeed.
6. Recheck the idle adjustment.
CARBURETORADJUSTMENTMODELS TC-
300, TC-400 WITH WALBRO CARBURETOR
IMPORTANT: Do not close the carburetor adjusting
screws too tightlyas damageto thescrews andseats
may result. Also, the correct amountof line mustbe
fedfromthetrimmer spoolbeforeadjustingthe
carburetor to ensure that the engine is adjusted for
operation while under load.
1. HighSpeed Screw(H) (Fig. 13) Closethe screw
by gently rotating it clockwise untila light seating
resistance is felt.Next, rotate the screwone turn
counterclockwise.
Figure 13
NOTE: Although these settingsare approximate,
the should be able to be started. Further
adjustments of the carburetor may be necessary
toobtainthe bestperformanceforyour area.
Steps 4-6 shouldbefollowed tofinetunethe
carburetor. Whenmakingtheseadjustments,
turn the screws 1/8 of aturn atatime and wait for
the 'engine to respondto thechange.
6

MAINTENANCE PROCEDURES
4. Start the engine and let it warm up for approxi-
mately 3-5 minutes. Do not adjust the carburetor
when the engineis cold. The adjustments should
be made at thetemperatures that thetrimmer
will beused. Allow the engine toidle. If neces-
sary, re-adjust the idlespeed to keep the engine
fromstalling (3000-3500 RPM onthe TC400,
3000-4500on theTC300)
CAUTION: DONOTRUNTHE TRIMMER
INDOORS WITHOUT ADEQUATE VENTILA-
TION.EXHAUST FUMES ARE POISONOUS
AND COULD BE DEADLY IF INHALED.
5. With' theengine idling, slowly turn the lowspeed
screw clockwise and note the position at which
theenginebeginstoslowdown.Nowturn the
screw counterclockwise and again note the posi-
tion when the engine speed is reduced. Set the
screw at a pointmidwaybetweenthese two
positions.
6. Hold the throttle wideopen and follow the same
procedure toset the highspeed screw.
7. Re-checkthe idle adjustment.
8. Install the air cleanercover.
TROUBLESHOOTING AND
TESTPROCEDURES
Generally, allgasoline-poweredproductsrequire
some form of service or repair during their lifetime.
The amount of time andexpense involved in repair-
ing a product canbe greatly impactedby the amount
of timerequiredtoinitiallydeterminethe cause of
the difficulty. Therefore, it is recommended tomake
these preliminary checks before proceeding to sec-
ondary troubleshootingprocedures.
Preliminary Checks
1. Check for ignition:
a. Check the start/stop switch position
2. Check the spark plug:(refertospecifications.
Page 3)
a. To ensure the correcttype
b. For damage to the insulator
c. For excessive carbon or burnt electrodes
d. For the correctgap
e. Check for spark (refer to page 8)
3. Check the fuel supply:
a. Check the choke position
b. Check the conditionof the fuel, for freshness,
cleanliness, and proper mixture
4. Check the air cleaner: (refer topage 4)
a.For loose or damaged mounting screws
b.For dirtyfilterelements
c. For excessiveoil in the foam element
5. Check cylindercompression(referto page 7)
Testing Cylinder Compression
A compression test of the engine can provide vital
information on the general conditionof the working
parts within the engine. Thistest will indicate a worn
cylinder,piston, or ringandgenerallydetermine
whether theengineissound or if it should be
replaced,.
Compression Test Procedure
1. Install the compressiongauge into the sparkplug
hole.:IMPORTANT: Becertain that nomorethan a
1/2” of the gauge is threaded into the cylinderas
damage to the pistonmay result (Fig. 14).
Figure 14
Compressiontesting
2. Pull the starterropeseveral times to obtain the
highest possible compression reading.
3. If the compression reading is below 100 psi (689
kPa), cylinder, piston, or ring damage should be
suspected If so damaged, a new engine short-
block /shouldbe installed.
7

TROUBLESHOOTING AND
TESTPROCEDURES
Checking for Spark
1. Pull off the spark plug cap and remove the spark
Plug.
2. Inspect thespark plug for wear, carbon deposits
and damage. Replace the plug ifdamaged, burnt
or fouled.
3. Check for the correctspark pluggap and adjust if
necessaryto .020-.024 in (5.6 mm) by bending
outer electrode.
NOTE: Do notpryagainstinnerelectrode.This
could crack the insulator.
4. Attacha spark or ignitiontester as shown in
5. Whilemaintainingtheplug in this position, pull
Figures15or 16.
the starter-rope andobserve for spark.
CAUTION: DO NOTTESTFORSPARK
ERE GASOLINE HAS BEENSPILLED OR
MABLE VAPORS MAY EXIST. A FIRE
NOTE: The sparkmaybedifficult tosee in daylight
or other brightly illuminatedareas.
6. If nospark is seen, refer to the troubleshooting
chart onpage 9.
Figure 15
Spark tester
Toro P/N 41-7890
Figure 16
Alternate type spark tester
Checking Fuel Tank Venting
Thefuel tankcap vent allows air into the tankas fuel
is consumed.If this vent isblocked with dust or dirt,
the engine will eventuallystall.
1. Removethe fuel tankcap and inspectthe vent.If
the cap is contaminated withdirt particles, the
vent may needto be replaced.
2. The capcanbedisassembledby prying up the
insertwith a flatscrewdriver. Care shouldbe
usedtoprevent damage to the insertandthe
valve (Fig-17).
Figure 17
3. Remove the valve, squeeze the valve to close it,
release it, and hold it up to a light. No light should
be visible through thevalve. If light canbe seen,
the~valve shouldbe cleanedor replaced.
4. Withtheinsert removed, holdthe capup to a
light. Light shouldbe visible through a small hole
at the center of the cap. if no light canbe seen,
the' hole should be cleaned.
Checking fuel tank
1. Visually inspect the bottomof the fuel tankfor dirt
or other contaminants.
2. If dirt, water, or other contaminants are present,
the ;tankshould be flushed with a small amountof
fuel, and refilled with freshfuel.
I
Checking the StopSwitch
The “off” switch used on the Toro 1500. 300, and
400 Gas Trimmershasoneset of contactpoints.
When the switch is in the "off"position, the contacts
areclosed, grounding the coil current to the engine.
A continuity testeror ohmmeter is used tocheck for
continuity Note: If an ohmmeter is used.the dial
should,be adjusted to a low setting. Attach the two
tester(leads tothetwoswitchleads.Continuity
should beevident withtheswitchinthe"off"
position. In the "on"positionthereshouldbeno
continuity If continuity is intermittentor notevident,
the switch is defective or a short has developed in
the wiringandtheswitchandharnessshould be
replaced.
a

TROUBLESHOOTINGSHOOTING
AND
TEST PROCEDURES

DISASSEMBLY, REPAIR,
REASSEMBLY INSTRUCTIONS
Trimmer EngineRemoval, Disassembly,
Replacement
1. Drainthe gas fromthetrimmer gas tankand
remove the spark plug high tension wire.
2. Removethe air cleaner cover bypressing up on
thebottom of the cover to releasethelower
mountingtab, and pressing in on the front of the
cover to release the upper tab.
3. Withthetrimmeronitsleft side, remove the
nine Phillips head screws which attach thecase
halves together. NOTE:A service fixture, plans
forwhichare described in GasolineTrimmer
Service BulletinNo.81-05,is very usefulfor
supportingthetrimmerfor disassembly and
reassembly.
4. Removethe right handcase half bylifting it from
thelefthand case half. The case halfmay
appearto be stuck to the engine due to the fitof
the rubber engine isolation mounts between the
case andthe enginebacking plate.NOTE:When
reassembling,installtherubberisolation
mounts in the case halves rather than on the
enginebacking plate.
5. Remove theengine housing tubeandrecoil
starter assembly bytippingtheenginetothe
rear and lifting the tube and starter from the left
handcase half.
6. IMPORTANT: Note howthefuel line, throttle
lever, throttlelink,spring,switch,andwiring
harness arerouted andattached (Fig. 18).
Engine
Mounting Block
7.
Figure 18
Removethegas line from thecarburetor inletby
compressing and sliding the fuel line clamp up
onto the fuel line and twisting and pulling on the
fuel line.
10
8. Removethe throttle and switch,assemblies and
Iift, the engine from the LeftHand Case.
I
clip.
9. Remove the air cleaner elements and retaining
10, Removethe carburetor by removing the Phillips
head screws whichpassthrough the spitback/
choke assembly and carburetor.
11. Remove the cooling shroud halves by removing
the three screws which attach the shroud to the
backing plate, and gently prying open the latch
next to the spark plug wire. NOTE:The TC300
and TC400have a single piece cooling shroud.
12. Remove theflywheel by retainingthestarter
cup with the starter cup wrench P/N45-1390)
and removing the flywheel nut (Fig.24,p. 17).
Use thehandleofthestartercupwrenchto
separate the flywheel from thecrankshaft taper.
The two holes cast into the flywheel shouldbe
tapped with a l/4"-20 tap, and two1/4”-20 x 3/4”
long capscrews used to apply pressure against
the: crankshaft end until the seat between the
flywheel andcrankshaft is loosened.
CAPTION: DO NOT attempt to pry the flywheel
from thecrankshaft or tap on thecrankshaft end
to loosen the flywheel.The crankshaft is made
upof threeparts, with thecrankshaft ends being
pressed onto the crankpin. Pryingor striking the
crankshaft canresult in damagethat will require
replacement of the shortblock.
13. Remove the CDI (Ignition) Module by removing
the' twoscrews which attach the laminations to
the' cylinderassembly.
14. Removethebacking plateassembly by removing
thethreeboltsandtwoPhillips headscrews
which pass through thebacking plate andback-
ing'plate stress plate into the cylinderassembly.
NOTE(TC1500 only):The intakegasket issealed
with a light coating of gasket sealant, and the
backing platemay appear tobestucktothe
cylinder assembly.
15. Removethecrankcase pad bysqueezing the end
of thecrankcase pad clip so that it canbepassed
through the hole in the crankcase.
16. Removethe heat shield and mufflerbyremoving
the' twohex socket capscrews and the Phillips
head screw to the heat shield tab.The tab can
then beremoved by removing the Phillipshead
w that fastens it to thecylinder assembly.

DISASSEMBLY,REPAIR,
REASSEMBLY
INSTRUCTIONS
Figure
19

Starter Rope Replacement
1. Follow steps 1-5 of Trimmer & EngineDisas-
sembly/AssemblyInstructions. NOTE: Do not
removethe Recoil StarterAssembly fromthe
Upper Shaft HousingTube.
2. Removethe damaged ropefrom thepulley.
3. Knot one endof the replacement rope. Align the
cut-outsections of theDrum and themetal
Ratchet Cover.Feed theun-knottedend of the
rope through the clearance hole and into therope
groove in the Drum (Figure 20).
Figure 20
4. a. TC 1500,TC300, TC400
Wind therope clockwise onto the drum, slipp-
ing the rope under the four retainer tabs (do
not wind the drum) until the handle is within 2
inchesfromtheDrum.Continue by rotating
theDrumandslidingthe ropeunderthere-
tainer tabs until therope extendsthrough the
widest gap betweenthe rope retainer tabs.
Install therope bushing and handle.
b. TC400(step 4a or 4b will apply depending
upon the styleof the starter drum)
Wind the rope clockwise onto the drum, slip-
ping the rope betweentheretainerandthe
drum until 2 inches of roperemains.Thread
the end of the roperemainingthroughthe
guideslot in theretainer.Install the rope
bushing and handle.
5. IMPORTANT:Check the starter for proper assem-
bly by extending the starter ropefull length. With
the ropeextended, the starter pulley mustbeable
to be rotated an additional 1/2 turn in a clockwise
direction but not more than 11/2 turns.
Instructions(page IO).
6. To reassemble reversesteps 1-5 in Disassembly
Starter Assembly Replacement.
1. Followsteps 1-5 of Trimmer & EngineDisas-
Instructions.
2. Remove the Recoil StarterAssemblyfromthe
Upper ShaftHousing Tube. Retain the tube by
passing abar through the holes in the tube. Twist
the Recoil Starter Assembly to remove.
3. Press the replacement Recoil StarterAssembly
into: theUpper Shaft Housing Tube. The slots in
the Recoil Starter Assembly which are retained
by the Trimmer case halves must be in line with
the locating holesin the tube, and the widestgap
between roperetainer tabs on the Starter must
be rotated 180° from the Pole Clamp slot cut in
thetube. NOTE: Press onlyontheend of the
Recoil Starter Assembly.
4. IMPORTANT: Check thestarterfor properas-
sembly by extending the starter ropefull length.
With the rope extended, the starterpulleymust
be able to be rotated and additional 1/2 turn in a
clockwisedirection. If theStarterDrum stops
rotating before the rope is extended full length,
remove one wrapof the StarterRope bysliding it
from under the rope retainer tabs andrepeat test
procedure.Ifmorethan 11/2 turnsare possible,
wrap one moreturn on thestarter.
5. To reassemblereverse steps 1-5 in Disassembly
Instructions)page 10).

DISASSEMBLY,REPAIR,
REASSEMBLY INSTRUCTIONS
WALBROCARBURETOROPERATION
Alternate fuel pumpsystem to accom-
modate internal pulseand/or external fuel
source.
1. EngineImpulse:ActuatesFuelPumpDiaphragm with 13. Idletake-Off: FuelentryforIdle holes.
alternating pressure-vacuum pulses.
14. Idle Port: Fuel reservoirfor Idleholes.
2. Fuel Pump Diaphragm:Fluctuates in response to engine
impulse. Transfersfuel throughFuel PumpValves.
15. AtmosphericVent:Allows airpressureagainst Metering
Diaphragm.
3. Fuel Inlet: Fuel drawnfromtank.
4. Inlet Valve:Responds to FuelPumpDiaphgram.Opens
during vacuum pulse. Closes during pressure pulse.
5. OutletValve: Closes during vacuum pulse. Opens during
pressure pulse.
6. Filter Screen: Filtersfuel on routetoMeteringChamber.
7. Inlet Needle Valve: Lifts off seat to allow fuel entry into
MeteringChamber.
8. Throttle Valve: Regulates engine speed as it exposes Pri-
mary. Second, and Third Idle holes, then Nozzle for fuel
delivery.
9. PrimaryIdle Hole:Only fuel source to engine atIdle
position.
10. Second IdleHole: Allows additional fuel flow onaccelera-
tion.
16. Circuit Plate: Meters fuel from MeteringChamber to Low
Speed and High Speed Circuits.
Metering Lever.
17. MeteringDiaphragm:Drawnupbyvacuum to activate
18. MeteringLever: Lifts InletNeedle off seat.
19. MeteringLever Spring: Transmits forceto MeteringLever.
Closes Needle Valveas MeteringChamber fills.
20. MeteringChamber: Fuel reservoir, feedsto Idleand Nozzle
circuits.
21. Nozzle CheckValve: Engine vacuum draws Valve open.
22, Nozzle Well: Fuel is drawn in from Metering Chamber at
highspeed
23. HiSpeed Needle: Adjustsfor fuelrichnessat highspeeds.
24. Nozzle Increasesfuel discharge for highspeeds.
11. Third IdleHole: Increasesfuel flow atPart Throttle.
12. IdleNeedle:Adjust for fuelrichnessto 3 Idleholes.
25. Venturi: Increases airvelocity atNozzle, creating a suction
to draw fuel into ThrottleBore.
13

DISASSEMBLY,REPAIR,
REASSEMBLY INSTRUCTIONS
WALBROCARBURETOR SERVICING
-Metering DiaphragmCover
MeteringLever
Inlet Needle
-Metering Diaphragm Assembly
Metering Diaphragm Gasket
V
Circuit PlateAssembly
Circuit PlateGasket
Circuit Check Valve
Throttle Valve Screw
Throttle Valve
,IdleNeedle
HiSpeed Needle
FuelInlet Screen Throttle ShaftAssembly
Fuel PumpDiaphragm
Fuel Pump Gasket
Fuel PumpCover
Idle Adjust Screw
Figure 22
Carburetor Disassembly (Refer to Fig. 22):
1. Remove thefuelpump cover screwandpump 8. Removethemeteringdiaphragmand gasket.
9. Inspect themeteringdiaphragmfor holes, dirt
2. Removethefuelpump diaphragmand fuelpumpandforeignmatter.
10. Remove the metering lever screw and metering
3. Inspectthediaphragmforflatnessandcontinu-levercomponentsincluding lever, pin,needle
11. Remove thecircuitplatescrewwiththedia-
cover.
gasket.
ity. Thediaphragmshouldhave no holes. Thevalve andspring.
flappervalvesshould be flatandfree,from
curling. phragm andgasket.
4. Blowthroughtheexternalpulseholeonthe
bodycasting toinsurethatthereareno ob-
structions.
12. Remove thehighandlow speed adjustment
needle
5. Blow through the internal fuel hole on thebody
casting to insure that there are no obstructions.
13.Thoroughlyinspectandcleanthecarburetor,
especially all small orifices andopenings, using
a solventwash and an air gun.
6. Remove and discardthe filter screen.
7. Remove thefourscrewsandmeteringdia-operation of thethrottle valve andlever.
!
14.Drythecarburetorwithairand inspect the
phragm plate.
14

DISASSEMBLY, REPAIR,
REASSEMBLY INSTRU'CTIONS
Carburetor Re-Assembly
1. Install a new filter screen with anyappropriate
hollowtubeortool of approximately ,300 inch
diameter. NOTE: The screen must bepushed in
far enough to be below the fuel inlethole.
2. Inspect the circuit plate for flatness and correct if
3. Inspect thenewcircuitplate diaphragmand
gasket for flatness. Install the circuitplate, circuit
diaphragmandcircuitplate gasket with dia-
phragm in contact with the plate and gasket in
contact with body casting. Use only moderate
pressure on the circuit plate screw so as not to
warp the circuit plate.
4. Install the meteringlever components and adjust
the meteringlever to beflush with the surface of
the circuitplate, Fig. 23.
necessary.
5. Install the high and lowspeed needles and setat
approximately 1 and 1/4 turns open. The high and
lowspeed letters are indicated on theside of the
carburetor casting. The high speed needle is the
longneedleand the lowspeed needle is the short
needle.
6. Install the metering diaphragm and related com-
ponents as follows:Installthe gasket over the
locatorpins onthe casting. Next, installthe
metering diaphragm over the locator pins on the
casting. (The metering plate pin mustbe in con-
tact with themetering lever.)Next, installthe
metering diaphragmcover with four screws. The
vent hole in the cover shouldbe located opposite
the throttlevalve.
7. With the large singlescrew, install the fuel pump
cover with the fuel pumpdiaphragm in contact
with the body casting and with the fuel pump
gasket in contact with the fuel pump cover. The
extension on thecover should be locatedon the
same side asthe throttle lever.
8. Visuallyinspectthe carburetor andtightenall
screws.
Figure 23
15

of
Difficulty
Reduced cutting
ability
Cutting line fails
to advance
Cuttingline pulls
back into drum
(or
tangles)
Line
spool fails
to turn
TROUBLESHOOTING AND
TESTPROCEDURES
CUTTERHEADTROUBLESHOOTING
RPM too low
Clutch fails to
engage
Clutchfails
to
disengage at idle
speed
RPM too high
Binding
Not seated
in
engine or
cutting unit
Notseated in
engine
or
cutting unit
I
Bearing seized
Cutting line Clutch slipping
too short,
won't index
Driver broken,'
lineswelled
from moisture,
dirty, line
I
tangled
Cutting line not
indexed often
enough
or prior
to engine shut
Off
Driver or drum Bearing grease
broken on clutch drum
Power shaft
snap ring out
of
groove (some
models), clutch
spring broken
Unbalanced
cutting unit,
bearings worn,
dirt
accumulation
Incorrect
assembly
Incorrect
assembly
I
16

i
DISASSEMBLY, REPAIR,
REASSEMBLY INSTRUCTIONS
CLUTCH REPAIR
The clutchconsists of twoassemblies: (Fig.24):
A. The upper housingcontainingthe upper power
shaft,ballbearing,oil shield, clutch spacer,
clutch assembly and
B. The lowerbearinghousingandclutchdrum
which isthreaded to the lower housing shaft.
NOTE: The oilshieldwasnot used in early
production of the TC-400 clutch assembly. Also,
the upper powershaft with the snap ringwas
changed to a machinedshaft with a shoulder.
The two shafts are interchangeable. The oil
shieldmay be added toexistingclutch assem-
bliesusingthe upper shaft with themachined
ring.
Disassembly & Assembly instructions
1. Remove the cutterhead or linefeed assembly.
2. Remove theclutchhousingfromthetrimmer
tube by looseningthe housing clamp bolt.
3. Remove thesixscrewssecuringthe upper and
lower sections of theclutchhousing. Separate
the twosections by gently prying themapart.
4. The clutch assembly (shoes and springs) can be
1390 (Fig 25). Align the pins on the tool with the
holes in theclutch assembly. While supporting
the opposite end of the power shaft with a piece
removed with themultipurposetool P/N #45-
of 3/16 inch squarekey stock, turntheclutch
assembly counterclockwise. The spacer,oil shield
and power shaft can now beremoved.
Clutch Wrench
Figure 25
Multipurpose tool(P/N 45-1 390)
NOTE; When reassembling the clutch shoe and
spring assembly, besure that the sidemarked
"off" is toward you. The wideflangeonthe
spacer mustbeagainsttheclutch shoeand
springassembly.
5. Remove the three screws in the bearing retainer.
The bearing fits loosely and can be pushed out by
gently tapping the bearing from the topor clamp
end of the housing.
6. The shaft andbearings in the lower clutch hous-
ing are notserviceable as individual components
and mustbe replaced as anassembly.
17