YAMAHA JOG Diagram

1987 - 1990

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MOTORCYCLE

SERVICE MANUAL

Model : CE50T, CG50A, CG50U, CG50W

2YT281972000

*2YT281972000*

CE50T

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SERVICE MANUAL

©1986 by Yamaha Motor Co., Ltd.

1st Edition, November 1986

All rights reserved. Any reprinting or

unauthorized use without the written

permission of Yamaha Motor Co., Ltd.

is expressly prohibited.

3

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NOTICE

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This manual was written by the Yamaha Motor Company primarily for use by Yamaha dealers and
their qualified mechanics. It is not possible to put an entire mechanic's education into one manual,

so it is assumed that persons using this book to perform maintenance and repairs on Yamaha scooter
have a basic understanding of the mechanical concepts and procedures inherent in scooter repair tech-
nology. Without: such knowledge, attempted repairs or service to this model may render it unfit to

use and/or unsafe.
Yamaha Motor Company, Ltd. is continually striving to improve all models manufactured by Yamaha.

Modifications and significant changes in specifications or procedures will be forwarded to all Autho-
rized Yamaha dealers and will, where applicable, appear in future editions of this manual.

TECHNICAL PUBLICATIONS

SERVICE DIVISION

MOTORCYCLES OPERATIONS

YAMAHA MOTOR CO., LTD.

HOW TO USE THiS MANUAL

PARTICULARLY iMPORTANT iNFORMATiON

This material is distinguished by the following notation.

D

NOTE: A NOTE provides key information to make procedureseasier or clearer.

ili ii i iiil ACAUTIONindicatesspecialproceduresthatmustbefollowedtoavoid

damage to the scooter.

A WARNING indicatesspecial procedures that must be followed to avoid injury
to a scooter operator or person inspecting or repairingthe scooter.

MANUAL FORMAT

All of the procedures in this manual are organized in a sequential, step-by-step format. The informa-
tion has been compiled to provide the mechanic with an easy to read, handy reference that contains
comprehensive explanations of all disassembly, repair, assembly, and inspection operations.

In this revised format, the condition of afaulty component will precede an arrow symbol and the course
of action required will follow the symbol, e.g.,

• Bearings
Pitting/Damage_ Replace.

EXPLODED DIAGRAM

Each chapter provides exploded diagrams before each disassembly section for ease in identifying cor-
rect disassembly and assembly procedures.

(9 ® iLLUSTRATED SYMBOLS

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IGENINFO (Refer to the illustration)

Illustrated symbols (_) to _) are designed as
thumb tabs to indicate the chapter's number and

(_ (_) content.

ENG OOL Periodic inspection and adjustment

(_ (_) _ Carburetion

ICARB[ ]_ 1 _"AS1_I _(_)_; pter'nCdl'ces

® ®

® ® _ Illustrated symbols (_ to (_) are used to identify

%_JDI IC _i General information

_ EngineCooling system

Chassis

@

6_ _ the specifications appearing in the text.

(_) Filling fluid
(_ Lubricant

(_) Tightening

_Wear limit, clearance(_) (_) -- Engine speed

@ @

® ®

.,1 _ j diagram indicate grade of lubricant and location

- _ = of lubrication point.
_ _ ® Apply engine o,1

@ (_ (_ @(_Apply molybdenum disulfide oilApply wheel bearing grease

_ _ _ _L_.._ _(_))Apply lightweight lithium-soap base grease

@

Illustrated symbols (_ to (_ in the exploded

® Apply gear oil

Apply molybdenum disulfide grease
Apply locking agent (LOCTITE ®)

®

l

m

i

INDEX

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GENERAL,NFORMAT,ON

ENGINE OVERHAUL '_'%_

ENG _

CARBURETION

CARB_,

CHASSIS CHAS_

L..,-.-----J

ELECTRICAL ELEC_

APPENDICES APPX_

i

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!

i

i

1

p,

GEN

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CHAPTER 1

GENERAL INFORMATNON

SCOOTER IDENTIFICATION ....................................... B-3

VEHICLE IDENTIFICATION NUMBER .............................. B-3

ENGINE SERIAL NUMBER ....................................... B-3

IMPORTANT INFORMATION ...................................... B-3

ALl. REPLACEMENT PARTS ..................................... B-3

GASKETS, OIL SEALS, AND O-RINGS ............................ B-3

LOCK WASHER/PLATES AND COTTER PINS ..................... B-3

BEARINGS AND OIL SEALS ..................................... B-4

CIRCLIPS ...................................................... B-4

SPECIAL TOOLS .................................................. B-4

FOR TUNE-UP .................................................. B-4

FOR ENGINE SERVICE .......................................... B-4

FOR CHASSIS SERVICE ......................................... B-5

FOR ELECTRICAL COMPONENTS ................................ B-5

m

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INFO

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SCOOTER IDENTIFICATION

GENERAL

INFORMATION

SCOOTER IDENTIFICATION

VEHICLE IDENTIFICATION NUMBER

The vehicle identification number (~ is stamped
into the frame.

NOTE:

The vehicle identification number is used to iden-
tify your scooter and may be used to register your
scooter with the licensing outhority in your state.

Starting Serial Number:

JYA2U G00-~ H A720101

ENGINE SERIAL NUMBER

The engine serial number (~ is stamped into the
crankcase.

NOTE:

The first three digits of these numbers are for

model identifications; the remaining digits are the
unit production number.

Starting Serial Number:

14T-720101

NOTE:

Designs and specifications are subject to change

without notice.

1-1

IMPORTANT INFORMATION INFO

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I°E"

IMPORTANT INFORMATION

ALL REPLACEMENT PARTS

1. Use only genuine Yamaha parts for all
replacements. Use oiland/or grease recom-

mended by Yamaha for assembly and adjust-

ment. Other brands may be similar in func-
tion and appearance, but inferior in quality.

GASKETS, OIL SEALS, AND O-RINGS

1. All gaskets, seals, and O-rings should be
replaced when an engine is overhauled. All

gasket surfaces, oil seal lips and O-rings must
be cleaned.

2. Properly oil all mating parts and bearings dur-

ing reassembly. Apply grease to the oil seal
lips.

LOCK WASHERS/PLATES AND COTTER
PINS

must be replaced when they are removed.

Lock tab(s) should be bent along the bolt or
nut flat(s) after the bolt or nut has been pro-
perly tightened.

1. All lock washers/Plates (_ and cotter pins

1-2

INFO iMPORTANT iNFORMATiON

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BEARINGS AND OIL SEALS

manufacturer's marks or numbers facing out-
ward. (In other words, the stamped letters

__) _ must be on the side exposed to view.) When

(_ ings dry. This causes damage to the bearing

_/._/7_/_////_ When installing a cirelip (_, make sure th at

/J sectional view.

installing oil seal(s), apply a light coating of

i. Install the bearing(s) and oil seal(s) with their

lip(s). Oil the bearings liberally when installing.
light-weight lithium base grease to the seal

(_ Oil seal

Do not use compressed air to spin the bear-

surfaces.

(_ Bearing
CIRCLIPS

1. All circlips should be inspected carefully

clips after one use. Replace distorted circlips.

e orereas ereoaceO ton

the sharp edged corner (_ is positioned op-

posite to the thrust (_) it receives. See the

(_) (_) Shaft

1-3

3

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GEN

I

SPECIAL TOOLS I
SPECIAL TOOLS

The proper special tools are necessary for com-
plete and accurate tune-up and assembly. Using
the correct special tool will help prevent damage
caused by the use of improper tools or improvis-
ed techniques.

FOR TUNE-UP

1. Inductive Tachometer
P/N. YU-08036

This tool is needed for detecting engine rpm.

2. Compression Gauge
P/N. YU-33223

This gauge is used to measure engine compr-
ession.

FOR ENGINE SERVICE

1. Flywheel Holding Tool
P/N. YU-01235

This tool is used to the hold the flywheel magneto

and clutch assembly when removing or installing
the securing nut.

2. Flywheel Magneto Puller

P/N.

YM-01189

This tool is used to remove the flywheel.

1-4

I GEN

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SPECIAL TOOLS

i ............. ir

3. Primary Sheave Holder

P/N.

YS-01880

This tool is used when holding the clutch hub.

4. Clutch Spring Holder

P/N.

YS-28891
This tool is used to disassembly and assembly the
secondary sheave.

P

5.

Thickness Gauge
P/N. YU-03001

6.

Universal Puller Set

P/N. YU-33270

This tool is used to remove the crankshaft from
the crankcase.

7. Crankcase Separating Tool
P/N. YU-01135

This tool is used to remove the crankshaft or
separate the crankcase.

1-5

I

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GEN

SPECIAL TOOLS I

8. Crankshaft Installation Set

P/N. YU-90050 ...................... (~)

Adapter (M10)

P/N. YM-90062 ..................... (~

Adapter (M12)

P/N. YM-90063 ..................... ~)

These tools are used to install the crankshaft.

9. Sealant (Quick Gasket ~)
P/N. ACC-11001-05-01

This sealant (bond) is used for crankcase mating
surfaces.

,.Fol l

@

!J

FOR CHASSIS SERVICE

1. Ring Nut Wrench
P/N. YU-01268 (~

P/N. YU-33975 ..................... (~

This tool is used to loosen and tighten the steer-
ing ring nut.

FOR ELECTRICAL COMPONENTS

1. Pocket Tester
P/N. YU-03112

This instrument is invaluable for electrical system

inspection and §djustment.

2. Electro Tester
P/N. YU-33260

This instrument is necessary for ignition system

inspection.

1-6

INSP

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CHAPTER 2

PERiODiC iNSPECTiONS AND ADJUSTMENTS

INTRODUCTION ................................................. C-3

PERIODIC MAINTENANCE/LUBRICATION INTERVALS ............ C-3

TAIL COVER ..................................................... C-3

REMOVAL .................................................... C-3

INSTALLATION ................................................ C-4

FRONT FENDER, FRONT PANEL AND FOOTREST BOARD ......... C-4

REMOVAL .................................................... C-4

INSTALLATION ................................................ C°5

HANDLEBAR COVERS ........................................... C-5

REMOVAL ..................................................... C-5

INSTALLATION ................................................ C-5

ENGINE .......................................................... C-5

ENGINE IDLE SPEED ADJUSTMENT ............................. C-5

THROTTLE CABLE FREE PLAY ADJUSTMENT ................... C-6

AUTOLUBE PUMP CABLE ADJUSTMENT ........................ C-6

AUTOLUBE PUMP AIR BLEEDING ............................... C°7

AIR CLEANER ELEMENT CLEANING ............................. C-8

FUEL COCK CLEANING ........................................ C-8

COMPRESSION PRESSURE MEASUREMENT ..................... C-9

ENGINE OIL LEVEL INSPECTION ................................ C-10

TRANSMISSION OIL REPLACEMENT .... ........................ C-10

FUEL LINE INSPECTION ........................................ C-11

CHASSIS ........................................................ C-11

FRONT BRAKE LEVER FREE PLAY CHECK ....................... C-11

REAR BRAKE LEVER FREE PLAY CHECK ....................... C-11

FRONT AND REAR BRAKE LINING INSPECTION ................ C-12

TIRE AND WHEEL INSPECTION ................................. C-12

STEERING ADJUSTMENT ...................................... C-12

ELECTRICAL ..................................................... C-13

BATTERY ..................................................... C-13

FUSE INSPECTION ............................................. C-14

SPARK PLUG INSPECTION ..................................... C-14

HEADLIGHT BEAM ADJUSTMENT .............................. C-15

IGNITION TIMING ......................................... ..... C-15

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ADJ LUBRICATION iNTERVALS

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I INSPli 1 INTRODUCTION/PERIODIC MAINTENANCE/ B

PERIODIC INSPECTIONS AND ADJUSTMENTS

INTRODUCTION

This chapter includes all information necessary to perform recommended inspections and adjustments.
These preventiw, • maintenance procedures, if followed, will ensure more reliable vehicle operation and

a longer service life. The need for costly overhaul work will be greatly reduced. This information ap-
plies to vehicles already in service as well as new vehicles that are being prepared for sale. All service

technicians should be familiar with this entire chapter.

PERIODIC MAINTENANCE/LUBRICATION INTERVALS

Unit: km (mi)

BREAK-IN

ITEM REMARKS 500 3,000 6,000

(300) (2,000) or (4,000) or

Spark plug Check/Clean or replace. O © O
Air filter Clean. Replace if necessary. O ©
Carburetor Check/Adjust/idle speed, starter operation. © ©

Fuel line Check fuel hose for cracks or damage. O O

Transmission oil Replace (Warm engine before draining). Replace Check Check

Autolube pump Check/Adjust/Air bleeding. O O
Brake Check operation. Adjust if necessary. O O
Wheels* Check balance/damage/runout. O O

Wheel bearings damage. Replace if damaged.

Steering bearing Moderately repack every 12,000 (8,000) Check Check Check

Rear shock absorber Check operation. O O
Fittings/Fasteners Check all chassis fittings and fasteners. O O O

Battery for proper operation.

Every 12,000 (8,000) or 24 months.

Check bearings assembly for looseness/ O O
Check bearings assembly for looseness.

or 24 months.**

Check specific gravity. Check breather pipe O O

EVERY

6 months 12 months

V-belt Check damage and wear. O

**: Medium weight wheel bearing grease.

2-1

Replace if necessary.

TAIL COVER ADJ

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TAIL COVER

REMOVAL

1. Open the seat lock.

2. Remove:
=Seat

3. Remove:

-Cover (_

4. Remove:
,Grab bar

_ , Rear carrier

(With rear flasher lights and taillight)

5. Disconnect:
,Rear flasher light leads

•Taillight leads

6. Remove:

®Side covers (Right and left)

NOTE:
When removing the side cover, unhook it at the

front and slide it forward.

7. Remove:

=Tail cover

: !!

2-2

INSP E

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ADJ _1 TA'LCOVER

INSTALLATION

When installing the tail cover, reverse the

"REMOVAL" procedure.
Note the following points.

1. Install:
®Side covers

NOTE:

After installing the side covers, make sure that

all hooks are securely fitted.

2. Connect:

eRear flasher light leads

NOTE:

The leadsof identical colors should beconnected.

31install:

i_J_. ®Rear carrier
i__i 7Nm (0.7 m,kg, 5.1 ft-lb)

4. Install:
eSeat

!_ 7 Nm (0.7 5.1 ft,lb)

2-3

m,kg,

I FRONT FENDER, FRONT PANEL INSP

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- i

AND FOOTREST BOARD ADJ

FRONT FENDER, FRONT PANEL AND FOOTREST BOARD

REMOVAL

1. Remove:

-Tail cover
Refer to "TAIL COVER" section.

2. Remove:
®Front fender

_, NOTE:

@ i:Q::!i hooks are free.

_N % - -_ - 3. Remove:
_iiiii:iiii___" ,Main switch cap

i:iiii!i!ilii_ii Turn the cap counterclockwise.

!_-::

Before removing the fender, make sure that all

4. Remove:
®Front panel

5. Remove:
, Footrest board

2-4

I INSP

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FRONT FENDER, FRONT PANEL

AND FOOTREST BOARD/HANDLEBAR COVERS

I

NSTALLATION

Reverse the "REMOVAL" procedure.
Note the following points,

1. Install:
® Front fender

NOTE:

After installing the front fender, make sure that
all hooks are securely fitted.

E

HANDLEBAR COVERS

REMOVAL

1. Remove:
=Screws (Handlebar cover -- Front)
=Rear view mirror(s)

2. Disconnect:

-Headlight lead and flasher light leads

3. Remove:

-Handlebar cover (Front) (~

4. Disconnect:
® Leads

-Speedometer cable (~

5. Remove:
®Handlebar cover (Rear) (~

2-5

ENGINE iDLE SPEED ADJUSTMENT I ADJ

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INSTALLATION

1. Install:
oHandlebar cover (Rear) (~)

2. Connect:

• Leads
oSpeedometer cable (~)

NOTE:

Position the cables as shown.

Front brake cable
(~) Throttle cable
(~) Rear brake cable

I

3. Connect:
eHeadlight lead and flasher ]~ght leads

4. Install:
® Handlebar cover (Front)
®Rear view mirror(s)

ENGINE

ENGINE iDLE SPEED ADJUSTMENT

1. Remove:

• Tail cover,.

Refer to "TAIL COVER" section.

2. Start the engine and warm it up before check-
ing the idle speed.

NOTE:

A warm engine is defined as one which had been
operated for about 3 minutes at 3,000 r/min with
no load.

2-6

I INSP

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ENGINE IDLE SPEED ADJUSTMENT/

THROTTLE CABLE FREE PLAY ADJUSTMENT

3. Attach:
®Inductive Tachometer (YU-08036)

4. Check:
eEngine idle speed

Out of specification-*Adjust.

Engine Idle Speed:

1,500-2,100 r/rnin

Engine idle speed adjustment steps;
®Start the engine at idle speed.

eTurn the throttle stop screw (~ clockwise to

increase engine speed and counterclockwise
to decrease engine speed.

E

5. Install:
eTail cover

Refer to "TAIL COVER" section.

THROTTLE CABLE FREE PLAY

ADJUSTMENT

1. Check:
*Throttle cable free play (~

Out of specification-*Adjust.

[~ Throttle Cable Free Play (~):

3.0-7.0 mm (0.12-0.28 in)

Throttle cable free play adjustment steps;

NOTE:

Before adjusting the throttle cable free play,

the engine idle speed should be adjusted.

2-7

AUTOLUBE PUMP CABLE ADJUSTMENT ADJ

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=Loosen the Iocknut (_.
oTurn the adjuster (_ in or out until the cor-

!_:__...... rect free play is obtained.

=Tighten the Iocknut.

AUTOLUBE PUMP CABLE ADJUSTMENT

NOTE:
Beforeadjustingthe pumpcable, adjustthe throt-

tle cable free play.

1. Remove:
=Tail cover

Refer to "TAIL COVER" section.

* Front fender

=Front panel
eFootrest board

Refer to "FRONT FENDER, FRONT PANEL

AND FOOTREST BOARD" section.

2. Check:

*Throttle cable free play (_

(at carburetor side)
Out of specification_Adjust.

..... 1.0 mm (0.04 in)

J_ Thrott,eCableFreePlay(_):

Throttle cable free play adjustment steps;

=Loosen the Iocknut (_.
=Turn the adjuster _ in or out until the cor-

rect free play is obtained.

=Tighten the Iocknut.

2-8

4. Close the throttle grip completely.

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5. Check:
®Autolube pump pulley position (_

Out of position-*Adjust.

®:

0.0-1.0 mm (0.0-0.04 in)

_ Autolube Pump Pulley Position

Autolube pump pulley position adjustment
steps:

oLoosen the Iocknut _.

®Turnthe adjuster (_ in or out until the pump

plunger pin (_ is aligned with the mark _)
on the pump pully.

eTighten the Iocknut.

6. Install:
oAutolube pump cover

oFootrest board
®Front panel

• Front fender

eTail cover

Refer to "FRONT FENDER, FRONT PANEL

AND FOOTREST BOARD" and "TAIL

COVER" section.

AUTOLUBE PUMP AIR BLEEDING
The Autolube pump and delivery lines must be

bled on the following occasions:

•,Whenever the Autolube tank has run dry.
oWhenever any portion of the Autolube

system is disconnected.

oIf the scooter lieson its sideafter falling over.

2-9

__ AUTOLUBE PUMP AIR BLEEDING ADJ

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1. Remove:
=Tail cover

®Front fender

-Front panel

• Footrest board

Refer to "TAIL COVER" and "FRONT
FENDER, FRONT PANELAND FOOTREST

BOARD" section.

2. Remove:

®Autolube pump cover

J

I,.sPl l

3. Remove:

• Bleed screw @

NOTE:
Place a rag under the Autolube pump.

4. Start the engine at idle speed.

5. Air bleed:
Keep the oil running out until air bubbles

disappear.

NOTE:
Pull the pump cable all the way out to set the

pump stroke to a maximum.

6. Inspect:
®Bleed screw gasket

Damage_Replace.

7. Install:

•,Bleed screw gasket

• Bleed screw

2-10

ADJ AiR CLEANER ELEMENT CLEANING

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t INSP AUTOLUBE PUMP AiR BLEEDING/

8. Keep the enginerunningat about2,000 r/min

for two minutes or so, and both distributor
and delivery pipe can be completely bled.

NOTE:
It is difficult to bleed the distributor completely

with the pump strokeat aminimum, and therefore
the pump stroke should be set to a maximum.

9. Install:
eAutolube pump cover

• Footrest board
®Front panel

Front fender

oTail cover

Refer to "FRONT PANEL, FRONT FENDER

ANT FOOTREST BOARD" and "TAIL

COVER" section.

AIR CLEANER ELEMENT CLEANING

1. Remove:
®Side cover (Left)

;_ NOTE:

When removing the side cover, unhook it at the
front and slide it forward.

2. Remove:
®Air cleaner case cover (_

eAir cleaner element

i i : i_iii i:i i_i!i !_i!i i_ ! i

Never operate the engine with the air cleaner
element removed. This will allow unfiltered

air to enter, causing rapid wear and possi-
ble engine damage. Additionally, operation

without the cleaner element will affect car-

buretor jetting with subsequent poor perfor-
mance and possible engine overheating.

Be careful not to have rags or the like block-
ing the intake area of the air cleaner.

2-11

;'='8 I AiR CLEANER ELEMENT CLEANHNG/ INSP

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FUEL COCK CLEANING ADJ

3. Clean:
oAir cleaner element

Air cleaner element cleaning steps:
oWash the element gently, but thoroughly in

solvent.

Never use low flash point solvents such as
gasoline to clean the element. Such sol-

vent may lead to a fire or explosion.

oSqueezethe excess solvent out of the element

and let dry.

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Do not twist the element when squeezing

the element.

4. Inspect:
oElement

Damage-_ Replace.

5. Apply:
oFoam-air-filter oil or SAE 10W30 type SE

motor oil
Onto the element.

6. Squeeze out the excess oil.

NOTE:
The element should be wet but not dripping.

7. Install:
oAir cleaner element

®Air cleaner case cover
®Side coyer (Left)

FUEL COCK CLEANING

1. Remove:

-Tail cover
Refer to "TAIL COVER" section.

2-12

ADJ FUEL COCK CLEANHNG

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I,NsP E

2. Drain:
=Fuel

FUEL IS HIGHLY FLAMMABLE:

__ _k,_ ®Always turn off the engine when draining.

==_£ or exhaust pipe/muffler when draining.

' =_ { " oNever drain fuel while smoking or in the

(_ *Cap (_

_,_/ (_) ®Filter (_

_*_'!_ii!_iiii_ _:::_ 4. Clean:

=Take care not to spill any fuel on the engine

vicinity of an open flame.

3. Remove:

Filter

oCap

Wash the filter and cap gently using solvent.

2-13

5. Inspect:

• Filter
oO-ring

Damage--* Replace.

6. Install:
®O-ring

Filter

oCap
oTail cover

Refer to "TAIL COVER" section.