YFM350S

3GD-AE7

SUPPLEMENTARY

SERVICE MANUAL

FOREWORD

This Supplementary Service Manual has been prepared to introduce new service and data for the

YFM350S. For complete service information procedures it is necessary to use this Supplementary

Service Manual together with the following manual.

YFM350X(J) ’97 SERVICE MANUAL: 3GD-AE5

YFM350X(P) 2002 SUPPLEMENTARY SERVICE MANUAL: 3GD-AE6

YFM350S

SUPPLEMENTARY

SERVICE MANUAL

©2004 by Yamaha Motor Co., Ltd.

First edition, January 2004

All rights reserved.

Any reproduction or unauthorized use

without the written permission of

Yamaha Motor Co., Ltd.

is expressly prohibited.

EBS00002

NOTICE

This manual was produced by the Yamaha Motor Company primarily for use by Yamaha dealers

and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one

manual, so it is assumed that anyone who uses this book to perform maintenance and repairs on

Yamaha machine has a basic understanding of the mechanical ideas and the procedures of

machine repair. Repairs attempted by anyone without this knowledge are likely to render the

machine unsafe and unfit for use.

Yamaha Motor Company, Ltd. is continually striving to improve all its models. Modifications and sig-

nificant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers

and will appear in future editions of this manual where applicable.

NOTE:

_

Designs and specifications are subject to change without notice.

EBS00003

IMPORTANT INFORMATION

Particularly important information is distinguished in this manual by the following notations.

The Safety Alert Symbol means ATTENTION! BECOME ALERT! YOUR

SAFETY IS INVOLVED!

Failure to follow WARNING instructions could result in severe injury or death

to the machine operator, a bystander or a person checking or repairing the

machine.

A CAUTION indicates special precautions that must be taken to avoid dam-

age to the machine.

A NOTE provides key information to make procedures easier or clearer.

WARNING

CAUTION:

NOTE:

EBS00004

HOW TO USE THIS MANUAL

MANUAL ORGANIZATION

This manual consists of chapters for the main categories of subjects. (See “symbols”)

1st title 1: This is the title of the chapter with its symbol in the upper right corner of each page.

2nd title 2: This title indicates the section of the chapter and only appears on the first page of each

section. It is located in the upper left corner of the page.

3rd title 3: This title indicates a sub-section that is followed by step-by-step procedures accompa-

nied by corresponding illustrations.

EXPLODED DIAGRAMS

To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each

removal and disassembly section.

1. An easy-to-see exploded diagram 4 is provided for removal and disassembly jobs.

2. Numbers 5 are given in the order of the jobs in the exploded diagram. A number that is enclosed

by a circle indicates a disassembly step.

3. An explanation of jobs and notes is presented in an easy-to-read way by the use of symbol marks

6. The meanings of the symbol marks are given on the next page.

4. A job instruction chart 7 accompanies the exploded diagram, providing the order of jobs, names

of parts, notes in jobs, etc.

5. For jobs requiring more information, the step-by-step format supplements 8 are given in addition

to the exploded diagram and the job instruction chart.

EB003000

ILLUSTRATED SYMBOLS

Illustrated symbols 1 to 8 are printed on the

top right of each page and indicate the subject

of each chapter.

1 General information

2 Specifications

3 Periodic checks and adjustments

4 Engine

5 Carburetion

6 Chassis

7 Electrical

8 Troubleshooting

Illustrated symbols 9 to E are used to identify

the specifications appearing in the text.

9 Filling fluid

0 Lubricant

A Special tool

B Torque

C Wear limit, clearance

D Engine speed

E Ω, V, A

Illustrated symbols F to L in the exploded

diagrams indicate the types of lubricants and

lubrication points.

F Apply engine oil

G Apply gear oil

H Apply molybdenum disulfide oil

I Apply wheel bearing grease

J Apply lightweight lithium soap base grease

K Apply molybdenum disulfide grease

L Apply silicon grease

Illustrated symbols M to N in the exploded

diagrams indicate where to apply a locking

agent M and when to install a new part N.

M Apply the locking agent (LOCTITE^®)

N Replace

1

2

3

4

5

6

7

8

9

0

A

B

C

D

E

F

G

H

I

M

N

GEN

INFO

SPEC

CHK

ADJ

ENG

CARB

CHAS

–

+

ELEC

TRBL

SHTG

T R

.

.

E

G

M

B

LS

M

S

J

K

L

LT

New

CONTENTS

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

MACHINE IDENTIFICATION ....................................................................... 1

MODEL LABEL ...................................................................................... 1

SPECIAL TOOLS ......................................................................................... 2

SPECIFICATIONS.............................................................................................. 3

GENERAL SPECIFICATIONS ..................................................................... 3

MAINTENANCE SPECIFICATIONS ............................................................ 5

ENGINE ................................................................................................. 5

CHASSIS ............................................................................................... 7

ELECTRICAL....................................................................................... 10

CABLE ROUTING ...................................................................................... 11

PERIODIC CHECKS AND ADJUSTMENTS.................................................... 23

INTRODUCTION........................................................................................ 23

PERIODIC MAINTENANCE/LUBRICATION.............................................. 23

SEAT, FENDERS AND FUEL TANK.......................................................... 25

SEAT, SIDE COVERS, AND FRONT PANEL ..................................... 25

FOOT PROTECTORS, ENGINE SKID PLATE,

AND FRONT BUMPER....................................................................... 26

HEADLIGHTS AND FRONT FENDER ................................................ 27

REAR FENDER ................................................................................... 28

FUEL TANK ......................................................................................... 30

CHASSIS.................................................................................................... 32

CHECKING THE FRONT BRAKE PADS............................................. 32

ADJUSTING THE PARKING BRAKE .................................................. 32

ADJUSTING THE REAR SHOCK ABSORBER................................... 33

ELECTRICAL SYSTEM.............................................................................. 35

CHECKING AND CHARGING THE BATTERY ................................... 35

ADJUSTING THE HEADLIGHT BEAMS ............................................. 40

REPLACING A HEADLIGHT BULB..................................................... 41

ENGINE ............................................................................................................ 42

ENGINE REMOVAL ................................................................................... 42

INSTALLING THE ENGINE ................................................................. 42

CLUTCH..................................................................................................... 43

INSTALLING THE RIGHT CRANKCASE COVER............................... 43

CARBURETOR................................................................................................. 44

CARBURETOR .......................................................................................... 44

CHASSIS .......................................................................................................... 47

REAR WHEELS AND REAR AXLE HUB................................................... 47

REMOVING THE REAR AXLE ............................................................ 49

INSTALLING THE REAR AXLE........................................................... 50

FRONT ARMS AND FRONT SHOCK ABSORBER ................................... 51

REAR BRAKE ............................................................................................ 53

ASSEMBLING THE REAR BRAKE CALIPER..................................... 53

REAR SHOCK ABSORBER AND SWINGARM......................................... 54

HANDLING THE REAR SHOCK ABSORBER

AND GAS CYLINDER......................................................................... 56

DISPOSING OF THE REAR SHOCK ABSORBER

AND GAS CYLINDER......................................................................... 56

ELECTRICAL ................................................................................................... 57

ELECTRICAL COMPONENTS................................................................... 57

YFM350S WIRING DIAGRAM

– 1 –

GEN

INFO

GENERAL INFORMATION

MACHINE IDENTIFICATION

MODEL LABEL

The model label 1 is affixed to the frame. This

information will be needed to order spare

parts.

MACHINE IDENTIFICATION

– 2 –

GEN

INFO

SPECIAL TOOLS

EB102001

SPECIAL TOOLS

The following special tools are necessary for complete and accurate tune-up and assembly. Use

only the appropriate special tools; this will help prevent damage caused by the use of inappropriate

tools or improvised techniques. Special tools may differ by shape and part number from country to

country. In such a case, two types are provided.

When placing an order, refer to the list provided below to avoid any mistakes.

For US and CDN

P/N. YM-, YU-, YS-, YK-, ACC-

Except for US and CDN

P/N. 90890-

Tool No.

Tool name/How to use

Illustration

90890-01443

YU-33975

Steering nut wrench

This tool is needed to loosen and tighten

the rear shock absorber locknut.

90890-01498

YM-37134

Axle nut wrench (46 mm)

This tool is needed to loosen or tighten

the rear axle nut.

– 3 –

SPEC

SPECIFICATIONS

GENERAL SPECIFICATIONS

Model

YFM350S

Model code number

5YT1 (For USA and Oceania)

5YT2 (For CDN)

5YT3 (For Europe)

Dimensions

Overall length

1,770 mm (69.7 in)

Overall width

1,095 mm (43.1 in)

Overall height

1,080 mm (42.5 in)

Seat height

820 mm (32.3 in)

Wheelbase

1,210 mm (47.6 in)

Minimum ground clearance

115 mm (4.53 in)

Basic weight

With oil and full fuel tank

180.0 kg (397 lb)

Minimum turning radius

3,100 mm (122 in)

Engine

Engine type

Air-cooled 4-stroke, SOHC

Cylinder arrangement

Forward-inclined single cylinder

Displacement

349.0 cm³ (21.30 cu.in)

Bore × stroke

83.0 × 64.5 mm (3.27 × 2.54 in)

Compression ratio

9.20 : 1

Compression pressure

850 kPa (8.5 kg/cm², 120.9 psi) at 350 r/min

Starting system

Electric starter

Oil capacity

Engine oil

Periodic oil change

2.50 L (2.20 Imp qt, 2.64 US qt)

With oil filter replacement

2.60 L (2.29 Imp qt, 2.75 US qt)

Total amount

3.20 L (2.82 Imp qt, 3.38 US qt)

Fuel

Type

Regular unleaded gasoline only

(For CDN and Europe)

Unleaded gasoline only (For USA and Oceania)

Tank capacity

9.0 L (1.98 Imp gal, 2.38 US gal)

Reserve amount

2.7 L (0.59 Imp gal, 0.71 US gal)

Carburetor

Type/manufacturer

BSR36/MIKUNI

GENERAL SPECIFICATIONS

– 4 –

SPEC

GENERAL SPECIFICATIONS

Transmission

Primary reduction system

Spur gear

Primary reduction ratio

76/24 (3.167)

Secondary reduction system

Chain drive

Secondary reduction ratio

38/13 (2.923)

Transmission type

Constant mesh, 6-speed forward, 1-speed

reverse

Operation

Left foot operation

Gear ratio

1st

36/16 × 20/27 × 29/18 (2.685)

2nd

33/20 × 20/27 × 29/18 (1.969)

3rd

29/23 × 20/27 × 29/18 (1.504)

4th

27/26 × 20/27 × 29/18 (1.239)

5th

25/28 × 20/27 × 29/18 (1.066)

6th

23/29 × 20/27 × 29/18 (0.946)

Reverse

33/16 × 33/10 (6.806)

Chassis

Frame type

Steel tube frame

Caster angle

6°

Trail

26.0 mm (1.02 in)

Toe-in (unloaded)

20 ~ 30 mm (0.79 ~ 1.18 in)

Tires

Type

Tubeless

Size

front

AT21 × 7-10

rear

AT20 × 10-9

Manufacturer

front

DUNLOP

rear

DUNLOP

Type

front

KT851B

rear

KT877A

Brakes

Front brake

type

Dual disc brake

operation

Right hand operation

Rear brake

type

Single disc brake

operation

Right foot operation

Electrical

Ignition system

DC C.D.I.

Generator system

A.C. magneto

Battery voltage/capacity

12 V/8.6 Ah

Battery type

YTZ10S

Bulb wattage × quantity

Headlight

12 V 30 W/30 W × 2

Tail/brake light

12 V 5 W/21 W × 1

Neutral indicator light

12 V 1.7 W × 1

Reverse indicator light

12 V 1.7 W × 1

Model

YFM350S

– 5 –

SPEC

MAINTENANCE SPECIFICATIONS

MAINTENANCE SPECIFICATIONS

ENGINE

Model

YFM350S

Rocker arm/rocker arm shaft

Rocker arm inside diameter

11.980 ~ 11.998 mm (0.4717 ~ 0.4724 in)

Rocker arm shaft outside diameter

11.961 ~ 11.971 mm (0.4709 ~ 0.4713 in)

Rocker-arm-to-rocker-arm-shaft clearance

0.009 ~ 0.037 mm (0.0004 ~ 0.0015 in)

Carburetor

I.D. mark

5YT1 00

Main jet

(M.J)

#142.5

Main air jet

(M.A.J)

#35

Jet needle

(J.N)

5JFC39-2

Needle jet

(N.J)

P-0M

Pilot jet

(P.J)

#22.5

Pilot air jet

(P.A.J.1)

#65

(P.A.J.2)

#165

Pilot outlet

(P.O)

1

Bypass 1

(B.P.1)

0.8

Bypass 2

(B.P.2)

0.8

Bypass 3

(B.P.3)

0.8

Pilot screw turns out

(P.S)

2-1/4 (For CDN, Europe, and Oceania)

Valve seat

(V.S)

2.5

Starter jet

(G.S)

#70

Throttle valve size

(Th.V)

#105

Fuel level

(F.L)

4 ~ 5 mm (0.16 ~ 0.20 in)

Above the float chamber mating surface

Float height

13.0 mm (0.51 in)

Engine idling speed

1,450 ~ 1,550 r/min

Intake vacuum

33.3 kPa (250 mmHg, 9.83 inHg)

– 6 –

SPEC

MAINTENANCE SPECIFICATIONS

Tightening torques

Part to be tightened

Part name ^Thread

size

Q’ty

Tightening torque

Remarks

Nm

m · kg ft · lb

Carburetor joint

Bolt

M8

2

20

2.0

14

Carburetor clamp (cylinder head side)

Screw

M4

1

3

0.3

2.2

Carburetor clamp (air filter case side)

Screw

M4

1

3

0.3

2.2

Air filter case

Screw

M4

1

3

0.3

2.2

Muffler and exhaust pipe

Bolt

M8

1

16

1.6

11

Muffler

Bolt

M8

2

34

3.4

24

Clutch cable holder

Bolt

M8

1

16

1.6

11

Right crankcase cover

Bolt

M6

15

10

1.0

7.2

Left crankcase cover

Bolt

M6

9

11

1.1

8.0

Crankshaft end cover

Bolt

M6

4

7

0.7

5.1

Bearing retainer (balancer shaft)

Screw

M6

2

7

0.7

5.1

Bearing retainer (main axle)

Screw

M6

2

7

0.7

5.1

Bearing retainer (left crankcase)

Screw

M5

2

7

0.7

5.1

Drive sprocket

Nut

M20

1

90

9.0

65

Use a lock

washer.

Stopper lever

Bolt

M6

1

10

1.0

7.2

Reverse shift cam stopper bolt

Bolt

M14

1

18

1.8

13

Drive select lever assembly

Bolt

M8

2

20

2.0

14

Drive select lever shift rod and

reverse shift cam

Bolt

M6

1

16

1.6

11

Shift rod (shift pedal) locknut

Nut

M6

2

8

0.8

5.8

– 7 –

SPEC

MAINTENANCE SPECIFICATIONS

CHASSIS

Model

YFM350S

Steering system

Lock-to-lock angle

Left

42.5°

Right

42.5°

Front suspension

Shock absorber stroke

90.0 mm (3.54 in)

Shock absorber spring free length

232.5 mm (9.15 in)

Spring rate

(K1)

32.00 N/mm (3.26 kg/mm, 182.72 lb/in)

(K2)

45.00 N/mm (4.59 kg/mm, 256.95 lb/in)

Spring stroke

(K1)

0 ~ 45.0 mm (0 ~ 1.77 in)

(K2)

45.0 ~ 90.0 mm (1.77 ~ 3.54 in)

Optional spring

No

Rear suspension

Shock absorber stroke

88.0 mm (3.46 in)

Shock absorber spring free length

238.5 mm (9.39 in)

Spring rate

(K1)

57.00 N/mm (5.81 kg/mm, 325.46 lb/in)

Stroke

0 ~ 88.0 mm (0 ~ 3.46 in)

Enclosed gas pressure

(standard)

1,500 kPa (15.0 kg/cm², 213.3 psi)

(Min)

1,450 kPa (14.5 kg/cm², 206.2 psi)

(Max)

1,550 kPa (15.5 kg/cm², 220.4 psi)

Wheel

Front wheel type

Panel wheel

Rear wheel type

Panel wheel

Front rim size/material

10 × 5.5 AT/Aluminum

Rear rim size/material

9 × 8.5 AT/Aluminum

Rim runout limit

Vertical

<2.0 mm (0.08 in)>

Lateral

<2.0 mm (0.08 in)>

Front disc brake

Type

Dual disc brake

Disc outside diameter × thickness

161.0 × 3.5 mm (6.34 × 0.14 in)

<Limit>

<3.0 mm (0.12 in)>

Pad thickness

4.2 mm (0.17 in)

<Limit>

<1.0 mm (0.04 in)>

Rear disc brake

Type

Single disc brake

Disc outside diameter × thickness

200.0 × 3.6 mm (7.87 × 0.14 in)

<Limit>

<3.1 mm (0.12 in)>

Pad thickness

4.5 mm (0.18 in)

<Limit>

<1.0 mm (0.04 in)>