SERVICE MANUAL

YFM400FWA(M)

5GH3-AE1

2000

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YFM400FWA(M) 2000

SERVICE MANUAL

1999 by Yamaha Motor Co., Ltd.

First Edition, July 1999

All rights reserved. Any reproduction or

unauthorized use without the written

permission of Yamaha Motor Co., Ltd.

is expressly prohibited.

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EB001000

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 mainte-

nance 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 significant 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.

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 inspecting or

repairing the machine.

A CAUTION indicates special precautions that must be taken to avoid

damage to the machine.

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

WARNING

CAUTION:

NOTE:

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EB002000

HOW TO USE THIS MANUAL

MANUAL ORGANIZATION

This manual consists of chapters for the main categories of subjects. (See “Illustrated sym-

bols”)

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

accompanied 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.

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EB003000

ILLUSTRATED SYMBOLS

Illustrated symbols 1 to 0 are printed on

the top right of each page and indicate the

subject of each chapter.

1 General information

2 Specifications

3 Periodic inspections and adjustments

4 Engine

5 Cooling system

6 Carburetion

7 Drive train

8 Chassis

9 Electrical

0 Troubleshooting

Illustrated symbols A to H are used to

identify the specifications appearing in the

text.

A Can be serviced with engine mounted

B Filling fluid

C Lubricant

D Special tool

E Torque

F Wear limit, clearance

G Engine speed

H Ω, V, A

Illustrated symbols I to N in the exploded

diagrams indicate the types of lubricants

and lubrication points.

I Apply engine oil

J Apply gear oil

K Apply molybdenum disulfide oil

L Apply wheel bearing grease

M Apply lightweight lithium-soap base grease

N Apply molybdenum disulfide grease

Illustrated symbols O to P in the exploded

diagrams indicate where to apply a locking

agent O and when to install a new part P.

O Apply the locking agent (LOCTITE^)

P Replace

1

2

3

4

5

6

7

8

9

0

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

GEN

INFO

SPEC

INSP

ADJ

ENG

COOL

CARB

DRIV

CHAS

–

+

ELEC

TRBL

SHTG

T R

.

.

G

M

E

B

LS

M

LT

New

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TABLE OF CONTENTS

GENERAL INFORMATION

1

SPECIFICATIONS

SPEC 2

PERIODIC INSPECTION AND

ADJUSTMENTS

3

ENGINE

ENG 4

COOLING SYSTEM

COOL 5

CARBURETION

CARB 6

DRIVE TRAIN

DRIV 7

CHASSIS

CHAS 8

ELECTRICAL

ELEC 9

TROUBLESHOOTING

10

GEN

INFO

INSP

ADJ

–

+

TRBL

SHTG

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GEN

INFO 1

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GEN

INFO

CHAPTER 1.

GENERAL INFORMATION

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

VEHICLE IDENTIFICATION NUMBER ..................................................1-1

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

FEATURES ....................................................................................................1-2

LIQUID COOLING ENGINE ...................................................................1-2

PARK POSITION ...................................................................................1-2

IMPORTANT INFORMATION

.......................................................................1-3

PREPARATION FOR REMOVAL PROCEDURES .................................1-3

REPLACEMENT PARTS ........................................................................1-3

GASKETS, OIL SEALS AND O-RINGS ................................................1-3

LOCK WASHERS/PLATES AND COTTER PINS ..................................1-4

BEARINGS AND OIL SEALS ................................................................1-4

CIRCLIPS ...............................................................................................1-4

CHECKING OF CONNECTIONS

...................................................................1-5

SPECIAL TOOLS

...........................................................................................1-6

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GEN

INFO

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1 - 1

GEN

INFO

MACHINE IDENTIFICATION

GENERAL INFORMATION

MACHINE IDENTIFICATION

VEHICLE IDENTIFICATION NUMBER

The vehicle identification number 1 is

stamped into the left side of the frame.

MODEL LABEL

The model label 1 is affixed to the frame.

This information will be needed to order

spare parts.

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1 - 2

GEN

INFO

FEATURES

LIQUID COOLING ENGINE

Compact liquid cooled 45˚ inclined engine.

A liquid cooling system has been incorpo-

rated for stable power and engine endur-

ance.

1 Radiator

2 Thermo switch

3 Fan motor

PARK POSITION

When the drive select lever is shifted into

the park position, a stopper lever is

engaged into the stopper gear preventing

the drive select lever and transmission from

moving.

When the drive select lever is at the “L”,

“H”, “N”, or “R” positions, the stopper

lever end

1

is moved away from the stop-

per gear

2

by the return spring

3

.

When the drive select lever is in the “P”

position, the lever cam

4

at the side of the

shift cam

5

lifts the stopper lever end

6

and the stopper lever end locks the drive

axle

7

.

When the stopper lever end

1

is not syn-

chronized, a torsion spring

8

retains the

rotation force of the shift cam

5

until it is

synchronized.

FEATURES

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1 - 3

GEN

INFO

EB101000

IMPORTANT INFORMATION

PREPARATION FOR REMOVAL

PROCEDURES

1.Remove all dirt, mud, dust and foreign

material before removal and disassembly.

2.Use proper tools and cleaning equipment.

Refer to the “SPECIAL TOOLS” section.

3.When disassembling the machine, always

keep mated parts together. This includes

gears, cylinder, piston and other parts that

have been “mated” through normal wear.

Mated parts must always be reused or

replaced as an assembly.

4.During machine disassembly, clean all

parts and place them in trays in the order

of disassembly. This will speed up assem-

bly and allow for the correct installation of

all parts.

5.Keep all parts away from any source of

fire.

EB101010

REPLACEMENT PARTS

1.Use only genuine Yamaha parts for all

replacements. Use oil and grease recom-

mended by Yamaha for all lubrication

jobs. Other brands may be similar in func-

tion and appearance, but inferior in qual-

ity.

EB101020

GASKETS, OIL SEALS AND O-RINGS

1.Replace all gaskets, seals and O-rings

when overhauling the engine. All gasket

surfaces, oil seal lips and O-rings must be

cleaned.

2.Properly oil all mating parts and bearings

during reassembly. Apply grease to the oil

seal lips.

IMPORTANT INFORMATION

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GEN

INFO

1 - 4

EB101030

LOCK WASHERS/PLATES AND COTTER

PINS

1.Replace all lock washers/plates

1

and cot-

ter pins after removal. Bend lock tabs

along the bolt or nut flats after the bolt or

nut has been tightened to specification.

EB101040

BEARINGS AND OIL SEALS

1.Install bearings and oil seals so that the

manufacturer’s marks or numbers are vis-

ible. When installing oil seals, apply a

light coating of lightweight lithium base

grease to the seal lips. Oil bearings liber-

ally when installing, if appropriate.

1 Oil seal

CAUTION:

Do not use compressed air to spin the bear-

ings dry. This will damage the bearing sur-

faces.

1 Bearing

EB101050

CIRCLIPS

1.Check all circlips carefully before reas-

sembly. Always replace piston pin clips

after one use. Replace distorted circlips.

When installing a circlip

1

, make sure

that the sharp-edged corner

2

is posi-

tioned opposite the thrust

3

it receives.

See sectional view.

4 Shaft

IMPORTANT INFORMATION

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1 - 5

GEN

INFO

CHECKING OF CONNECTIONS

EB801000

CHECKING OF CONNECTIONS

Check the connectors for stains, rust, mois-

ture, etc.

1.Disconnect:

G Connector

2.Check:

G Connector

Moisture → Dry each terminal with an air

blower.

Stains/rust

→

Connect and disconnect the

terminals several times.

3.Check:

G Connector leads

Looseness → Bend up the pin 1 and con-

nect the terminals.

4.Connect:

G Connector terminals

NOTE:

The two terminals “click” together.

5.Check:

G Continuity (using a pocket tester)

NOTE:

G If there is no continuity, clean the termi-

nals.

G When checking the wire harness be sure

to perform steps 1 to 3.

G As a quick remedy, use a contact revital-

izer available at most part stores.

G Check the connector with a pocket tester

as shown.

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GEN

INFO

1 - 6

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

Bolt

90890-01083

Weight

90890-01084

Set

YU-01083-A

Slide hammer bolt (M6)/weight/set

These tools are used to remove the

rocker arm shaft.

90890-01135

YU-01135-A

Crankcase separating tool

This tool is used to separate the crank-

case.

90890-01225

YM-01225-A

Valve guide remover (7.0 mm)

This tool is needed to remove and

install the valve guide.

90890-04017

YM-04017

Valve guide installer (7.0 mm)

This tool is needed to install the valve

guide.

90890-01227

YM-01227

Valve guide reamer (7.0 mm)

This tool is needed to rebore the new

valve guide.

90890-01231

YM-01231

Gear lash measurement tool

This tool is used to measure the gear

lash.

90890-01235

YU-01235

Rotor holding tool

This tool is needed to hold the starter

puller when removing/installing the

starter puller bolt or camshaft sprocket

bolts.

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