YFM660R(N)²⁰⁰¹

5LP2-AE1

SERVICEMANUAL

YFM660R(N) 2001

SERVICE MANUAL

 2000 by Yamaha Motor Co., Ltd.

First Edition, July 2000

All rights reserved. Any reproduction or

unauthorized use without the written

permission of Yamaha Motor Co., Ltd.

is expressly prohibited.

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 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.

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 dam-

age to the machine.

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

WARNING

CAUTION:

NOTE:

EB002000

HOW TO USE THIS MANUAL

MANUAL ORGANIZATION

This manual consists of chapters for the main categories of subjects. (See “Illustrated 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 9 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 Chassis

5 Engine

6 Cooling system

7 Carburetion

8 Electrical

9 Troubleshooting

Illustrated symbols 0 to G are used to identify

the specifications appearing in the text.

0 Can be serviced with engine mounted

A Filling fluid

B Lubricant

C Special tool

D Torque

E Wear limit, clearance

F Engine speed

G Ω, V, A

Illustrated symbols H to N in the exploded

diagrams indicate the types of lubricants and

lubrication points.

H Apply engine oil

I Apply gear oil

J Apply molybdenum disulfide oil

K Apply wheel bearing grease

L Apply lightweight lithium soap base grease

M Apply molybdenum disulfide grease

N Apply silicon 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

O

P

GEN

INFO

SPEC

CHK

ADJ

CHAS

ENG

COOL

CARB

–

+

ELEC

TRBL

SHTG

T R

.

.

E

G

M

B

LS

M

S

L

M

N

LT

New

TABLE OF CONTENTS

GENERAL INFORMATION

GEN

INFO 1

SPECIFICATIONS

SPEC 2

PERIODIC CHECKS AND

ADJUSTMENTS

CHK

ADJ 3

CHASSIS

CHAS 4

ENGINE

ENG 5

COOLING SYSTEM

COOL 6

CARBURETION

CARB 7

ELECTRICAL

ELEC 8

TROUBLESHOOTING

TRBL

SHTG 9

–

+

GEN

INFO 1

GEN

INFO

CHAPTER 1.

GENERAL INFORMATION

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

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

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

IMPORTANT INFORMATION ........................................................................1-2

PREPARATION FOR REMOVAL PROCEDURES ..................................1-2

REPLACEMENT PARTS ..........................................................................1-2

GASKETS, OIL SEALS AND O-RINGS ...................................................1-2

LOCK WASHERS/PLATES AND COTTER PINS ....................................1-3

BEARINGS AND OIL SEALS ...................................................................1-3

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

CHECKING OF CONNECTIONS ...................................................................1-4

SPECIAL TOOLS ...........................................................................................1-5

GEN

INFO

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 air filter

case cover. This information will be needed to

order spare parts.

1 - 2

GEN

INFO

EB101000

IMPORTANT INFORMATION

PREPARATION FOR REMOVAL

PROCEDURES

1.Remove all dirt, mud, dust and foreign mate-

rial 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 disas-

sembly. This will speed up assembly 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 function and

appearance, but inferior in quality.

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

1 - 3

GEN

INFO

EB101030

LOCK WASHERS/PLATES AND COTTER

PINS

1.Replace all lock washers/plates 1 and cotter

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 visible.

When installing oil seals, apply a light coat-

ing of lightweight lithium base grease to the

seal lips. Oil bearings liberally when install-

ing, if appropriate.

1 Oil seal

CAUTION:

Do not use compressed air to spin the

bearings dry. This will damage the bearing

surfaces.

1 Bearing

EB101050

CIRCLIPS

1.Check all circlips carefully before reassem-

bly. Always replace piston pin clips after one

use. Replace distorted circlips. When install-

ing a circlip 1, make sure that the sharp-

edged corner 2 is positioned opposite the

thrust 3 it receives. See sectional view.

4 Shaft

IMPORTANT INFORMATION

1 - 4

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 terminals.

G When checking the wire harness be sure to

perform steps 1 to 3.

G As a quick remedy, use a contact revitalizer

available at most part stores.

G Check the connector with a pocket tester as

shown.

1 - 5

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

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.

Pot

90890-01274

Bolt

90890-01275

Crankshaft installer pot

Crankshaft installer bolt

These tools are used to install the crank-

shaft.

YU-90050

Crankshaft installer set

These tools are used to install the crank-

shaft.

Adapter

90890-04059

YM-90069

Spacer

90890-04081

YM-91044

Adapter

Spacer (crankshaft installer)

These tools are used to install the crank-

shaft.

90890-01016

Spacer

This tool is used to install the crankshaft.