Yamaha YFM45FAR, YFM450FAR. Service Manual - part 1

YFM45FAR

YFM450FAR

5ND2-AE1

SERVICE MANUAL

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

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.

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 checks 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 lithium-soap-based 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

CHK

ADJ

ENG

COOL

CARB

DRIV

CHAS

–

+

ELEC

TRBL

SHTG

T

 

R

.

.

E

G

M

B

LS

M

LT

New

TABLE OF CONTENTS

GENERAL INFORMATION

GEN 

INFO

1 

SPECIFICATIONS

SPEC

2 

PERIODIC CHECKS AND 
ADJUSTMENTS

CHK

ADJ

3 

ENGINE

ENG

4 

COOLING SYSTEM

COOL

5 

CARBURETION

CARB

6 

DRIVE TRAIN

DRIV

7 

CHASSIS

CHAS

8 

ELECTRICAL

ELEC

9 

TROUBLESHOOTING

TRBL

SHTG

10 

–

+

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.

1 - 2

GEN

INFO

FEATURES

LIQUID COOLING ENGINE

Compact liquid cooled 45° inclined engine. A
liquid cooling system has been incorporated
for stable power and engine endurance.

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 stopper 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

synchronized, a torsion spring 

8

 retains the

rotation force of the shift cam 

5

 until it is

synchronized.

FEATURES

GEN

INFO

1 - 3

FEATURES

FRONT DIFFERENTIAL

1

Adapter

2

Drive clutch

3

Differential side gear (left)

4

Differential pinion gear

5

Ring gear

6

Differential side gear (right)

7

Drive pinion gear

8

Gear motor

È

To front wheel

É

From the middle gear

GEN

INFO

1 - 4

FEATURES

2WD

Power is transmitted as follows: middle gear 

→

 front drive shaft 

→

 drive pinion gear 

7

 

→

 ring gear

5

 

→

 differential pinion gear 

4

. In the 2WD mode, the left differential side gear 

3

 and the drive

clutch 

2

 are not engaged, therefore, the left side gear runs idle and does not transmit power to the

left front constant velocity joint.

GEN

INFO

1 - 5

FEATURES

4WD

When the 4WD mode is selected, the gear motor is operated, and the drive clutch 

2

 moves to the

right and engages with the left differential side gear 

3

. Accordingly, power is transmitted as follows:

ring gear 

5

 

→

 differential pinion gear 

4

 

→

 left differential side gear 

3

 

→

 drive clutch 

2

 

→

 adapter

1

 

→

 left front constant velocity joint.

Meanwhile, power from the differential pinion gear 

4

 is transmitted to the right front constant

velocity joint via the right differential side gear 

6

. 

The ring gear 

5

 and the drive clutch 

2

 are not engaged at this time. Therefore, the rotational

difference that occurs between the right and left wheels, while the handlebar is being turned, is
absorbed by the difference in the rotational speeds of the ring gear 

5

 and the left differential side

gear 

3

.

GEN

INFO

1 - 6

FEATURES

4WD (Diff-Lock)

When the 4WD (Diff-Lock) mode is selected, the gear motor moves the drive clutch 

2

 further to the

right, which causes the ring gear 

5

 and the drive clutch 

2

 to engage. As a result, power is

transmitted directly from the ring gear 

5

 to the drive clutch 

2

, then to the left front constant velocity

joint via the adapter 

1

.

Meanwhile, because the ring gear 

5

 and the drive clutch 

2

 are engaged, the ring gear 

5

, the drive

clutch 

2

, and the right differential side gear 

6

 become locked coaxially. Thus, power is transmitted

as follows: differential pinion gear 

4

 

→

 right differential pinion gear 

6

 

→

 right front constant

velocity joint.
When the ATV is in the 4WD (Diff-Lock) mode, the right and left wheels rotate constantly at the
same speed, which affects the maneuverability of the ATV (e.g., making it difficult to steer).
Therefore, the maximum traveling speed is limited to 35 km/h (22 mph). 

GEN

INFO

1 - 7

FEATURES

In addition, the 4WD (Diff-Lock) mode can be engaged only when the ATV is stopped. Even if an
attempt is made to select this mode when the ATV is traveling, it will only result in a standby
condition (i.e., when the differential lock select switch and the differential gear are not matched).
(1) When the ATV is traveling
Even if the 4WD (Diff-Lock) mode is selected, the gear motor will stand by, instead of operating.
Therefore, the ATV can be driven in the normal 4WD mode. When this occurs, the differential gear
lock indicator light “

” in the speedometer unit will flash to alert the driver that the control is on

standby. When the ATV is stopped, the control transfers to the condition described in (2).

(2) When the ATV is stopped
The gear motor operates to connect the drive clutch to the differential case, thus resulting in the
differential lock condition. When this occurs, the differential gear lock indicator light “

” in the

speedometer unit changes to a constant illumination.
* Until the drive clutch and the differential case mesh together (i.e., the splines are unmeshed) the
engine misfires to control the engine speed. During this time, the differential gear lock indicator light
in the speedometer unit continues to flash.

DIFF.

LOCK

DIFF.

LOCK

1 - 8

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 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
recommended 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 - 9

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
coating of lightweight lithium base grease to
the seal lips. Oil bearings liberally when
installing, 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

reassembly. 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 positioned

opposite the thrust 

3

 it receives. See

sectional view.

4

Shaft

IMPORTANT INFORMATION

1 - 10

GEN

INFO

CHECKING OF CONNECTIONS

EB801000

CHECKING OF CONNECTIONS

Check the connectors for stains, rust,
moisture, etc.

1.Disconnect:

●

Connector

2.Check:

●

Connector 
Moisture 

→

 Dry each terminal with an air

blower. 
Stains/rust 

→

 Connect and disconnect the

terminals several times.

3.Check:

●

Connector leads 
Looseness 

→

 Bend up the pin 

1

 and

connect the terminals.

4.Connect:

●

Connector terminals

NOTE:

The two terminals “click” together.

5.Check:

●

Continuity (using a pocket tester)

NOTE:

●

If there is no continuity, clean the terminals.

●

When checking the wire harness be sure to
perform steps 1 to 3.

●

As a quick remedy, use a contact revitalizer
available at most part stores.

●

Check the connector with a pocket tester as
shown.

GEN

INFO

1 - 11

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 
crankcase.

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.

90890-01235

YU-01235

Rotor holding tool
This tool is needed to hold the starter 
pulley when removing/installing the 
starter pulley bolt or camshaft 
sprocket bolts.

90890-04088

Bolt

90890-01275

Buffer boss installer set
Crankshaft installer bolt

These tools are used to install the 
crankshaft.

GEN

INFO

1 - 12

SPECIAL TOOLS

YU-90050

Crankshaft installer set

These tools are used to install the 
crankshaft.

Adapter

YM-33279

Spacer

90890-04060

YM-90070-A

Adapter (#11)
Spacer (crankshaft)

These tools are used to install the 
crankshaft.

90890-01304

YU-01304

Piston pin puller set

This tool is used to remove the piston 
pin.

90890-01311

YU-08035

Tappet adjusting tool (3 mm)

This tool is necessary for adjusting 
the valve clearance.

90890-01312

YM-01312-A

Fuel level gauge

This gauge is used to measure the 
fuel level in the float chamber.

90890-01325
YU-24460-01

Radiator cap tester

This tool is used to check the cooling 
system.

90890-01352

YU-33984

Adapter

This tool is used to check the cooling 
system.

90890-01348

Locknut wrench

This tool is needed when removing or 
installing the secondary sheave 
spring.

90890-04134

YM-04134

Sheave spring compressor

This tool is needed when removing or 
installing the secondary sheave 
spring.

Tool No.

Tool name/How to use

Illustration