EAM20161

Read this manual carefully

Operating, servicing and

maintaining a passenger vehicle or off-road vehicle can

expose you to chemicals including engine exhaust,

carbon monoxide, phthalates, and lead, which are

known to the State of California to cause cancer and

birth defects or other reproductive harm. To minimize

exposure, avoid breathing exhaust, do not idle the

engine except as necessary, service your vehicle in a

well-ventilated area and wear gloves or wash your

hands frequently when servicing your vehicle. For more

information go to

www.P65Warnings.ca.gov/passenger-vehicle

EAM20161 Read this manual carefully before operating this vehicle. This manual should stay with this vehicle

if it is sold.

FCC CAUTION

Changes or modifications not expressly approved by the party responsible for compliance could void the user’s

authority to operate the equipment.

This transmitter must not be co-located or operated in conjunction with any other antenna or transmitter.

This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment and meets

the FCC radio frequency (RF) Exposure Guidelines. This equipment has very low levels of RF energy that is

deemed to comply without maximum permissive exposure evaluation (MPE).

EAM20080

YZ450FXK

OWNER’S SERVICE MANUAL

©2019 by Yamaha Motor Corporation, U.S.A.

First edition, May 2018

All rights reserved.

Any reprinting or unauthorized use

without the written permission of

Yamaha Motor Corporation, U.S.A.

is expressly prohibited.

Printed in Japan.

P/N. LIT-11626-32-25

EAM20081

INTRODUCTION

Congratulations on your purchase of a Yamaha YZ series. This model is the culmination of Yamaha’s

vast experience in the production of pacesetting racing machines. It represents the highest grade of

craftsmanship and reliability that have made Yamaha a leader.

This manual explains operation, inspection, basic maintenance and tuning of your machine. If you have

any questions about this manual or your machine, please contact your Yamaha dealer.

TIP

• Yamaha continually seeks advancements in product design and quality. Therefore, while this manual

contains the most current product information available at the time of printing, there may be minor dis­

crepancies between your machine and this manual. If you have any questions concerning this man­

ual, please consult your Yamaha dealer.

• This manual is intended for those who have basic knowledge and skill concerning the servicing of

Yamaha motorcycles (e.g., Yamaha dealers, service engineers, etc.). Those who have little knowl­

edge and skill concerning servicing are requested not to undertake inspection, adjustment, disassem­

bly, or reassembly only by reference to this manual. It may lead to servicing trouble and mechanical

damage.

WARNING

EWA20270

PLEASE READ THIS MANUAL CAREFULLY AND COMPLETELY BEFORE OPERATING THIS

MACHINE. DO NOT ATTEMPT TO OPERATE THIS MACHINE UNTIL YOU HAVE ATTAINED A

SATISFACTORY KNOWLEDGE OF ITS CONTROLS AND OPERATING FEATURES AND UNTIL

YOU HAVE BEEN TRAINED IN SAFE AND PROPER RIDING TECHNIQUES. REGULAR INSPEC­

TIONS AND CAREFUL MAINTENANCE, ALONG WITH GOOD RIDING SKILLS, WILL ENSURE

THAT YOU SAFETY ENJOY THE CAPABILITIES AND THE RELIABILITY OF THIS MACHINE.

EAM30001

IMPORTANT MANUAL INFORMATION

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

This is the safety alert symbol. It is used to alert you to potential per­

sonal injury hazards. Obey all safety messages that follow this symbol

to avoid possible injury or death.

A WARNING indicates a hazardous situation which, if not avoided, could

result in death or serious injury.

A NOTICE indicates special precautions that must be taken to avoid

damage to the vehicle or other property.

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

WARNING

NOTICE

TIP

EAM20092

SAFETY INFORMATION

THIS MACHINE IS DESIGNED STRICTLY FOR COMPETITION USE, ONLY ON A CLOSED

COURSE. It is illegal for this machine to be operated on any public street, road, or highway. Off-road

use on public lands may also be illegal. Please check local regulations before riding.

• THIS MACHINE IS TO BE OPERATED BY AN EXPERIENCED RIDER ONLY.

Do not attempt to operate this machine at maximum power until you are totally familiar with its char­

acteristics.

• THIS MACHINE IS DESIGNED TO BE RIDDEN BY THE OPERATOR ONLY.

Do not carry passengers on this machine.

• ALWAYS WEAR PROTECTIVE APPAREL.

When operating this machine, always wear an approved helmet with goggles or a face shield. Also

wear heavy boots, gloves, and protective clothing. Always wear proper fitting clothing that will not be

caught in any of the moving parts or controls of the machine.

• ALWAYS MAINTAIN YOUR MACHINE IN PROPER WORKING ORDER.

For safety and reliability, the machine must be properly maintained. Always perform the pre-operation

checks indicated in this manual.

Correcting a mechanical problem before you ride may prevent an accident.

• GASOLINE IS HIGHLY FLAMMABLE.

Always turn off the engine while refueling. Take care to not spill any gasoline on the engine or exhaust

system. Never refuel in the vicinity of an open flame, or while smoking.

• GASOLINE CAN CAUSE INJURY.

If you should swallow some gasoline, inhale excess gasoline vapors, or allow any gasoline to get into

your eyes, contact a doctor immediately. If any gasoline spills onto your skin or clothing, immediately

wash skin areas with soap and water, and change your clothes.

• ONLY OPERATE THE MACHINE IN AN AREA WITH ADEQUATE VENTILATION.

Never start the engine or let it run for any length of time in an enclosed area. Exhaust fumes are poi­

sonous. These fumes contain carbon monoxide, which by itself is odorless and colorless. Carbon

monoxide is a dangerous gas which can cause unconsciousness or can be lethal.

• PARK THE MACHINE CAREFULLY; TURN OFF THE ENGINE.

Always turn off the engine if you are going to leave the machine. Do not park the machine on a slope

or soft ground as it may fall over.

• THE ENGINE, EXHAUST PIPE AND MUFFLER WILL BE VERY HOT AFTER THE ENGINE HAS

BEEN RUN.

Be careful not to touch them or to allow any clothing item to contact them during inspection or repair.

• PROPERLY SECURE THE MACHINE BEFORE TRANSPORTING IT.

For safety, drain the gasoline from the fuel tank before transporting the vehicle.

EAM20162

YAMAHA MOTOR CORPORATION, U.S.A. YZ MOTORCYCLE LIMITED

WARRANTY

EAM20082

HOW TO USE THIS MANUAL

In this manual, descriptions of installation, removal, disassembly, assembly, check, and adjustment

procedures are laid out with the individual steps in sequential order.

• The manual is divided into chapters and each chapter is divided into sections. The current section title

“1” is shown at the top of each page.

• Sub-section titles “2” appear in smaller print than the section title.

• To help identify parts and clarify procedure steps, there are exploded diagrams “3” at the start of each

removal and disassembly section.

• Numbers “4” are given in the order of the jobs in the exploded diagram. A number indicates a removal

or a disassembly step.

• Symbols “5” indicate parts to be lubricated or replaced.

Refer to “SYMBOLS”.

• A job instruction chart “6” accompanies the exploded diagram, providing the order of jobs, the names

of parts, the notes in jobs, etc. This step explains removal and disassembly procedure only. For in­

stallation and assembly procedure, reverse the steps.

• Jobs “7” requiring more information (such as special tools and technical data) are described sequen­

tially.

1

7

3

4

6

2

5

EAM20083

SYMBOLS

The following symbols are used in this manual for easier understanding.

TIP

The following symbols are not relevant to every vehicle.

SYMBOL

DEFINITION

SYMBOL

DEFINITION

Serviceable with engine mounted

Gear oil

Filling fluid

Molybdenum disulfide oil

Lubricant

Brake fluid

Special tool

Wheel bearing grease

Tightening torque

Lithium-soap-based grease

Wear limit, clearance

Molybdenum disulfide grease

Engine speed

Silicone grease

Electrical data

Apply locking agent (LOCTITE®).

Engine oil

Replace the part with a new one.

G

M

BF

B

T R

.

.

LS

M

S

LT

E

New

GENERAL INFORMATION

1

SPECIFICATIONS

2

PERIODIC CHECKS AND

ADJUSTMENTS

3

CHASSIS

4

ENGINE

5

COOLING SYSTEM

6

FUEL SYSTEM

7

ELECTRICAL SYSTEM

8

TROUBLESHOOTING

9

TUNING

10

EAM10003 TABLE OF CONTENTS

1

2

3

4

5

6

7

8

9

10

GENERAL INFORMATION

LOCATION OF IMPORTANT LABELS.............................................................1-1

DESCRIPTION..................................................................................................1-2

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

VEHICLE IDENTIFICATION NUMBER ......................................................1-3

ENGINE SERIAL NUMBER........................................................................1-3

INCLUDED PARTS...........................................................................................1-4

NIPPLE WRENCH......................................................................................1-4

HANDLEBAR PROTECTOR ......................................................................1-4

FUEL HOSE JOINT COVER ......................................................................1-4

POWER TUNER.........................................................................................1-4

IMPORTANT INFORMATION ...........................................................................1-6

PREPARATION FOR REMOVAL AND DISASSEMBLY............................1-6

REPLACEMENT PARTS............................................................................1-6

GASKETS, OIL SEALS AND O-RINGS .....................................................1-7

LOCK WASHERS/PLATES AND COTTER PINS ......................................1-7

BEARINGS AND OIL SEALS .....................................................................1-7

CIRCLIPS ...................................................................................................1-7

BASIC SERVICE INFORMATION.....................................................................1-8

ELECTRICAL SYSTEM..............................................................................1-8

SPECIAL TOOLS............................................................................................1-12

CONTROL FUNCTIONS.................................................................................1-18

WARNING LIGHTS ..................................................................................1-18

ENGINE STOP SWITCH ..........................................................................1-18

START SWITCH.......................................................................................1-18

MODE SWITCH........................................................................................1-18

CLUTCH LEVER ......................................................................................1-19

SHIFT PEDAL...........................................................................................1-19

THROTTLE GRIP .....................................................................................1-19

FRONT BRAKE LEVER ...........................................................................1-19

REAR BRAKE PEDAL..............................................................................1-19

SIDESTAND .............................................................................................1-19

STARTER KNOB......................................................................................1-20

FUEL TANK CAP......................................................................................1-20

STARTING AND BREAK-IN...........................................................................1-21

FUEL.........................................................................................................1-21

AIR FILTER MAINTENANCE ...................................................................1-21

STARTING A COLD ENGINE ..................................................................1-21

STARTING A WARM ENGINE .................................................................1-22

BREAK-IN PROCEDURES ......................................................................1-22

ENGINE STARTING PRECAUTION ........................................................1-22

MAINTENANCE AFTER BREAK-IN ..............................................................1-23

MAJOR MAINTENANCE ..........................................................................1-23

TORQUE-CHECK POINTS.............................................................................1-24

MOTORCYCLE CARE AND STORAGE.........................................................1-26

CARE........................................................................................................1-26

STORAGE ................................................................................................1-27

LOCATION OF IMPORTANT LABELS

1-1

EAM20085

LOCATION OF IMPORTANT LABELS

Please read the following important labels carefully before operating this vehicle.

4,5

2

6

1

3

Premium unleaded

gasoline only.

3FB-2415E-02

4AA-22259-80

WARNING

This unit contains high pressure nitrogen gas.

Mishandling can cause explosion.

Read owner's manual for instructions.

Do not incinerate, puncture or open.

17D-2812P-00

For use only on a closed course

in sanctioned competition.

This motorcycle does not meet

EPA noise and emissions

standards and is not for general

off-road recreational riding.