Yamaha YZ450FX 2019 Application guide

B3J-28199-10■
LIT-11626-32-25
Read this manual carefully before operating this vehicle.
YZ450FXK
OWNER’S SERVICE MANUAL
YZ450FX
2019
PRINTED IN JAPAN
2018.05-0.3×2 !
(E)
PRINTED ON RECYCLED PAPER
2019
YZ450FXK
B3J-28199-10_2_cover_12mm.indd 1-3 2018/09/14 14:16:15

For your best ownership experience, think Genuine Yamaha!
Genuine Yamaha Parts – Genuine Yamaha replacement parts are the exact same parts as the ones
originally equipped on your vehicle, providing you with the performance and durability you have come to
expect. Why settle for aftermarket parts that may not provide full confidence and satisfaction?
Genuine Yamaha Accessories – Yamaha only offers accessories that meet our high standards for quality
and performance. Buy with confidence, knowing your Genuine Yamaha Accessories will fit right and
perform right – right out of the box.
Yamalube – Take care of your Yamaha with legendary Yamalube oils, lubricants, and care products.
They're formulated and approved by the toughest judges we know: the Yamaha engineering teams that
know your Yamaha from the inside out.
Genuine Yamaha Service Manuals – Get the same factory manual for your vehicle that the technicians
at your authorized Yamaha dealer use. Service manuals are available through your Yamaha dealer or you
can order them directly through yamahapubs.com.
Genuine Yamaha products are available only from your Yamaha dealer.
Find out more at yamaha-motor.com
postscript3-本文レイアウト準拠-.fm Page 1 Monday, May 23, 2011 1:39 PM
EAM20161Read 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
B3J-28199-10_1_cover_12mm.indd 4-6 2018/07/09 11:12:24

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.
4,52
6
13
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.

DESCRIPTION
1-2
EAM20086
DESCRIPTION
TIP
Designs and specifications of the vehicle are subject to change without notice. Therefore, please note
that the descriptions in this manual may be different from those for the vehicle you have purchased.
1
12
1314
15
1617181920
4
57 68910
11
2, 3
1. Clutch lever
2. Engine trouble warning light “ ”
3. Fuel level warning light “ ”
4. Front brake lever
5. Throttle grip
6. Start switch
7. Radiator cap
8. Fuel tank cap
9. Mode switch
10.Engine stop switch
11.Fuel tank
12.Radiator
13.Coolant drain bolt
14.Rear brake pedal
15.Air filter
16.Drive chain
17.Shift pedal
18.Oil level check window
19.Starter knob
20.Front fork

IDENTIFICATION
1-3
EAM20087
IDENTIFICATION
There are two significant reasons for knowing
the serial number of your vehicle:
1. When ordering parts, you can give the num-
ber to your Yamaha dealer for positive identi-
fication of the model you own.
2. If your vehicle is stolen, the authorities will
need the number to search for and identify
your vehicle.
EAM30002
VEHICLE IDENTIFICATION NUMBER
The vehicle identification number “1” is stamped
into the right side of the frame.
EAM30003
ENGINE SERIAL NUMBER
The engine serial number “1” is stamped into the
elevated part of the right-side of the engine.
1
1
1
1

INCLUDED PARTS
1-4
EAM20088
INCLUDED PARTS
EAM30005
NIPPLE WRENCH
The nipple wrench “1” is used to tighten the
spoke.
EAM30006
HANDLEBAR PROTECTOR
Install the handlebar protector “1” with the mark
“a” facing forward.
EAM30007
FUEL HOSE JOINT COVER
The fuel hose joint covers “1” are used to pre-
vent mud, dust, and other foreign materials from
entering the inside when the fuel hose is discon-
nected.
EAM30443
POWER TUNER
By downloading the Power Tuner app to your
smartphone and wirelessly connecting to the
CCU wireless network, you can adjust various
vehicle settings.
WARNING
EWA20460
• Do not operate the engine in a closed area.
The exhaust gas is poisonous.
• Never let flames near the servicing area.
NOTICE
ECA26050
• This application is designed for adjusting
the settings on a standard vehicle. In case
the engine specifications (muffler, com-
pression ratio, etc.) have been changed,
the performance may not match to the actu-
al settings.
• Do not run the engine with the smartphone
carried with you. Otherwise, the smart-
phone could be damaged.
TIP
•Download the Power Tuner app from the
Google© or Apple© store.
•For details about handling the smartphone,
read the owner’s manual of the smartphone.
Before connecting to the CCU wireless net-
work (in case of initial use of the Power Tun-
er app)
1. Remove the bolts and side cover (left).
2. Remove the CCU and record the CCU serial
number.
A
a
1
A
1
1. Bolt
2. Side cover (left)
1
1
1
2

INCLUDED PARTS
1-5
3. Install the removed CCU and side cover (left).
Connecting to the CCU wireless network
NOTICE
ECA26060
The CCU (Communication Control Unit) uses
weak radio waves. The CCU may not work in
the following situations.
• The CCU is placed in a location exposed to
strong radio waves or other electromagnet-
ic noise
• There are facilities nearby that are emitting
strong radio waves (TV or radio towers,
power plants, broadcasting stations, air-
ports, etc.)
• You are carrying or using communication
equipment such as radios or mobile
phones in close proximity of the CCU
• The CCU is in contact with or covered by a
metallic object
• Other vehicles equipped with a CCU are
nearby
In such situations, move the CCU to another
location and perform the operation again.
1. Turn on the smartphone.
2. For two minutes after the start switch is
pressed or while the engine is running (the
CCU is activated), input the CCU serial num-
ber into your smartphone and establish a
wireless connection.
3. Activate the Power Tuner app.
TIP
If the CCU wireless network cannot be detected,
operate the start switch again.
1. CCU coupler
2. Holder
3. CCU (Communication Control Unit)
3. CCU (Communication Control Unit)
a. CCU serial number
123
P/N: --
S/N:
MAC:
COMMUN.CONT.UNIT ASSY.
3
a

IMPORTANT INFORMATION
1-6
EAM20089
IMPORTANT INFORMATION
EAM30009
PREPARATION FOR REMOVAL AND
DISASSEMBLY
1. Before the jobs, completely remove mud,
dust, and the like in order to prevent the entry
of them into the inside during the jobs.
•Before cleaning with high-pressure water of
washers, cover the following parts.
Air duct
Silencer exhaust port
Drain hole on the cylinder head (right side)
Hole under the water pump housing
2. Use proper special tools and equipment. Re-
fer to “SPECIAL TOOLS” on page 1-12.
3. During disassembly, check and measure the
required parts, and make a record of them so
that you may refer to the record when install-
ing them. Moreover, arrange gears, cylin-
ders, pistons, and other parts for each section
so as not to confuse or lose them.
4. During disassembly, clean each of the parts,
and store them in trays for each section.
5. Flammable. Keep servicing areas away from
any source of fire.
6. During servicing, take special care not to re-
ceive an injury or a burn on the engine, the
exhaust pipe, the silencer, or the like.
7. If coolant is left adhered to the chassis, paint
and plating will be damaged. Therefore, rinse
it out with water in good time.
WARNING
EWA18970
Coolant is potentially harmful and should be
handled with special care.
• If it enters your eyes, wash it away with wa-
ter enough and then get medical attention
• If it splashes on your skin or clothes, quick-
ly wash it away with water and then with
soapy water.
• If it is swallowed, immediately induce vom-
iting and get medical attention.
EAM30010
REPLACEMENT PARTS
Make sure that the parts and grease or oil to be
used for repair of the vehicle, including periodic
replacement parts, are new YAMAHA genuine
parts and recommended parts.
Do not use any used parts, because these may
not be genuine though they have similar appear-
ances or because the quality may be changed
by aging.