2013 YAMAHA YZ450F fuel

FOREWORD
INTRODUCTION
Congratulations on your purchase of
a Yamaha YZ series. This model is
the culmination of Yamaha's vast ex-
perience in the production of paceset-
ting racing machines. It represents
the highest grade of craftsmanship
and reliability that have made Yama-
ha a leader.
This manual explains operation, in-
spection, basic maintenance and tun-
ing of your machine. If you have any
questions about this manual or your
machine, please contact your Yama-
ha dealer.
Yamaha continually seeks advance-
ments 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 discrepancies between
your machine and this manual. If you
have any questions concerning this
manual, please consult your Yamaha
dealer.
PLEASE READ THIS MANUAL
CAREFULLY AND COMPLETELY
BEFORE OPERATING THIS MA-
CHINE. DO NOT ATTEMPT TO OP-
ERATE THIS MACHINE UNTIL YOU
HAVE ATTAINED A SATISFACTO-
RY KNOWLEDGE OF ITS CON-
TROLS AND OPERATING
FEATURES AND UNTIL YOU HAVE
BEEN TRAINED IN SAFE AND
PROPER RIDING TECHNIQUES.
REGULAR INSPECTIONS AND
CAREFUL MAINTENANCE,
ALONG WITH GOOD RIDING
SKILLS, WILL ENSURE THAT YOU
SAFETY ENJOY THE CAPABILI-
TIES AND THE RELIABILITY OF
THIS MACHINE.
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 safe-
ty 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 in-
jury.
A NOTICE indicates special pre-
cautions that must be taken to
avoid damage to the vehicle or oth-
er property.
A TIP provides key information to
make procedures easier or clearer.
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 OPER-
ATED BY AN EXPERIENCED RID-
ER ONLY.
Do not attempt to operate this ma-
chine at maximum power until you
are totally familiar with its character-
istics.
• 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, al-
ways 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 MA-
CHINE IN PROPER WORKING
ORDER.
For safety and reliability, the ma-
chine must be properly maintained.
Always perform the pre-operation
checks indicated in this manual.
Correcting a mechanical problem
before you ride may prevent an ac-
cident.
• GASOLINE IS HIGHLY FLAMMA-
BLE.
Always turn off the engine while re-
fueling. 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 gaso-
line, inhale excess gasoline vapors,
or allow any gasoline to get into
your eyes, contact a doctor immedi-
ately. If any gasoline spills onto
your skin or clothing, immediately
wash skin areas with soap and wa-
ter, 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 poison-
ous. These fumes contain carbon
monoxide, which by itself is odor-
less and colorless. Carbon monox-
ide is a dangerous gas which can
cause unconsciousness or can be
lethal.
• PARK THE MACHINE CAREFUL-
LY; 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,
MUFFLER, AND OIL TANK WILL
BE VERY HOT AFTER THE EN-
GINE 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 MA-
CHINE BEFORE TRANSPORTING
IT.
For safety, drain the gasoline from
the fuel tank before transporting the
vehicle.

HOW TO USE THIS MANUAL
FINDING THE REQUIRED PAGE
1. This manual consists of eight
chapters; "General Information",
"Specifications", "Regular inspec-
tion and adjustments", "Engine",
"Chassis", "Fuel system", "Electri-
cal" and "Tuning".
2. The table of contents is at the be-
ginning of the manual. Look over
the general layout of the book be-
fore finding then required chapter
and item.
Bend the book at its edge, as
shown, to find the required fore
edge symbol mark and go to a
page for required item and de-
scription.
MANUAL FORMAT
All of the procedures in this manual
are organized in a sequential, step-
by-step format. The information has
been complied to provide the me-
chanic with an easy to read, handy
reference that contains comprehen-
sive explanations of all disassembly,
repair, assembly, and inspection op-
erations.
In this revised format, the condition of
a faulty component will precede an
arrow symbol and the course of ac-
tion required will follow the symbol,
e.g.,
• Bearings
Pitting/damage→Replace.

TABLE OF CONTENTS
GENERAL INFORMATION1
SPECIFICATIONS2
REGULAR INSPECTION AND
ADJUSTMENTS
3
ENGINE4
CHASSIS5
FUEL SYSTEM6
ELECTRICAL7
TUNING8

CONTENTS
CHAPTER 1
GENERAL INFOR-
MATION
LOCATION OF
IMPORTANT LABELS ..... 1-1
DESCRIPTION ................. 1-5
CONSUMER
INFORMATION................. 1-6
FEATURES....................... 1-7
INCLUDED PARTS .......... 1-9
IMPORTANT
INFORMATION................. 1-9
HANDLING THE
ELECTRONIC PARTS ... 1-10
CHECKING OF
CONNECTION ................ 1-10
SPECIAL TOOLS ........... 1-12
CONTROL
FUNCTIONS ................... 1-17
STARTING
AND BREAK-IN.............. 1-17
TORQUE-CHECK
POINTS........................... 1-19
CLEANING
AND STORAGE ............. 1-20
CHAPTER 2
SPECIFICATIONS
GENERAL
SPECIFICATIONS ............ 2-1
MAINTENANCE
SPECIFICATIONS ............ 2-3
TIGHTENING
TORQUES ...................... 2-11
LUBRICATION
DIAGRAMS .................... 2-17
CABLE ROUTING
DIAGRAM ....................... 2-18
CHAPTER 3
REGULAR INSPEC-
TION AND AD-
JUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION
AND MAINTENANCE ....... 3-5
ENGINE ............................ 3-6
CHASSIS ........................ 3-14
ELECTRICAL ................. 3-24
CHAPTER 4
ENGINE
SEAT
AND SIDE COVERS ......... 4-1
EXHAUST PIPE
AND SILENCER ............... 4-3
RADIATOR ....................... 4-5
CAMSHAFTS.................... 4-8
CYLINDER HEAD........... 4-13
VALVES AND
VALVE SPRINGS ........... 4-17
CYLINDER
AND PISTON .................. 4-21
CLUTCH ......................... 4-25
OIL FILTER ELEMENT
AND WATER PUMP ....... 4-29
BALANCER .................... 4-33
OIL PUMP ....................... 4-35
KICK SHAFT
AND SHIFT SHAFT ........ 4-38
AC MAGNETO................ 4-43
ENGINE REMOVAL ....... 4-45
CRANKCASE
AND CRANKSHAFT ...... 4-50
TRANSMISSION,
SHIFT CAM
AND SHIFT FORK .......... 4-56
CHAPTER 5
CHASSIS
FRONT WHEEL
AND REAR WHEEL .........5-1
FRONT BRAKE
AND REAR BRAKE..........5-6
FRONT FORK .................5-16
HANDLEBAR..................5-24
STEERING ......................5-28
SWINGARM ....................5-32
REAR
SHOCK ABSORBER ......5-37
CHAPTER 6
FUEL SYSTEM
FUEL TANK ......................6-1
THROTTLE BODY ............6-4
CHAPTER 7
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........7-1
IGNITION SYSTEM...........7-3
THROTTLE POSITION
SENSOR SYSTEM ...........7-6
FUEL INJECTION
SYSTEM............................7-9
FUEL PUMP SYSTEM ....7-35
ELECTRICAL
COMPONENTS...............7-36
CHAPTER 8
TUNING
CHASSIS ..........................8-1

1-5
DESCRIPTION
DESCRIPTION
• The machine you have purchased may differ slightly from those shown in the following.
• Designs and specifications are subject to change without notice.
1. Clutch lever
2. Front brake lever
3. Throttle grip
4. Radiator cap
5. Fuel tank cap
6. Engine stop switch
7. Kickstarter crank
8. Fuel tank
9. Radiator10. Coolant drain bolt
11. Rear brake pedal
12. Valve joint
13. Air cleaner
14. Drive chain
15. Shift pedal
16. Oil level check window
17. Starter knob/idle screw
18. Front fork

1-7
FEATURES
FEATURES
OUTLINE OF THE FI SYSTEM
The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum air-fuel ratio in ac-
cordance with the engine operating conditions and the atmospheric temperature. In the conventional carburetor system,
the air-fuel ratio of the mixture that is supplied to the combustionchamber is created by the volume of the intake air and the
fuel that is metered by the jet used in the respective carburetor.
Despite the same volume of intake air, the fuel volume requirement varies by the engine operating conditions,such as ac-
celeration, deceleration, or operating under a heavy load. Carburetors that meter thefuel through the use of jets have been
provided with various auxiliary devices, so that an optimum air-fuel ratio can be achieved to accommodate the constant
changes in the operating conditions of the engine.
This model has adopted an electronically controlled fuel injection (FI) system, in place of the conventional carburetor sys-
tem. This system can achieve an optimum air-fuel ratio required bythe engine at all times by using a microprocessor that
regulates the fuel injection volume according tothe engine operating conditions detected by various sensors.
1. Fuel injector
2. Throttle position sensor
3. Intake air pressure sensor
4. ECU
5. Fuel pump
6. Intake air temperature sensor7. Atmospheric pressure sensor
8. Crankshaft position sensor
9. Coolant temperature sensor
10. Ignition coil
11. Condenser

1-8
FEATURES
FI SYSTEM
The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains thefuel pressure that is
applied to the fuel injector at only 324 kPa (3.24 kgf/cm², 47.0 psi). Accordingly,when the energizing signal from the ECU
energizes the fuel injector, the fuel passage opens, causingthe fuel to be injected into the intake manifold only during the
time the passage remains open. Therefore, the longer the length of time the fuel injector is energized (injection duration),
the greater the volume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is energized (in-
jection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the throttle position
sensor, coolant temperature sensor, atmospheric pressure sensor, lean angle sensor, crankshaft position sensor, intake
air pressure sensor and intake air temperature sensor enable the ECU to determine the injection duration. The injection
timing is determined through the signals from the crankshaft position sensor. As a result, the volume of fuel that is required
by the engine can be supplied at all times in accordance with the driving conditions.
1. Fuel pump
2. Fuel injector
3. ECU
4. Throttle position sensor
5. Coolant temperature sensor
6. Crankshaft position sensor
7. Intake air pressure sensor
8. Throttle body
9. Intake air temperature sensor
10. Air filter case11. Atmospheric pressure sensor
A. Fuel system
B. Intake system
C. Control system
1
10
9B
87
6 5
A
23 C4
11

1-9
INCLUDED PARTS
INCLUDED PARTS
DETACHABLE SIDESTAND
This sidestand "1" is used to support
only the machine when standing or
transporting it.
• Never apply additional force to
the sidestand.
• Remove this sidestand before
starting out.
VALVE JOINT
This valve joint "1" prevents fuel from
flowing out and is installed to the fuel
tank breather hose.
In this installation, make sure the
arrow faces the fuel tank and also
downward.
SPARK PLUG WRENCH
This spark plug wrench "1" is used to
remove and install the spark plug.
NIPPLE WRENCH
This nipple wrench "1" is used to
tighten the spoke.HANDLEBAR PROTECTOR
Install the handlebar protector "1" so
that the mark "a" face forward.
FUEL TANK HOLDING CABLE
The fuel tank holding cable "1" is
used to support the fuel tank during
maintenance.
FUEL HOSE JOINT COVER
The fuel hose joint covers "1" are
used to prevent mud, dust, and other
foreign material from entering the fuel
pump when the fuel hose is discon-
nected.
COUPLER FOR CONNECTING
OPTIONAL PART
This coupler "1" is used for connec-
tion to an optional Power Tuner and
so on.
When no optional parts, etc. are
connected, connect the connec-
tion terminal to the original cou-
pler "2".
Before removing the coupler, thor-
oughly wipe off any mud or water
stuck to it.
IMPORTANT INFORMATION
PREPARATION FOR REMOVAL
AND DISASSEMBLY
1. Remove all dirt, mud, dust, and
foreign material before removal
and disassembly.
• When washing the machine with
high pressured water, cover the
parts follows.
Air duct
Silencer exhaust port
Drain hole on the cylinder head
(right side)
Water pump housing hole at the
bottom
2. Use proper tools and cleaning
equipment. Refer to "SPECIAL
TOOLS" section.
3. When disassembling the ma-
chine, keep mated parts together.
They include gears, cylinders,
pistons, and other mated parts
that have been "mated" through
normal wear. Mated parts must
be reused as an assembly or re-
placed.
Part name Part number
YZ Power Tuner 33D-859C0-10
The YZ Power Tuner is optional.