YAMAHA YZ250F 2015 User Guide

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TABLE OF CONTENTS
GENERAL INFORMATION
SPECIFICATIONS
PERIODIC CHECKS AND ADJUST-
MENTS
CHASSIS
ENGINE
COOLING SYSTEM
FUEL SYSTEM
ELECTRICAL SYSTEM
TROUBLE SHOOTING
TUNING

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GENERAL INFORMATION
LOCATION OF IMPORTANT LABELS............................................................ 1-1
DESCRIPTION.................................................................................................. 1-4
IDENTIFICATION............................................................................................. 1-5
VEHICLE IDENTIFICATION NUMBER ...................................................... 1-5
ENGINE SERIAL NUMBER ....................................................................... 1-5
MODEL LABEL........................................................................................... 1-5
FEATURES....................................................................................................... 1-6
OUTLINE OF THE FI SYSTEM .................................................................. 1-6
FI SYSTEM................................................................................................. 1-7
INCLUDED PARTS.......................................................................................... 1-8
SIDESTAND ............................................................................................... 1-8
SPARK PLUG WRENCH ........................................................................... 1-8
NIPPLE WRENCH...................................................................................... 1-8
HANDLEBAR PROTECTOR ...................................................................... 1-8
FUEL HOSE JOINT COVER ...................................................................... 1-8
COUPLER FOR CONNECTING OPTIONAL PART................................... 1-8
IMPORTANT INFORMATION........................................................................ 1-10
PREPARATION FOR REMOVAL AND DISASSEMBLY.......................... 1-10
REPLACEMENT PARTS.......................................................................... 1-10
GASKETS, OIL SEALS AND O-RINGS ................................................... 1-11
LOCK WASHERS/PLATES AND COTTER PINS .................................... 1-11
BEARINGS AND OIL SEALS ................................................................... 1-11
CIRCLIPS ................................................................................................. 1-11
BASIC SERVICE INFORMATION.................................................................. 1-12
ELECTRICAL SYSTEM............................................................................ 1-12
SPECIAL TOOLS........................................................................................... 1-15
CONTROL FUNCTIONS................................................................................ 1-20
ENGINE STOP SWITCH .......................................................................... 1-20
CLUTCH LEVER...................................................................................... 1-20
SHIFT PEDAL .......................................................................................... 1-20
KICKSTARTER LEVER............................................................................ 1-20
THROTTLE GRIP ..................................................................................... 1-20
FRONT BRAKE LEVER ........................................................................... 1-20
REAR BRAKE PEDAL.............................................................................. 1-21
STARTER KNOB/IDLE ADJUSTING SCREW ......................................... 1-21
FUEL TANK CAP ..................................................................................... 1-21

STARTING AND BREAK-IN.......................................................................... 1-22
FUEL ........................................................................................................ 1-22
STARTING A COLD ENGINE .................................................................. 1-22
STARTING A WARM ENGINE ................................................................. 1-23
BREAK-IN PROCEDURES ...................................................................... 1-23
MAINTENANCE AFTER BREAK-IN.............................................................. 1-24
MAJOR MAINTENANCE .......................................................................... 1-24
TORQUE-CHECK POINTS............................................................................ 1-25
CLEANING AND STORAGE.......................................................................... 1-27
CLEANING ............................................................................................... 1-27
STORAGE ................................................................................................ 1-27

LOCATION OF IMPORTANT LABELS
1-1
EAS1SM5008
LOCATION OF IMPORTANT LABELS
Please read the following important labels carefully before operating this vehicle.
CAN
9,10,11 7,8
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12 1,2,3 4,5,6

LOCATION OF IMPORTANT LABELS
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EUR

LOCATION OF IMPORTANT LABELS
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AUS, NZL, ZAF

DESCRIPTION
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EAS1SM5009
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 pur-
chased.1. Clutch lever 10. Coolant drain bolt
2. Front brake lever 11. Rear brake pedal
3. Throttle grip 12. Air filter
4. Radiator cap 13. Drive chain
5. Fuel tank cap 14. Shift pedal
6. Engine stop switch 15. Oil level check window
7. Fuel tank 16. Starter knob/idle screw
8. Kickstarter lever 17. Front fork
9. Radiator
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IDENTIFICATION
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EAS1SM5010
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 iden-
tification of the model you own.
2. If your vehicle is stolen, the authorities will
need the number to search for and identify
your vehicle.
EAS1SM5011VEHICLE IDENTIFICATION NUMBER
The vehicle identification number “1” is
stamped into the right side of the frame.
EAS1SM5012ENGINE SERIAL NUMBER
The engine serial number “1” is stamped into
the elevated part of the right-side of the engine.
EAS1SM5013MODEL LABEL
The model label “1” is affixed to the rear frame.
This information will be needed to order spare
parts.
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FEATURES
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EAS20170
FEATURES
EAS1SM5014OUTLINE OF THE FI SYSTEM
The main function of a fuel supply system is to provide fuel to the combustion chamber at the opti-
mum air-fuel ratio in accordance with the engine operating conditions and the atmospheric tempera-
ture. In the conventional carburetor system, the air-fuel ratio of the mixture to be supplied to the
combustion chamber is determined by the amount of intake air and fuel that is measured on the basis
of the jets to be used in the carburetor.
Despite the same amount of intake air, the fuel amount requirement varies with the engine operating
conditions (acceleration, deceleration, and operation under a heavy load). The carburetor that mea-
sures fuel through the use of jets are provided with various auxiliary devices, so that the optimum air
fuel ratio can be obtained to accommodate frequent changes in the operating conditions of the en-
gine. This model has adopted an electronically controlled fuel injection (FI) system, in place of the
conventional carburetor system. This system can obtain the optimum air-fuel ratio required by the
engine at all times by using a microprocessor that regulates the fuel injection amount according to
the engine operating conditions detected by various sensors.
1. Fuel injector
2. Throttle position sensor
3. Intake air pressure sensor
4. Intake air temperature sensor
5. ECU
6. Fuel pump
7. Condenser
8. Crankshaft position sensor
9. Coolant temperature sensor
10.Ignition coil
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