Yamaha YZ 2021 Series

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Read this manual carefully before operating this vehicle.

2021

OWNER’S SERVICE MANUAL

YZ250

YZ250X

YZ250

YZ250M

YZ250XM

BF1-2819U-50-E0

Main Page

Important Manual Information4
How to Use this Manual5
General Information7
Table of Contents9
Safety Information11
For Safety, be Sure to Obey the Following11
Location of Important Labels14
Description17
Identification18
Vehicle Identification Number18
Engine Serial Number18
Included Parts19
SIDESTAND (for YZ250)19
Nipple Wrench19
Valve Joint19
Set Pin19
Important Information20
Preparation for Removal and Disassembly20
Replacement Parts20
Gaskets, Oil Seals and O-Rings20
Lock Washers/Plates and Cotter Pins21
Bearings and Oil Seals21
Circlips21
Basic Service Information22
Electrical System22
Special Tools24
Instrument and Control Functions28
Engine Stop Switch28
Shift Pedal28
Kickstarter Lever28
Front Brake Lever28
Rear Brake Pedal28
FUEL COCK (for YZ250)28
FUEL COCK (for YZ250X)29
Starter Knob (Choke)29
SIDESTAND (for YZ250X)29
Starting and Break-In30
Fuel and Engine Mixing Oil30
Starting a Cold Engine30
Starting a Warm Engine30
Break-In Procedures30
Maintenance after Break-In32
Major Maintenance32
Air Filter Maintenance32
Torque-Check Points33
Motorcycle Care and Storage35
Care35
Storage36
Specifications40
General Specifications40
Engine Specifications41
Chassis Specifications44
Electrical Specifications47
Tightening Torques48
General Tightening Torque Specifications48
Engine Tightening Torques49
Chassis Tightening Torques51
Cable Routing Diagram54
Maintenance Intervals67
Pre-Operation Inspection and Maintenance70
General Inspection and Maintenance70
Engine71
Adjusting the Pilot Air Screw71
Checking the Engine Idling Speed71
Checking the Throttle Grip71
Checking the Spark Plug72
Checking the Transmission Oil Level72
Changing the Transmission Oil73
Adjusting the Clutch Lever Free Play73
Adjusting the Clutch Lever Position74
Cleaning the Air Filter Element74
Checking the Carburetor Joint75
Checking the Carburetor Hoses76
Checking the Exhaust System76
Checking the Coolant Level77
Checking the Cooling System77
Changing the Coolant77
Chassis79
Adjusting the Front Disc Brake79
Adjusting the Rear Disc Brake79
Checking the Brake Fluid Level80
Checking the Front Brake Pads80
Checking the Rear Brake Pads81
Checking the Front Brake Hose81
Checking the Rear Brake Hose81
Checking the Brake Operation81
Bleeding the Hydraulic Brake System81
Drive Chain Slack82
Lubricating the Drive Chain83
Checking and Adjusting the Steering Head83
Lubricating the Steering Head84
Checking the Front Fork Legs84
Adjusting the Front Fork Legs85
Checking the Rear Shock Absorber Assembly86
Adjusting the Rear Shock Absorber Assembly87
Checking the Swingarm Operation89
Lubricating the Swingarm Pivot89
Checking the Connecting Arm and Relay Arm89
Checking the Tires89
Checking and Tightening the Spokes89
Checking the Wheels90
Checking the Wheel Bearings90
Checking the Chassis Fasteners90
Checking and Lubricating the Cables90
Lubricating the Brake Lever90
Lubricating the Clutch Lever91
Lubricating the Pedal91
CHECKING the SIDESTAND (for YZ250X)91
LUBRICATING the SIDESTAND (for YZ250X)91
Electrical System92
Checking the Ignition Timing92
General Chassis95
Removing the Number Plate96
Removing the Side Cover96
Front Wheel97
Removing the Front Wheel98
Disassembling the Front Wheel98
Checking the Front Wheel98
Assembling the Front Wheel99
Installing the Front Wheel99
Rear Wheel101
Removing the Rear Wheel102
Disassembling the Rear Wheel102
Checking the Rear Wheel102
Checking and Replacing the Rear Wheel Sprocket102
Assembling the Rear Wheel103
Installing the Rear Wheel103
Front Brake105
Introduction109
Checking the Front Brake Disc109
Replacing the Front Brake Pads109
Removing the Front Brake Caliper111
Disassembling the Front Brake Caliper111
Checking the Front Brake Caliper111
Assembling the Front Brake Caliper112
Installing the Front Brake Caliper112
Removing the Front Brake Master Cylinder113
Checking the Front Brake Master Cylinder113
Assembling the Front Brake Master Cylinder113
Installing the Front Brake Master Cylinder114
Brake System115
Rear Brake116
Introduction120
Checking the Rear Brake Disc120
Replacing the Rear Brake Pads120
Removing the Rear Brake Caliper122
Disassembling the Rear Brake Caliper122
Checking the Rear Brake Caliper122
Assembling the Rear Brake Caliper122
Installing the Rear Brake Caliper123
Removing the Rear Brake Master Cylinder123
Checking the Rear Brake Master Cylinder124
Assembling the Rear Brake Master Cylinder124
Installing the Rear Brake Master Cylinder125
Handlebar127
Removing the Handlebar127
Checking the Handlebar127
Installing the Handlebar127
Front Fork132
Removing the Front Fork Legs134
Disassembling the Front Fork Legs134
Checking the Front Fork Legs135
Assembling the Front Fork Legs136
Installing the Front Fork Legs142
Steering Head144
Removing the Lower Bracket145
Checking the Steering Head145
Installing the Steering Head145
Rear Shock Absorber Assembly148
Handling the Rear Shock Absorber150
Disposing of a Rear Shock Absorber150
Removing the Rear Shock Absorber Assembly150
Checking the Rear Shock Absorber Assembly150
Checking the Connecting Arm and Relay Arm150
Installing the Relay Arm151
Installing the Rear Shock Absorber Assembly151
Swingarm153
Removing the Swingarm154
Checking the Swingarm154
Installing the Swingarm154
Chain Drive156
REMOVING the DRIVE CHAIN (for YZ250)157
REMOVING the DRIVE CHAIN (for YZ250X)157
CHECKING the DRIVE CHAIN (for YZ250)157
CHECKING the DRIVE CHAIN (for YZ250X)158
Checking the Drive Sprocket159
Checking the Rear Wheel Sprocket159
INSTALLING the DRIVE CHAIN (for YZ250)159
INSTALLING the DRIVE CHAIN (for YZ250X)160
Engine Removal165
Removing the Engine167
Installing the Engine167
Cylinder Head, Cylinder and Piston168
Removing the Cylinder Head170
Removing the Push Rod170
Removing the Piston170
Checking the Cylinder Head171
Checking the Cylinder and Piston171
Combination of Piston and Cylinder172
Checking the Piston Ring173
Checking the Piston Pin173
Checking the Small End Bearing174
Checking the Power Valve174
Checking the Power Valve Hole on Cylinder174
Assembling the Power Valve174
Installing the Piston and Cylinder176
Installing the Cylinder Head178
CDI Magneto179
Removing the Rotor180
Checking the CDI Magneto180
Checking the Woodruff Key180
Installing the CDI Magneto180
Kickstarter183
Removing the Primary Drive Gear183
Removing the Kick Shaft Assembly183
Checking the Kick Shaft and Ratchet Wheel183
Checking the Kick Gear, Kick Idle Gear and Ratchet Wheel183
Installing the Kick Shaft Assembly183
Installing the Kick Idle Gear184
Installing the Primary Drive Gear185
Installing the Kickstarter Lever185
Ypvs Governor186
Removing the Governor187
Checking the Governor Groove187
Checking the Bearing187
Installing the Governor187
Clutch191
Removing the Clutch191
Checking the Friction Plates191
Checking the Clutch Plates191
Checking the Clutch Springs191
Checking the Clutch Housing191
Checking the Clutch Boss192
Checking the Pressure Plate192
Checking the Push Lever Shaft192
Checking the Push Rods192
Checking the Primary Drive Gear192
Checking the Primary Driven Gear192
Installing the Clutch192
Shift Shaft195
Removing the Segment196
Checking the Shift Shaft196
Checking the Stopper Lever196
Installing the Shift Shaft196
Crankcase200
Disassembling the Crankcase200
Checking the Crankcase200
Assembling the Crankcase200
Crankshaft202
Removing the Crankshaft203
Checking the Crankshaft203
Installing the Crankshaft203
Transmission205
Removing the Transmission205
Checking the Shift Forks205
Checking the Shift Drum Assembly205
Checking the Transmission205
Installing the Transmission206
Cooling System210
Cooling System Diagrams210
Radiator212
Checking the Radiator212
Installing the Radiator212
Water Pump214
Disassembling the Water Pump215
Checking the Water Pump215
Assembling the Water Pump215
Fuel Tank218
Air Filter219
Carburetor223
Handling Note223
Checking the Carburetor223
Checking the Reed Valve224
Installing the Reed Valve224
Assembling the Carburetor225
Installing the Carburetor227
Measuring and Adjusting the Fuel Level228
Wiring Diagram230
Color Code230
Ignition System231
Troubleshooting231
Solenoid Valve System232
Troubleshooting232
Troubleshooting233
Adjusting the Throttle Po- Sition Sensor233
Throttle Position Sensor System233
Electrical Components234
Checking the Switches235
Checking the Ignition Spark Gap237
Checking the Spark Plug Cap237
Checking the Ignition Coil237
Checking the Pickup Coil238
Checking the Source Coil238
Checking the Solenoid Valve Operation239
Checking the Solenoid Valve Coil239
Handling Note240
Checking the Throttle Position Sensor Coil240
Changing and Adjusting the Throttle Position Sensor240
Idling Speed241
Checking the Throttle Position Sensor Input Voltage242
Troubleshooting244
General Information244
Engine258
Carburetor Setting258
Atmospheric Conditions and Carburetor Settings258
Test Run258
Effects of the Setting Parts on the Throttle Valve Opening259
Main Jet Adjustment259
Adjusting the Power Jet259
Pilot Air Screw Adjustment259
Pilot Jet Adjustment260
Jet Needle Adjustment260
Jet Needle Groove Position Adjustment261
Relationship with Throttle Opening261
Carburetor Setting Parts262
Road Condition and Examples of Carburetor Setting263
Examples of Carburetor Setting Depending on Symptom263
Change of the Heat Range of Spark Plugs265
Chassis266
Selection of the Secondary Reduction Ratio (Sprocket)266
Drive and Rear Wheel Sprockets Setting Parts266
Tire Pressure266
Front Fork Setting267
Change in Amount and Characteristics of Fork Oil267
Setting of Spring after Replacement267
Front Fork Setting Parts268
Rear Suspension Setting268
Choosing Set Length268
Setting of Spring after Replacement269
Rear Shock Absorber Setting Parts269
Suspension Setting (Front Fork)271
Suspension Setting (Rear Shock Absorber)272

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Yamaha YZ 2021 Series Specifications

General

Brand	Yamaha
Model	YZ 2021 Series
Category	Motorcycle
Language	English

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