Yamaha YZ WR 400, 426, 450F Cyclepedia Printed Motorcycle Service Manual

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The Cyclepedia Yamaha YZ and WR 400, 426, and 450 printed motorcycle service manual features detailed black and white photographs and wiring diagrams, complete specifications with step-by-step procedures performed and written by a veteran Yamaha dealer trained motorcycle technician.

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The Yamaha YZ WR 400, 426, 450F motorcycle manual covers the following off-road and motocross motorcycles:

1998 Yamaha YZ400FK
1998 Yamaha WR400FK
1999 Yamaha YZ400FL
1999 Yamaha WR400FL
2000 Yamaha YZ426FM
2000 Yamaha WR400FM
2001 Yamaha YZ426FN
2001 Yamaha WR426FN
2002 Yamaha YZ426FP
2002 Yamaha WR426FP
2003 Yamaha YZ450FR
2003 Yamaha WR450FR
2004 Yamaha YZ450FS
2004 Yamaha WR450FS
2005 Yamaha YZ450FT
2005 Yamaha WR450FT

Table of Contents

Periodic Maintenance – Periodic Maintenance Chart, Clutch Cable Adjustment, Throttle Free Play, Engine Idle Speed, Drive Chain Adjustment, Hot Start Lever, Clutch Replacement, Engine Oil, Spark Plug, Compression Check, Air Filter Servicing, Transmission Oil, Tires, Brake Bleeding, Valve Clearance

Cooling System – Cooling System Specifications, Coolant, Radiators, Water Pump

Quick Reference
YZ450F Specifications
WR450F Specifications
YZ426F Specifications
WR426F Specifications
YZ400F Specifications
WR400F Specifications
VIN and Engine Number Location
General Torque Specifications

External Components
Side Covers
Fuel Tank
Brake Pedal
Brake Pedal
Front Number Plate
Sub Frame
Front Fender
Rear Fender
Exhaust System

Engine Specifications
Cylinder Head Cover
Cylinder Head
Camshaft Inspection
Camshaft Removal
Camshaft Installation
Kick Starter
Cylinder and Piston
Left Engine Components
Right Engine Components
Engine Removal
Engine Installation
Crankcase Splitting
Crankcase Assembly
Transmission Removal
Transmission Assembly
Crankcase Assembly
Engine Installation

Final Drive
Final Drive Specifications
Drive Chain
Engine Sprocket
Rear Wheel Sprocket

Front Brake
Brake Disc
Front Brake Specifications
Front Brake Caliper
Front Brake Replacement

Rear Brake
Rear Brake Caliper
Rear Brake Replacement
Rear Brake Specifications

Wheel Specifications
Front Wheel
Rear Wheel
Bearing Replacement

Bearing Replacement

Front Suspension – Fork Removal and Installation, Front Fork Assembly, Front Fork Disassembly, Fork Seal Replacement, Front Fork Specifications

Rear Suspension – Shock Removal and Installation, Specifications, Swing Arm

Electrical System
Electrical Specifications
Ignition System
Wiring Diagrams

The Yamaha YZ and WR series bikes covered by this manual share similarities and are known for their performance in motocross and off-road riding. While these models are generally reliable, riders have reported some common issues over the years. Here are potential concerns that owners might need to address:

Top-End Rebuilds: High-performance off-road bikes like the YZ and WR series may require periodic top-end rebuilds, including checking the condition of the piston, rings, and cylinder.

Valve Clearance Adjustment: Maintaining proper valve clearance is essential for engine performance. Riders should periodically check and adjust the valve clearances according to the manufacturer’s specifications.

Carburetor Issues: Some riders have reported carburetor-related issues, such as clogged jets or inconsistent idling. Regular carburetor cleaning and tuning may be necessary.

Starter and Electric System (WR Models): The WR models equipped with electric start may experience issues with the starter motor or electrical components. Regularly check the battery, starter motor, and associated wiring.

Cooling System Maintenance: Off-road riding can put a strain on the cooling system. Riders should ensure proper coolant levels, clean radiators, and inspect hoses for any signs of wear.

Suspension Components: The front forks and rear shock should be inspected regularly for leaks and wear. Suspension components are critical for off-road performance.

Chain and Sprockets: Off-road riding exposes the chain and sprockets to heavy stress. These bikes are very powerful and put additional stress on the drive train. Regularly inspect and replace these components as needed.

Brake System Maintenance: Off-road bikes require reliable braking. Regularly check brake pads, brake fluid levels, and ensure proper brake function.

Frame and Chassis Integrity: Off-road riding can subject the frame and chassis to significant stress. Inspect for cracks or damage and ensure the overall integrity of the bike’s structure.

Exhaust System Inspection: Check the exhaust system for any signs of damage, leaks, or loose components. Leaks can rob the bike of power.

Regular and proactive maintenance can address many of these concerns and help ensure a reliable and well-performing motorcycle.

Additional information

Weight 3.85 lbs
Dimensions 13 × 12 × 2 in