Yamaha YZ250F, WR250F Repair Manual 2001-2003

• Yamaha YZ250F Four-Stroke, 2001-2003
• Yamaha WR250F Four-Stroke, 2001 to 2003

This chapter provides removal and service procedures for the following lower end components:

1. Crankcase, bearings and seals.



2. Crankshaft and connecting rod.



3. Transmission.

To access and service these components, the engine must be removed from the frame, and then dismantled of all assemblies attached to the crankcase.

Read this chapter before attempting repairs to the engine lower end. Become familiar with the procedures, photos and illustrations to understand the skill and equipment required.

Refer to Chapter One for tool usage and techniques. Refer to Chapter Three for break-in procedures.

Throughout the text, mention of the left and right side of the engine refers to the engine as it sits in the motorcycle's frame, not as it sits on the workbench.

Table 1 and Table 2 are at the end of this chapter.

Prior to removing and disassembling the engine, clean the engine and frame with degreaser. The disassembly job will go easier and there will be less chance of dirt entering the assemblies.

Keep the work environment as clean as possible. Store parts and assemblies in well-marked plastic bags and containers. Keep reconditioned parts wrapped until they will be installed.


ENGINE

The following removal and installation procedures outline the steps necessary to remove the engine from the frame. It assumes the engine is being removed so the crankcase can be split to perform transmission or crankshaft service.

Since the frame keeps the engine stabilized, it may be easier to remove many of the top end components, and those located behind the crankcase covers, while the engine remains in the frame.

Tight nuts and bolts are easier to remove if the engine is held steady. Also, the actual engine problem may be discovered in another assembly, other than the crankcase.

• General Information
• Troubleshooting
• Lubrication, Maintenance and Tune-up
• Engine
• Clutch and External Gearshift Linkage
• Transmission and Internal Shift Mechanism
• Fuel and Emission Systems
• Exhaust System
• Electrical System
• Wheels, Tires and Drivetrain
• Front Suspension and Steering
• Rear Suspension
• Brakes
• Body and Frame
• Wiring Diagrams