Yamaha Moto-4, Big Bear Repair Manual 1987-2004

• Yamaha YFM350 2-WD, 1987-1999
• Yamaha YFM350FW 4-WD, 1987-1999
• Yamaha YFM400 2-WD, 2000-2004
• Yamaha YFM400 FW 4-WD, 2000-2004

Diagnosing mechanical and electrical problems is relatively simple if you use orderly procedures and keep a few basic principles in mind.

The first step in any troubleshooting procedure is to define the symptoms closely and then localize the problem. Subsequent steps involve testing and analyzing those areas that could cause the symptoms.

A haphazard approach may eventually solve the problem, but it can be very costly in wasted time and unnecessary parts replacement.

Proper lubrication, maintenance and periodic tune-up, as described in Chapter Three, will reduce the necessity for troubleshooting.

Even with the best of care, however, all vehicles are prone to problems that will require troubleshooting.

Never assume anything. Do no overlook the obvious. If the engine will not start, the engine stop switch or start switch may be shorted out or damaged.

When trying to start the engine, you may have flooded it.

If the engine suddenly quits, what sound did it make? Consider this and check the easiest, most accessible area first.

If the engine sounded as if it ran out of fuel, make sure there is fuel in the tank. If there is fuel in the tank, is it reaching the carburetor?

If not, the fuel tank vent hose may be plugged, preventing fuel from flowing from the fuel tank to carburetor.

• 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