ATV Service Manual 1988-1992 Vol. 2 - Honda, Kawasaki, Polaris, Suzuki, Yamaha

TROUBLESHOOTING: FAULTY RUNNING ENGINE

The diagnosis of trouble in a running engine depends on experience, knowledge and acute observation. A continuous miss on one cylinder of a two-cylinder engine usually can be isolated by observing the items listed in the previous paragraphs under FAILS TO START.

Faults, such as not enough power or speed, usually can be traced to improper tuning. Make sure that air filter is clean and in good condition, and the exhaust pipe and muffler are open (not clogged).

Ignition timing and carburetor(s) must be correctly adjusted. The carburetor jet sizes, clip position in valve needle and idle mixture needle settings listed in the individual service sections in this manual are "normal" settings.

Altitude above sea level, rider's weight, driving habits, etc., may require different sizes and settings than those listed.

On engines with two carburetors, make certain the throttles are synchronized to open exactly the same amount.

Ignition timing on two-cylinder engines must be the same for each cylinder.

In addition to normal engine tuning procedures, check the following:

• Sprocket sizes incorrect
• Drive chain too tight or too loose
• Tire pressure too low
• Brakes dragging
• Clutch slipping
• Damaged pistons, rings and/or cylinders
• Loose cylinder head nuts
• Leaking head gasket
• Leaking crankcase seals

LUBRICATION

Refer to the appropriate MAINTENANCE section for each model for recommended type and quantity of lubrication oils used in engine and gear box.


OIL PUMP ADJUSTMENT

Some models are equipped with a separate oil tank and pump for lubricating the engine. It is important that the oil pump is properly adjusted to provide the correct amount of oil.

If the pump does not deliver the correct amount of oil, the engine may be damaged. Refer to the appropriate engine section for adjustment procedure.

It is recommended that adjustment be checked periodically to make sure oil delivery is correct. Wear and/or control cable stretch will decrease the amount of oil delivered.


CLUTCH CONTROL

Clutch cable and/or control linkage is usually provided with adjustments to compensate for some stretch in cable and small amount of clutch plate wear.

Clutch linkage should not prevent clutch from completely engaging and when the control is actuated, clutch should not drag. Refer to appropriate section for adjustment procedure and requirements of each model.

• Operating Principles
• Carburetion
• Ignition System

• Troubleshooting
• Maintenance: Spark Plug, Carburetor, Ignition, 4-Stroke Valve System, Lubrication, Clutch Control