1985-1995 Polaris ATV and Light Utility Hauler Service Manual, Page 339Get this manual
ENGINES Stroke Troubleshooting Excessive Smoke and Carbon Buildup
Excessive piston-to-cylinder clearance Wet sumping Worn rings, piston, or cylinder Worn valve guides or seals Restricted breather Air filter dirty or contaminated Decompressor stuck Cylinder head gasket leak No valve clearance or incorrectly adjusted Cylinder or piston worn Piston rings worn, leaking, broken, or sticking Bent valve or stuck valve Valve spring broken or weak Valve not seating properly (bent or carbon accumulated on sealing surface) Rocker arm sticking Low coolant levelair in system Faulty pressure cap or system leaks Lean mixture (restricted jets, vents, fuel pump or fuel valve) Fuel pump output weak Restricted radiator (internally or cooling fins) Water pump failure Cooling system restriction Cooling fan inoperative Ignition timing misadjusted Low oil level Spark plug incorrect heat range Faulty hot light circuit Thermostat stuck closed ETC or speed limiter system malfunction Fouled spark plug or incorrect plug or plug gap Carburetion faultylean condition Exhaust system air leaks Ignition system faulty: Spark plug cap crackedbroken Ignition coil faulty Ignition or kill switch circuit faulty Ignition timing incorrect Sheared flywheel key Poor connections in ignition system System wiring wet Valve sticking Air leaks in intake Lean condition