2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 148Get this manual
TROUBLESHOOTING, CONT
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
Low Compression
&&&&& 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