2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 91Get this manual
TROUBLESHOOTING
Piston FailureScoring
G Lack of lubrication Dirt entering engine through cracks in air filter or ducts Engine oil dirty or contaminated
Excessive Smoke and Carbon Buildup
G Excessive piston-to-cylinder clearance Worn rings, piston, or cylinder Worn valves, guides or seals Restricted breather Air filter dirty or contaminated
Low Compression