2003 Polaris Scrambler 50-90 Sportsman 90 Predator 90 Service Manual, Page 40Get this manual
ENGINE and ringsSee Honing to Oversize in this chapterInspect cylinder for out of round
Piston Inspection 1Inspect the piston for scoring or cracks in piston crown or pin areaExcessive carbon buildup below the ring land is an indication of piston, ring, or cylinder wearIf damage is excessive, replace pistonPiston-to-cylinder clearance should not exceed .0047 (0.12 mm)Measure the piston 58 (15 mm) from bottomThen measure inside diameter of cylinderThe difference between these measurements should not exceed .0047 (0.12 mm)
Piston Ring Installed Gap Service Limit: .030! (0.75 mm) Piston Pin Hole Inspection 1Using telescoping gauge or similar bore gauge, measure the inside diameter of the piston pin hole on both sides of the pistonReplace if diameter exceeds .395 (10.03 mm)