2007-2011 Polaris IQ Snowmobiles Service Manual, Page 225Get this manual
Engine and Cooling Systems Piston Inspection
Check piston for scoring or cracks in piston crown or pin areaExcessive carbon buildup below the ring lands is an indication of piston, ring or cylinder wearMeasure piston outside diameter "at 90 angle to the direction of the piston pin and at the specified measuring pointPosition the ring 12" (1.3 cm) from the top of the cylinder using the piston to push it squarely into placeMeasure installed gap with feeler gauge at both the top and bottom of the cylinderNOTE: difference in end gap indicates cylinder taperThe cylinder should be measured for excessive taper and out-of-roundReplace rings if the installed end gap exceeds the service limitAlways check piston ring installed gap after reboring cylinder or when installing new rings