2010 Polaris Sportsman 850 Service Manual, Page 147Get this manual
ENGINE 6Measure in two directions (front to back and side to side) on three levels and record measurementsIf cylinder is tapered or out of round beyond .001", the crankcase must be replaced12" Down From Top
Piston-to-Cylinder Clearance
Measure piston outside diameter at point 33 mm down from piston crown, at right angle to piston pin boreSubtract measurement from maximum measurement obtained in Step of Cylinder Inspection