2009 Polaris Sportsman 850 XP EFI EPS Service Manual, Page 141Get this manual
ENGINE Piston Ring Installed Gap
1Place each piston ring (A) inside the cylinder (B) (from cylinder head side of crankcase)Use the piston to push the ring squarely into cylinder, as shown belowMeasure installed gap with feeler gauge (C) at both the top and bottom of the cylinder
Cylinder Inspection
123Remove all gasket material from gasket surfaceLay straight edge across cylinders (upper crankcase)Use thickness gauge to measure gap between straightedge and gasket surfaceMeasure at outer edges and center, repeating measurements with straightedge laid diagonallyIMPORTANT: difference between top and bottom end gap measurements is general indication of cylinder taper (wear)The cylinder should be measured for taper and out of roundHead gasket surface