2010 Polaris Sportsman 850 Service Manual, Page 148Get this manual
ENGINE ENGINE ASSEMBLY
Crankcase PreparationUpper
1Refer to Oil Flow Diagram (page 5.4) and trace the oil path through the upper crankcasecylinderFlush all oil passages with solvent and then warm soapy waterRinse with clear, warm water and dry with compressed airBe sure passages are clean and dry before assembling the upper crankcase54Install second ring with undercut facing bottom of pistonRotate ring to place end gap generally toward (intake) side of piston as shown belowInstall top ring with "0" mark facing up (toward piston crown) and rotate to position the gap generally at the front as shown belowBe sure top and second rings rotate freely in their grooves and do not bind when compressed by handOil ring expander butt end Intake MAG Exhaust Oil ring rail Oil ring rail