2009 Polaris Outlaw 450/525 Service Manual, Page 210Get this manual
5-9 Checking the piston
Replace the piston if oil consumption is high or the piston skirt is excessively grooved If the piston is to be remounted: 1Check the piston bearing surface for damage 2Piston ring grooves: the piston rings must move freely in the grooveYou can use old piston rings to clean the piston ring grooves3Check the piston rings for damage and end gapMount the oil scraper ring with the "TOP" mark facing upMount the rectangular ring with the "O" mark facing up4Replace piston pins that are badly discolored or have visible running marksPlace the piston pin in the conrod and check for clearance
Checking the piston ring end gap