2010 Polaris Sportsman 850 Service Manual, Page 131Get this manual

2010 Polaris Sportsman 850 Service Manual, Page 131

ENGINE NOTE: When using an interference angle, the seat contact point on the valve will be very narrow, and is normal conditionLook
10Insert the valve into its respective guide and lap using lapping tool or section of fuel line connected to the valve stem11Rotate
the valve rapidly back and forth until the cut sounds smoothLift the valve slightly off of the seat, rotate 14 turn, and
repeat the lapping processDo this four to five times until the valve is fully seated, and repeat process for the other valve(s)12Thoroughly