2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 70Get this manual
ENGINE (300) 4Inspect cylinder for taper and out of round with telescoping gauge or dial bore gaugeMeasure in two different directions, front to back and side to side, on three different levels (12" down from top, in the middle, and 12" up from bottom)12" Down From Top of Cylinder Y
Honing To Deglaze
A finished cylinder should have cross-hatch pattern to ensure piston ring seating and to aid in the retention of the fueloil mixture during initial break inHone cylinder according to hone manufacturer's instructions, or these guidelines: Use motor speed of approximately 300-500 RPM, run the hone in and out of the cylinder rapidly until cutting tension decreasesRemember to keep the hone drive shaft centered (or cylinder centered on arbor) and to bring the stones approximately 12" (1.3 cm) above and below the bore at the end of each stroke Release the hone at regular intervals and inspect the bore to determine if it has been sufficiently deglazed, and to check for correct cross-hatchNOTE: Do not allow cylinder to heat up during honing After honing has been completed, THOROUGHLY clean the cylinder to remove all honing residueIMPORTANT: Clean the Cylinder After Honing Wash the cylinder in solvent, then in hot, soapy waterUse electrical contact cleaner if necessary to clean areas that cannot be scrubbedRinse thoroughly, dry with compressed air, and oil the bore immediately with Polaris Cycle Lubricant to prevent the formation of surface rustIf cylinder wear or damage is excessive, it will be necessary to replace the cylinderHone only enough to deglaze the outer layer of the cylinder bore