2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 86Get this manual
ENGINE (300) Cylinder Installation
NOTE: Clean the gasket surfaces on the crankcase and cylinderRemove all traces of old gasket material or sealantThe surfaces must be oil-free! 1Apply small amount of crankcase sealant at the case parting lines (A)Do not allow sealant to dryAssemble the top end immediately6Install cylinder carefully with front to back rocking motion until rings are fully captive in the sleeve, then remove the compressor and support blockSeat the cylinder firmly onto the base gasketInstall the cam chain guide and dowel pins into the cylinderVerify the bottom end of the guide is seated properly in the crankcase