2005-2007 Polaris Ranger 500 service manual, Page 84Get this manual
ENGINE Valve Seat Reconditioning
Valve Seat Inspection Inspect valve seat in cylinder head for pitting, burnt spots, roughness, and uneven surfaceIf any of the above conditions exist, the valve seat must be reconditionedIf the valve seat is cracked the cylinder head must be replacedCylinder Head Reconditioning NOTE: Servicing the valve guides and valve seats requires special tools and thorough knowledge of reconditioning techniquesFollow the instructions provided in the cylinder head service tool kitNOTE: Valve seat width and point of contact on the valve face is very important for proper sealingThe valve must contact the valve seat over the entire circumference of the seat, and the seat must be the proper width all the way aroundIf the seat is uneven, compression leakage will resultIf the seat is too wide, seat pressure is reduced, causing carbon accumulation and possible compression lossIf the seat is too narrow, heat transfer from valve to seat is reduced and the valve may overheat and warp, resulting in burnt valves12When thoroughly heated, place cylinder head on blocks of wood which will allow the old guides to be removedUsing valve guide driver, drive guides out of the cylinder head from the combustion chamber sideBe careful not to damage guide bore or valve seat when removing guidesPlace cylinder head on cylinder head table