2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 81Get this manual
ENGINE NOTE: If valve guides are replaced, valve seats must be reconditionedRefer to the "Valve Seat Reconditioning" procedureValve Guide RemovalInstallation 1Remove all carbon deposits from the combustion chamber, valve seat and valve guide area before attempting to remove valve guidesCAUTION: Carbon deposits are extremely abrasive and may damage the valve guide bore when guides are removed2Place new valve guides in freezer for at least 15 minutes while heating cylinder head3Heat cylinder head in an oven or use hot plate to bring cylinder head temperature to 212 (100 C)CAUTION: Do not use torch to heat cylinder head or warpage may result from uneven heatingHead temperature can be checked with pyrometer or welding temperature stickFollow the manufacturer's instructions provided with the valve seat cutters in commercially available valve seat reconditioning kitsAbrasive stone seat reconditioning equipment can also be usedKeep all valves in order with their respective seat
Combustion Chamber
Clean all accumulated carbon deposits from combustion chamber and valve seat area with soft wire brush