2005-2006 Honda ATV TRX500FE/FM/TM FourTrax Foreman Factory Service Manual, Page 139Get this manual
CYLINDER HEADVALVE
VALVE SEAT INSPECTIONREFACING
INSPECTION
Clean all intake and exhaust valves thoroughly to remove carbon depositsApply light coating of Prussian Blue to each valve seatTap the valve against the valve seat several times without rotating the valve, to check for proper valve seat contactHAND-LAPPING TOOL
The valve cannot be groundIf the valve face is burned or badly worn or if it contacts the seat unevenly, replace the valve
Remove the valve and inspect the valve seat faceThe valve seat contact should be within the specified width and even all around the circumferenceSTANDARD: 1.2 mm (0.05 in) SERVICE LIMIT: 1.5 mm (0.06 in) If the seat width is not within specification, reface the valve seat