2006 Honda TRX680 Rincon Factory Service Manual, Page 213Get this manual
CYLINDER HEADVALVECAMSHAFT
CYLINDER HEAD INSPECTION
CYLINDER HEAD
Be careful not to Remove the carbon deposits from the combustion damage the gasket chamber, being careful not to damage the gasket surface, surfaceCheck the spark plug hole and valve areas for cracksCOMBUSTION CHAMBER
Check the cylinder head for warpage with straight edge and feeler gaugeSERVICE LIMIT: 0.05 mm (0.002 in)