2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 131Get this manual
CYLINDER HEADVALVE The valve canna! be groundif tile valve face is burned or ba dly worn or If rl
contacts The sear unevenly, replace rhe valve
Remove the valve and inspect the valve seat face The valve seat contact should be within the specified width and even all around the circumferenceSTANDARD: 1.01.1 mm (0.0390.043 in) SERVICE LIMIT: 2.0 mm (0.08 in) If the seat width is not within specification, reface the valve sea t
Inspect the valve seat face for: Damaged face:Replace the valve and reface the valv seat Uneven seat width- Replace the valve and reface the valve seat