1997 Yamaha YFM600FWAK ATV Service Manual, Page 129Get this manual
VALVES AND VALVE SPRINGS
VALVE AND VALVE SPRING REMOVAL
1.Check: Valve sealing Leakage at the valve seat -) Inspect the valve face, valve seat and valve seat widthRefer to "VALVE AND VALVE SPRING INSPECTION"
Checking steps:
Pour clean solvent CD into the intake and exhaust ports Check that the valve seals properlyThere should be no leakage at the valve seat