2001 Yamaha YFM660 Raptor Factory Service Manual, Page 206Get this manual
VALVES AND VALVE SPRINGS
CHECKING THE VALVE AND VALVE SPRING 1.Measure: Stem-to-guide clearance Stem-to-guide clearancevalve guide inside diameter valve stem diameter Out of specification Replace the valve guideClearance (stem to guide): Intake: 0.0100.037 mm (0.00040.0015 in) Limit: 0.08 mm (0.0031 in) Exhaust: 0.0250.052 mm (0.00100.0020 in) Limit: 0.10 mm (0.0039 in)
2.Replace: Valve guide