1987-2009 Yamaha ATV YFM350X Warrior Raptor Service Manual, Page 56Get this manual
COMPRESSION PRESSURE MEASUREMENT 1Check: Valve clearance Out of specificationAdjustRefer to the tIIVALVE CLEARANCE ADJUStI TMENT section
2Start the engine and let it warm up for several minutes
3Stop the engine4Remove:
Spark plug
5Attach:
Compression gauge