2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 92Get this manual
ADJUSTING THE VALVE CLEARANCE 8.Adjust: Valve clearance
Adjustment steps: Loosen the locknut 1Insert feeler gauge between the adjuster end and the valve endTurn the adjuster clockwise or counterclockwise with the tappet adjusting tool until the proper clearance is obtainedTappet adjusting tool: PNYM-08035, 90890-01311
the adjuster to prevent it from moving and then tighten the locknutLocknut: 14 Nm (1.4 kg, 10 ft lb)
Measure If
the valve clearancethe clearance is incorrect, repeat the above steps until the proper clearance is obtained