2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 90Get this manual
ADJUSTING THE VALVE CLEARANCE ENGINE
ADJUSTING THE VALVE CLEARANCE NOTE: The valve clearance must be adjusted when the engine is cool to the touchAdjust the valve clearance when the piston is at the Top Dead Center (T.D.C on the compression stroke1.Remove: Seat Front carrier Front fender Fuel tank Engine side cover Refer to "SEAT, CARRIERS, FENDERS AND FUEL TANK"