2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 91Get this manual
ADJUSTING THE VALVE CLEARANCE 6.Remove: Timing plug 1
7.Check: Valve clearance Out of specification AdjustValve clearance (cold): Intake: 0.100.15 mm (0.00390.0059 in) Exhaust: 0.150.20 mm (0.00590.0079 in) Checking steps: Turn the crankshaft counterclockwise with wrenchAlign the "I" mark on the rotor with the stationary pointer on the crankcase coverWhen the "I" mark is aligned with the stationary pointer, the piston is at the Top Dead Center (T.D.CNOTE: When the piston is at the Top Dead Center (T.D.C on the compression stroke, there should be clearance between the valve stem tips and their respective rocker arm adjusting screwsIf there is no clearance, rotate the crankshaft counterclockwise one turn