2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 79Get this manual
ADJUSTING THE VALVE CLEARANCE
EXAMPLE: Original valve pad number148 {thickness1.48 mm (0.058 in)} Rounded value150 dLocate the rounded number of the original valve pad and the measured valve clearance in the valve pad selection tableThe point where the column and row intersect is the new valve pad numberNOTE: The new valve pad number is only an approximationThe valve clearance must be measured again and the above steps should be repeated if the measurement is still incorrecteInstall the new valve pad and the valve lifter 2NOTE: Lubricate the valve pad with molybdenum disulfide oil Lubricate the valve lifter with engine oil The valve lifter must turn smoothly when rotated by hand Install the valve lifter and the valve pad in the correct place_