Yamaha F100B F100C Outboards Factory Service Manual, Page 100Get this manual
Power unit
Valve clearance: Intake e: 0.20 0.03 mm (0.008 0.001 in) Exhaust f: 0.34 0.03 mm (0.013 0.001 in) 8Adjust the valve clearance if out of specificationLoosen the tensioner bolt 5, and then remove the timing belt 6, driven sprockets 7, camshaft caps 9, and camshafts 0
6Turn the flywheel magnet 360 clockwise
CAUTION:
Do not turn the flywheel magnet counterclockwise, otherwise the valve system may be damaged7Check the intake valve clearance for cylinders #3 and #4, and the exhaust valve clearance for cylinders #2 and #4Adjust if out of specificationEX IN