Yamaha F100B F100C Outboards Factory Service Manual, Page 111Get this manual
Timing belt and sprockets NOTE: Do not turn the camshaft when loosening the driven sprocket bolt2Check the drive sprocket and driven sprockets for cracks, damage, or wearReplace if necessary
Flywheel holder: 90890-06522 6Remove the nut 1, drive sprocket A, retaining plate B, and Woodruff key CS60C5220
Installing the sprockets and timing belt
1Check that" marks and on the driven sprockets are aligned, and then tighten the bolts 2