Yamaha F100B F100C Outboards Factory Service Manual, Page 125Get this manual
Cylinder head 3Measure the camshaft journal diameter and cylinder head journal inside diameter dReplace the camshaft and cylinder head if out of specification
Checking the cylinder head
1Eliminate carbon deposits from the combustion chambers and check for deterioration2Check the cylinder head warpage using straightedge and thickness gauge in five directions as shownReplace if out of specification