2001 Edition Yamaha F225A and LF225A Outboards Service Manual, Page 135Get this manual
Cylinder head 10After every lapping procedure, be sure to clean off any remaining lapping compound from the cylinder head and the valve11Check the valve seat contact area of the valve again
Checking the camshaft
b Previous contact width
8If the valve seat contact area is too narrow and situated near the bottom edge of the valve face, use 60 cutter to cut the bottom edge of the valve seatIf necessary, use 45 cutter to center the area and set its width
1Check the timing chain sprockets for damage or wearReplace the camshaft if necessary