1998-2006 Yamaha F20/F25 Outboards Service Manual, Page 173Get this manual
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CAMSHAFT AND VALVES
[g The valve seat is too narrow and is near the valve margin
Valve seat cutter set First: 90 cutter Second: 45 cutter
Desired result To achieve centered valve seat with the proper width
[Q] The valve seat is too narrow and is near the