Tohatsu 4 Stroke MFS 2/2.5/3.5A Outboards Service Manual, Page 103Get this manual
Power Unit 9Apply thin coat of abrasive compound on the overall valve seat contact area, and turn valve lapper (commercially available item) while tapping valve
CAUTION
Perform the work by taking care not to allow abrasive compound to adhere to valve stem and valve guide Use finer abrasive compound to finish When changing abrasive compound to finer one, remove present one completely After completion of lapping, wipe off the compound and then clean