Valves should be lapped only with fine grinding paste. A rubber suction cup is installed on the valve plate for the necessary rotation. The formation of grooves can be avoided by frequently lifting and then uniformly rotating the valve in different directions during the lapping process.
Attention! After lapping, the grinding paste should be carefully removed. The lapping process can be checked by the appearance of the working surface or by using fuel.
Insert the valve, fill the combustion chamber with gasoline, fuel should not leak from the valve guide, otherwise repeat the grinding.