The valves must be ground with a grinding paste. To ensure the necessary rotational movements, a rubber suction cup is used, put on the valve stem. The formation of scratches during the grinding process is prevented by frequent lifting and continued rotation of the grinding valve.
Note: After finishing lapping, carefully remove the grinding paste.
The grinding process can be controlled by the appearance of the surface or by fuel: freely insert the valve; filling the combustion chamber with fuel, which should not leak from the valve guide. Otherwise, continue the grinding process.