Valves should be rubbed with a fine grinding paste. To ensure the necessary rotational movements, a rubber suction cup is used, put on the valve stem. Scratching during lapping is prevented by frequently lifting and continuing to rotate the valve during lapping.
Attention: After lapping, carefully remove the grinding paste.
The lapping process can be controlled by the appearance of the surface or with the help of fuel: freely insert the valve, fill the combustion chamber with fuel, fuel must not flow out of the valve guide. Otherwise, continue the lapping process.