Valves should be lapped with racing 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 frequent lifting and continued rotation of the lapping valve.
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: loosely insert the valve; by filling the combustion chamber with fuel that must not flow out of the valve guide. Otherwise, continue the lapping process.