To check the tightness of the valve, install it in the head with springs and crackers. Then put the head on its side and pour kerosene into the channel that is closed by the valve. If kerosene does not seep into the combustion chamber within three minutes, the valve is tight.
1. Apply a thin layer of lapping paste to the valve face.
2. Insert the valve into the guide sleeve and attach the valve lapping tool to its stem.
3. Vigorously turn the valve in both directions using the tool, periodically pressing the valve against the seat.
4. An external sign of satisfactory lapping is the uniform matte gray color of the valve face and seat. After lapping, thoroughly wipe the valve and seat with a clean cloth and rinse to remove any remaining lapping paste. Do not reuse the cloth.