In addition, ready-made manual valve holders are available for sale.
Fig. 5.13. Valve grinding device: 1 – metal rod; 2 – rubber hose; 3 – screw clamps
If they are not available, you can use a device made according to the drawing (Fig. 5.13).
In addition, you will need: lapping paste, kerosene, a weak spring with an outer diameter that passes through the valve seat hole.
1. Clean the valve from carbon deposits.
2. Apply a continuous thin layer of lapping paste to the valve chamfer.
3. Place the pre-selected spring on the valve stem and insert the valve into the guide bushing from the combustion chamber side, lubricating the valve stem with a layer of graphite grease.
Note: Graphite grease prevents the abrasive from the lapping paste from getting into the guide bushing holes and makes it easier to rotate the valve during lapping.
4. Place a valve lapping tool (or, with some tension, a rubber tube to connect the valve to a reversible drill) on the valve stem.
5. Turning the drill on at minimum speed (in reverse mode) or rotating the device (in the case of manual lapping) alternately in both directions by half a turn, lap the valve, periodically pressing it against the seat, then loosening the pressing force.
6. An external sign of satisfactory lapping is a uniform matte-gray color of the valve working chamfer…
7. …and valve seats in the cylinder head.
8. After grinding, carefully wipe the valve and seat with a clean cloth and rinse to remove any remaining grinding paste. Check the valve for leaks by installing it with springs and crackers in the head. Then place the head with the combustion chambers facing up, plug the spark plug hole and pour kerosene into the combustion chamber. If kerosene does not leak into the cylinder head channel within 3 minutes, the valve is leak-proof.