HELP!!! CUB PROBLEMS

If the engine is not smoking and the spark plugs are not developing deposits, then I would suspect the valves are shot. If you have been running unleaded fuel without a lead substitute then you may have destroyed the valve seats. The seats are not hard enough for modern gasoline. If you were running the motor hard the seats will heat up and small amounts of metal will stick to the valve and remove itself from the seat. This will cause pitting on the seats and eventually result in lower compression. I don't think pulling the head and lapping the valves will do enough to clear this up. The block will have to be machined to accept new hardened valve seats. At this point it only makes sense to do a quicky rebuild to ensure proper ring pressures.

I have heard that adding a few squirts of oil to each cylinder before performing a compression test will help diagnose worn rings. I heard that if the pressure increases after the oil is added if proves a bad ring and bore fit. The oil fills the voids left due to imperfections. I have not tried this but it makes sense.

let us know what you find.