Having completed the engine I have had trouble with sealing the valves,but after many hours of grinding I have got them seated.With the carburretor off and covering the ports I have compression,but with the carburretor on I loose compression.I have ground the valve in but I think that the spring is not strong enough and the valve is lifting on the compression stroke and air is exhausting through the air intake.Is a stronger spring the answer or any sugestion will be welcome.
Frank