RE: GP Waco?
When it worked, it was a lovely engine. However, Ifound it very unreliable, constantly required re-tuning of the high end.
It is a very common issue for this specific engine (The FG-20) and much is written on it in different forums.
After very long battle with it, I had enough and this is why Ireplaced it with the MVVS.
One only other thing is the power. Iwill rate this engine as a ~1.10 and not a ~1.20 engine.
Because Ido like the engine (the sound is fantastic), Ididn't give up and I asked a friend to modify it to take Walbro carburettor.
Few people on the net did it and reported that it solved the problem.
Ithink that this engine was victim of too small and fiddly carburettor (the original which is similar to glow fuel carburettor).