av8tor. For the fun of it I tried your formula for determining cc. The engine had a stroke of 1 inch and a bore of 1.25 inches. So it looks like a 21cc engine. My measurements were not precise but pretty close I think. So 1.25 x 1.25x 1x .7854 divided by .061 comes out just over 20cc I think unless my math is wrong.

Frank Bowman did not have a ring for that engine. I am sending it to him so he can make one and then add that engine to his list of known engines. Ring will be free. I just have to pay for shipping both directions which is no problem.

I'll report on any improvements when I get the engine back. May be a couple of weeks.

Mike