Thank you all for your input and suggestions. I have it running somewhat better but the lack of any means to adjust things makes it hard to make any appreciable changes. One of the main problems with this engine is the very marginal compression stroke. As I said the compression comes from one cylinder moving faster that the other so even perfect parts still make for marginal operation. I have made and remade parts for this engine several times. The pistons/rings leak no matter what I do. They even leak with o-rings but with o-rings it develops enough compression to at least run somewhat consistently. I have made at least six sets of pistons and 10-12 sets of rings and the results seem to be pretty much the same no matter which set of pistons or rings I use. Yes I have made rings using the Trimble method as well as other methods. I have also tried several carburetor designs as well as RC carburetors. Sometimes I am just too stubborn for my own good. I should have given up on this thing a long time ago.