I tried a zama carb, the one the saw came with one of the 650 sawsand got about the same result. I did install a velocity stack and a much larger volume muffler. I did not measure the ring gap. The leak down is very slow, if that means anything. It does not want to idle down real slow. It could be the rings you're right


A 20x8 turns a little better than 7K. The front oil seal seems a bit tight, it squeaks. It is brand new though. I can't imagine that tiny bit of drag would make a difference. I put it in my Big Bee today. I'll fly it and see how it goes. The parts are a mismash from different engines so maybe it just needs to break in a bit?

I was expecting about 5-hp. I was thinking I could do as well as a G62. I appear to be getting about 3-HP That is from this calculator.

http://personal.osi.hu/fuzesisz/strc_eng/index.htm

I had visions of this engine being a real powerhouse. Apparently not, no big deal. I got a more than the CS-510 so that is good. Actually, calculating it out I have more than 30% extra horse power. Since I went to an engine that is 30% bigger, I guess I did OK.