@ Pe

All the engines I've flown where mounted inverted, could that be the difference?

The only engines that I can compare them to are the RCS 140re 22cc, and SPE26 of about a year ago. I flew the SuperStar with the SPE-26, then Larry put the LS-26 in it, it seemed to have more power with the LS-26. Another guy had a RCS 140re 22cc motor in a SuperStar it had more power and seemed to be a better motor all around, but it cost $425.

I've found the same thing with the Chinese engines, quality control is lacking. With the three engines we have flying at our field there have been no issues, other than the lack of a choke.