I run a China girl 66cc engine sometimes referred to as an 80cc. At the moment, I have substituted the bearing with a bronze bush. It runs pretty fine, but I can feel the friction in the engine and it is increased as compared to bearing. I use a mixing ratio of 1:25 hoping that it would improve performance of the bearing from the the 1:30 I was using before. The downside of 1:25 is reduced engine power and more smoke.