Speaking of Red Max, I was in a shop yesterday looking at them. Looks like Zenoah is the parent company. Its written on the plastic case.

I was told the 25.4 Stihl is a better engine than the 27 cc. I have the Stihl 25.4 that Ken converted and posted pictures of. Never put it in a plane though. It's still sitting on the bench! I had since put a 2 needle Walbro carb on it, but did nothing else with it. One day I will put it in a Kangke monocoupe or a CMP Giles 202.

I have a 23.9 Stihl at turns 8400 with a 16x8, i also have the 27cc and it does not show real good power yet, but i don't think it is broke in yet, only had two tanks of gas run in it.
Ken

What's the weight like on these Stihl conversions?

My 23 and 27 come in a little under 3#
Ken