I was deeply into R/C several yrs back and these engines(Chinese) were just beginning to show up. There were similar engines in use made by various companies Desert Aircraft, 3W etc., that were excellent but pricy engines. Their HP claims were accurate. The Chinese engines were initially problematic, but I assume that probably been worked out by now. The smaller twins while smooth and having a cool factor didn't produce as much power as a good single. Especially the little 40-60cc. Maybe that has changed. All that said, a 80-100cc might make a pretty neat MB. Cooling wise(free air) I just don't see any way it would work out except in a transverse mounting. Some what of a challenge. In an aircraft the prop blast(on the ground) and ram air cools them well. It will take movement to cool them on an MB and at a pretty decent clip. Extended stop and go would not be good. The 2strokes are less tolerant than a 4stroke under these conditions. I'm sure L2 you remember the cooling "eyebrows" I added to the transverse Maytag to catch more air. The longitudinal Maytag still has its cooling fan and works well as is. Not trying to discourage anyone from a build just pointing out some limitations that should be considered. A good running well engineered 100cc MB based around one of these would way cool! I certainly would leave it carbureted though. They run fine that way.