The McCulloch and similar mag engines are very low powered. I ran a 16*8 on my 83" WOT (very light, sport not scale) and it was just about enough to fly it. It's got a DL50 on a pipe now and it's like a big shock flyer in 3D

A 105" 18lb (EEEEK!) (Double EEEK! 18lb!!!?) Cub would be better on a 40cc, preferably with electronic ignition. The 26CC aircraft engines do have more than the stock trimmer conversions, but I don't think that will convert the plane you have from 'lumbering' to 'sprightly'.


Why gas? Usually the best tickover, less oily mess and more interest [8D]