RE: Shike 10-15 engine?
How about an MVVS .15, set up for rear exhaust (the way that engine was designed for)...? A lot lighter than the .21, and very capable (for its cost) when you swap the carb for a venturi... And give Morris Hobbies a call to see if he has any of those .15 Rossi pipes left... they are a direct match...