Thanks again Bruce, and thanks very much for the insight there Grumpy. It seems these little engines may not have as much scope for pepping up as I'd hopped. Given the originally ultra low state of tune and .... build quality... (the innards of my old Victa motors looked light years stronger and better made), plus the fact that they're supposed to run with a govenor I shouldn't be surprised. I do however intend to continue with these little guys in their application... no rush and it's all good fun. I really appreciate you gents taking the time to help me out.
Cheers again.
