RE: 90 sized engine recommendation
I have an ASP 1.08 2 stroke on the front of my U-can-do .60. The original carb was replaced with an O.S. carb... it hovers at a little over half throttle, will accelerate straight out of said hover nicely, knife edge loops (when I can manage to make my thumbs give the correct commands, anyways) and has been super reliable and easy to start.