Stick with the .61 and throw a 12-4 prop on it and there is your extra thrust. If you have a relaxed flying style and are careful, the ultimate bipe will fly fine with the OS .61. Keep the rates on your radio LOW. I flew this motor in a Super Stick ARF and it was missle.[X(] My friend I was teaching thought it would be a good second plane. It turned out to be more than he could handle on his own and it still is not rebuilt.[]

I would recommend the Lanier Dart/ARF. I had one set up as a tail dragger and would do all the basic and not-so-basic aerobatics with a Super Tigre .61 and 12-6 MA prop and it was cheap! I think you can still get them for 59 bucks. They have semi-semetrical airfoil and are low wing and they will fly well slow or fast, whichever you prefer.