Finally got a chance to fly it on Sat. The timing was the problem. The SV50 screams with a 22x10. I might try a 23x8 to slow it down some on final. All it needs is a little breaking in and carb adjustments as I go along. Starts great and the 74in Extra will leave the ground at half throttle. Seem like they should put the timing check in the instructions that come with the engines. Something like: "Our manufacturing methods are sort of hit-and-miss. Please adjust the timing before running. We hope it falls somewhere in the adjustment range of the switch." Actually I had made a mental note to check it, but when it halfway ran on the ground, I let it go.