I was thinking of tightening the wheel collars just enough to cause some friction. Poor mans breaks. The engine has been running better with more break in and I have been slowly but surely adjusting the low speed needle. I think I'll put the bigger prop back on to slow the engine down a little. I had a 14X6 on it and I think that is part of the problem, I'll go back to the 15X6 and see if that works. Thanks for your help.