Ok, I have a little update, I bought 2 400 permax motors and 2 graupner universal joint couplers. Everything seemed to go together easy, too easy. I ran the boat, and the couples keep slipping on the motor. It will run for about ten minutes and then the couplers start to slip, then I have to retighten them again. The hole in the coupler seems a little larger than the shaft of the motor, so I think the coupler is actually vibrating loose. Another thing that doesn't seem to help is the dinky little flat head screw in the coupler that I can hardly get tight enough to hold on to the motor with. I know the coupler is unbalanced, cause the boat buzzes like oprah's vibrator. Should I get new couplers? I spent 20 bucks on the couplers and really dont want to spend 20 more, any suggestions?