@@johncabell5841 I first used a 3hp Briggs and Stratton with a mikuni carburetor. That fits with no cuts in the frame and I just drilled holes into the battery tray and mounted it there. You should be fine with the sx500 frame but you wont have rear brakes as you have to swap the back wheel around. I also had to buy a special tool to remove the original free wheeling hub. I hope this helps!
