Rick, there are several sizes of these motors used on mini bikes and go karts. I am running a 580 on a vintage kart and it does pretty good.
One member here has a restored race version with two 820's on it. Go Kart and a few other MFG used them as original equipment.
As you might imagine, they're all about RPM, not torque. So correct gearing is essential, but once on the pipe, they do very well. If you have strange shafts, like 9/16, you have to worry about getting clutches for them.
But you can deal with Max Torque directly, and he'll hook you up. Cool motors, and I wish all my bikes had them.
