I think I have the Solution!
The tors system, when hooked up incorrectly, will allow the engine to idle, and to rev slightly (i had the same problem)
This system is designed to cut the spark if some part of the throttle linkage becomes stuck or jammed open.. Check the wires on the sensor on the thumb throttle, and on the linkage above the carb..
If you want to disable it, there are kits.. But do it at your own risk, this advice is to help you get it running, but get a kit to take care of it once u get it running..
If you have the 03 or later model, there are 8 wire coming out of the CDI box.. the ignition box behind the headlamp. There are two thin striped wires, thinner than the rest that is.. If these two wires are left in open air, it will idle, but wont rev, connect one to the chassis, and it will run normally, dont remember which one though.. If you have the older model, with two boxes, then Im not sure what wires you need to change, but it involves grounding or not grounding wires that go from the ignition box (the one with the orange wire that goes to the HT coil) to the TORS box..
Hope this helps..