Re: rear wheel not engaging
Maybe bad wiring?
I know I didn't ground my white wire properly, thought I had to connect it to something; boy was I wrong.
I would pedal, let go of the clutch, hear the engine running, stop pedaling, engine dies. Throttle would make a revving noise but only a small one which did nothing. Engine would only keep running if I continually pedaled.
If this sounds exactly like yours, possibly something to do with the white wire possibly making contact with something when it shouldn't, should be isolated (I taped mine up).
If this isn't it, I guess it would be something mechanical inside and my only guess is that which ever part of the engine that spins the small sprocket which turns the wheel is damaged or not functioning as it should be; thus engine powers, but unable to turn the sprocket to turn the wheel.
But you saying you can't throttle makes me believe this is more the case, or the white wire problem, as my guess is, even without throttle, your bike should just idle, not die; just a guess.