I just recently finished an aluminum frame bike build. Works good, but vibrates worse. Went 38 MPHwith shift kit.
Just saw a mini 4 wheeler at another nearby shop being tested by a worker. The motor was smooth and high revving with a pull start. Lots of power!
I just ordered one with trans & auto clutch for $79. free ship. Going to try that route. Might be a lot of work to adapt?
I may have a lot of parts for sale later, if it works.