Briggs and Stratton motor bicycle 

Here I've attached a bullet-proof 2hp 4 cycle (no oil/gas mix necessary) briggs motor (under 49cc) and I'm still able to pedal with all gears. In my state I can ride this with a drivers license but no registration is required. Top legal speed is 30 mph. This was a test vehicle to see if I could have my bicycle camper in tow. Unfortunately the 24" rim/big pulley I attached to the rear wheel was not successful in gearing it down enough for steep hills. My motor is old and you still have to assist it going up steep hills, but it's a fun ride. I'm able to pop the belt off the idler wheel when pedaling for any distance which reduces a lot of unnecessary drag.