I could actually build this bike. It wouldn't look exactly the same as it does here, but i could come very, very close.
To actually get power to the back wheel I'd have to use a hydro-static drive. A system which would make the bike very energy efficient as the pump and motor would form an hydraulic Infinitely Variable Transmission. This would allow the bike to accelerate through increasing the flow rate of the pump rather than the revs of the engine.
With a properly tuned V-twin, the bike could easily achieve 2ltr/100km fuel economy (117.6 mpg), without sacrificing anything.