Tired of pedalling then this is the answer if you still like riding a bicycle. Not quite a motorcycle but lots of people like these engines. Although they're designed for helping struggling cyclists, they can be used for various other things, such as powering a small boat or driving a generator. The manufacturers advertise this engine as 80cc, but it's actually only 69cc.
type - air cooled 2-stroke
bore - 47mm
stroke - 40mm
capacity - 69cc
power - 2.5kW (3.3HP)
engine speed - 5000 rpm
Compression Ratio - 6:1
gear ratio - 18:1
weight - 12.3kg
length - 420mm
height - 415mm
width - 180mm
Speed limit - 30 km/h