No 50cc or 2-strokes here....
99% are 4 strokes and the smallest is 100cc.....
Most common are the "underbone (cub)" types... they are cheap, chain driven, very low fuel consumption, fast, and lots of after market accessories...
Here's one example... the Kymco Visa R 110cc... at $880.00, need I say more?
and Stig, the seat is really comfy...