The engine costs R2200, it is complete kit to fit it on a bicycle. Takes about 2 hours to install. Lots of videos on you tube, there is no engine number and no license required to ride it. Fits on just about any bicycle.
Yup, you can get them up to around 90cc in 2-stroke, and I know you get a 49cc 4-stroke.
The engine capacity needs to be below 50cc, and the donor-bicycle must still have its pedals working. Then it is legal in the State of Florida. No drivers license required, NADA. A lot of guys who have lost their drivers license due to DUI convictions buy the kits so they can still ride to work each day, I see several of these "bikes" each week.
A motor and complete installation kit usually runs around $120 on eBay. Brand new. A used bicycle you can often get free off the side of the road...
I will admit that my arse has itched a couple of times
