ive ridden them, no offence but they are really slow, not much acceleration and they hardly go over 30 kmph, 40 if ur sons riding it, they are really bad at braking and turning. And you will also notice that they are very very unreliable, every few days u will have problems witht the engine, and later on a big problem with the pull start. They are pretty cheap though about 8000 rs after shipping to canada, 160$. They shud be about 4-6k in china then. Really good for the price.
Image this bike welded on to a cg125 engine, i am not sure it will fit but it is possible. Not to forget the bike will be way off balance if a larger bike engine is fitted into it
