About 6 weeks ago an oportunity arose for me to buy an F80b. (generic china girl) Even though I didnt even own a bike at the time,(very unusual for me!!) I brought the kit anyway. Over the next week I started researching websites and stumbled upon MOTOREDBIKES.COM forum,¦....before I knew it, my motor was in pieces, being given a few basic modifications!!! I even managed to scrounge up enough parts to put together a ride! So far I have given the stock nt carb a port & polish, slightly enlarged the jets by hand with a bit from a dremel, homemade highflow air filter using aquarium filter,larger fuel line for increased flow, honed out the inlet/exhaust manifolds, shaved about 0.5mm from the head using the mirror+sandpaper method then made a new head gaskit from coca cola can. NGK spark plug .¦..so far.. Ive riden a few stock standard straight out of the box motoredbikes and i'd have to say there is absolutely no way I could have left mine stock!! The extra power and speed is incredible!!!. After the constant tinkering Ive got her running sweet. The way it revs out at WOT/top speed is a little bit scary to be honest!! But when I do rev it out like that its never for very long, Im a bit worried it will blow apart between my legs when its revving off its head like that !!! THANK YOU ALL for the advice and the ideas for mods. My bike would not even go half as fast as it does if it wasnt for this forum. Sorry about the long rambling post, but I love my bike. I wish I got one years ago!!!