chinese scooter tuning help

Evening all!!!

Hope you can help i have a chinese scooter - gy6, i have had it bored out to 170cc, i have a micron carbon fibre exhaust on it, big valve head, a new race cdi unit, i have a mix of 6gram and 16 gram rollers to give acceleration and top end.

I have a small K+N style air filter on it with also a larger jet in the carb to compensate, it now has great acceleration an will wheelie off the throttle, but gets to about 60mph an feels like its restricted?? anyone have any ideas? Its almost like it wants to go but will not, almost stutters an will backfire???????? Someone said to me remove the vacum feed from the carb an this will help? I can do this but does it sound like a fuel starvation problem???


Any ideas would be greatly appreciated

Thanks in adance!!

Mark

 

Assuming it originaly was a 125cc not a 150cc, the gearing will not allow for much more than that. Like Minor said, finding the right roller weight will improve it but only a certain amount. Even if it were a 150cc wouldn't expect anymore than 65mph out of the original gearing in the gy6 clone engines.

 

I'm guessing your running a standard carb, if so i would suggest a new 30mm or at least re-jet your standard carb.

I have a Chinese scoot with all the mods listed in my at the bottom of my post in the sig section, i can get 72 GPS speed on the flat and around 80-85 down hill.

I still have a new stoker crank to fit by the time i'm done i should be running around 250cc with a top speed of around 95mph.

I have not yet played with my rollers although i do have a teflon variator with 12g rollers gonna buy 1 set lighter and one heavy set and have a play around.

Also try running your standard CDI i have a Bando Race CDI but my bike ran much better with a standard one