Brand new zongshen 250cc running crap!

[Brizz125]

Bought the bike bout week ago, starts fine but symptoms are: it runs rich, wont rev past like quarter throttle, and crakles and pops and stuff.
I played with the screw on the side of the carby, thinking it was the idle..
Have i totally stuffed the mixture?
Any help much appreciated

 

[lo-cou]

ahah yeah just get some one who knows what there doing to tune it,aslong as you havnt gone way too lean motor will still be fine,i got a atomik pro-x 250cc aswell,bloody awsome bike,superb ride quailty compared to little brother,and the smoothest power curve,very nice bike to ride