Sputtering can be caused by junk in the carb, get an inline filter. there is a reverse rev limiter.

Now, do you have sputtering at take off or more like a bog where it feels like it is trying to take off in third gear (I know its an auto)? That would indicate that one of yer rollers has a flat spot and the clutch is not operating properly. Rollers are not included in a clutch kit but are available from Suzuki.

 

i think all you have to do is rejet. since it runs fine with the choke on then you should just be able to rejet and it will work fine.

 

Maybe your belt is slippping, and when you choke it it raises the idol up and allows the belt to engauge quicker.

 

If it is new, take it back to the dealer and have him fix it. Won't cost you nothing[img]i/expressions/face-icon-small-smile.gif[/img]