It sounds like either your carburettor is blocked or the mixture screw adjusting.
I`m not familiar with that model but generally the mixture screw on a carburettor has a spring on it.
try undoing it half a turn at a time as you let your choke off to see if it keeps going.
If it need more that a turn and a half, max two turns outwards then it sounds like a carb jet is blocked.(generally you need to turn the mixture screw anti clockwise which will richen the mixture but some vary so keep a note of the original position of the screw.
hope that helps.
jimmy., July 2009
