ive had the same problem with a few of mine a few common things are
*idle control screw is right
*the jet in the carb is not blocked
*there is fuel in the filter
*u dont have a air vaccume in ur fuel pipes
What i try if that fails is removing the spark plug and pouring straight petrol down into the bore putting the plug back in and trying it then it can some times force fuel through
i buy and sell these things if anyone would like to e-mail me for more info with any problems please do so dannymcnoltyere07@hotmail.co.uk
thanks
danny
September 2008