What you describe sounds like a lean condition. Check to make sure the choke isn't pulling off too early.( is your mixture ok otherwise?) Another thing that can cause the carb to "pop" is ignition timing being too far advanced, but I doubt that this is an issue at this point.
If this pop also occurs when warm, then perhaps your lean condition can be caused by a vaccum leak. If it occurs upon acceleration, then I would guess poor performance from the accelerator pump. (just a few more thngs that came to mind)
Hope this is helpful
[This message has been edited by Larry Delor (edited 01-06-2000).]