Motor is popping back through the carb... Help!

If the intake is hung open, it will not pop. The pop is the cylinder actually firing. The intake valve being hung open would bleed off cylinder pressure and result in a miss and there would be no pop. Let me ask you this Tom, is the pop very repititious when you increase the throttle? As in a cylinder firing every revolution? If so, dollars to doughnuts, there's an exhaust valve staying closed for whatever reason. Why don't you give me a call tomorrow and we'll talk about it?