I need help/advice!!

This has happend to me two times: When is start the machine up it backfires so the carburators pops off???? what is happening?? i was tonigth in the middle of the woods!!!

Can somebody please tell me what is going on and what should i do to get rid off this problem(the screws on the carbs was tight!)

 

The carburator itself popped off or the boots popped off?? It is most likely a jetting issue.