What causes backfiring

[Haskins1111]

I have a 85 accord for a commuter car and it backfires when i shift. It is not to loud and doesnt happen to much after it has warmed up. Just wondering if it is an easy fix. Vehicle info- carb., 5 speed, new plugs and wires, and the backfire is from the tailpipe.

 

[Gumby]

Often an exhaust leak can cause a backfire like the one you describe. When your car is cold it's getting unburnt fuel into the exhaust when you shut your throttle off quickly from high RPM, the leak provides oxygen.