That would be a backfire.
Hm?! Backfire = timing issue. Backfire happens when the fuel in the combustion chamber ignites while the exhaust valve is open.My truck does it all the time just no flames. Cause it runs too rich.
What I meant by all the time was when I go fourwheelin and let the motor slow the truck down and have my foot of the gas and the carb loads up and makes it backfire out the pipes.