Spark plug wires are installed incorrectly, or the enigne is out of time. Too much fule that is not being combusted in the engine. Fuel gets into the hot exhaust, then ignites.
Unburned fuel in the exhaust system causes the backfire from the exhaust pipe.
I think you are hearing pressure pops. Not a backfire.
unburned fuel in the exhaust ignites
a backfire is caused by incorrect timing or not enough back pressure in the exhaust pipe
Too rich-unburned fuel in exhaust.
backfire timing off
A large backfire is most likely caused by a bad spark plug or plug wire. Unburned air and fuel pumped into the exhaust will often be ignited by the other cylinders still burning exhaust gases. Also check your ignition timing, if it is late and you have a rich mixture you can get a backfire. An exhaust leak will let air enter the exhaust under deceleration and cause a "popping" sound.
you must have air leaking into the exhaust system that will cause backfire when you decelerate raw gas goes into the system
you have a leak in the exhaust system lets in air
bad plugs or wires i just had this problem to or it could be a leak in the exhaust
Backfire is an explosion produced by a running internal combustion engine that occurs in the intake or exhaust system rather than inside the combustion chamber,
unburnt fuel wich goes to your exhaust, where because of the heat ofcourse is set on fire and then strikes flame out of your exhaust! sorry for my English