It might be overfueled but it also might be just that when you turn the key off the motor runs on a bit and puts fuel into the hot exhaust and it ignites it and makes it backfire.
The unburned fuel is igniting inside the muffler. Let the engine run at idle for 30 seconds before turning the key off.
Timing is off.
It's lean. Could be something plugged in the carb.
The chain can not backfire. If it is installed off time it can cause a backfire, which could conceivably damage a starter.
it doesn't or it shouldent'
well it all depends on when it is backfiring most of the time on start up if it does back fire then it prob because when you turned it off you had the rpms high and sum gass was mostlikely left in the carb
Yes.
The timing is off.
backfire timing off
Timing is off ...
check the timing....
timing is off or firing order is off