It depends
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,
Check the air filter, fuel filter. Either of these easily blocks on mower.
You probably have a bad bearing.
Sounds like the engine heats and the ignition fails.
not secured properly, user sockets
sheared flywheel key. youtube has vids... type in mower cord backfires & you'll see instructions on how to fix it.
No. They sputter for a few seconds then quit running.
running lean can cause your 400ex to backfire ..if it backfires on deceleration its lean ...if it pops on acceleration its running rich.====carb issues
because it is a worthless piece of junk!
Fuel tank cap vent is plugged.
Depending on the mower some have belt driven generator . But most have a alternator under the fly wheel . It might also be a faulty rectifier. Hope this helps.