My 06 Kawasaki 4 wheeler. Backfires when light switch is on going down highway. Is it battery related ?

It is is firing out of the carb and the exhaust, the timing must be off, but also slipping. Is the flywheel tight?

https://www.google.com/search?q=1984+kawasaki+klt+250+backfiring+problem

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Brute force backfire problem - YouTube

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www.youtube.com/watch?v=VFxGBYoVFqk
May 5, 2013 - Uploaded by gubba1957
I bought this 2006 750 it had a backfire problem when I bought it so I cleaned ... 2005 Kawasaki Brute Force 750 - Stock Exhaust Modification ...

go back and chec for proper grounds or wiring flaws--a clymer manual has diagrams and rebuild details--is battery at 12.6v--a coil ignition cant have less then this--are terminals tight enough

what engine size?
the PCM runs the show, and its bad. or wires bad to it.
your car has PCM regulator.
no charge battery light.?

1: takes a good battery and battery cables and lugs cleaned.
2: test the altenator, odd how 4 of yours all tested good but you replaced it 4 times, get it tested if good, its good.
3: then check that the charge .battery lamp works. if the lamp works
that means the PCM thinks that charge system is bad.
if the wires from the rear of the alt, to the battery red and Gy wires
are good all the way to PCM then the PCM is bad.
the big wire on rear of ALT , on one car had a bad lug. #6 wire.
he replaced the ALT 6 times. all wasted effort.
inspect the wiring first. that is free, and is simple fix.
and if the ALT casing is not grounded, all bets off.
same with battery minus lug not good, on BOTH ENDS>
one guy had his battery lug moved to frame, (wrong)
and this never worked.

kinda sounds like engine is out of time

The float in the carburetor is possibly sticking. have the carb cleaned or run some carb cleaner through it.

If the unit runs normally after it starts it is probably a defective coil that isnt changing timing relative to crank speed. It is running advanced even at slow speeds and that is the backfire. You could also have a slightly bent flywheel key. This is what sets the primary timing so it is always a good idea to check it when you have the engine cover off!

Remove skid plate on bottom of differential by removing 3 small bolts on bottom. Jack up 4 wheeler support 4 wheeler where the right side the break side will be off ground and nothing is connected or against axle. take off lug nuts remove tire take off center cap and remove cotter pin and axle nut remove break drum remove 4 bolts in center remove all things connected to right half of axle housing everything to the right of differential remove 4 bolts that connect axle housing to differential remove axle housing right side then remove axle

recheck the timing, valve and ignition both.

good chance u have a bent rod, bent valve. Need to take to shop to get checked out.