My 2008 is back firing more than usual , plug looks good.
What are other causes ?
Think the valves are out of sdjustment ? It seems to do it just whenever .
???
dirt

Is the gas fresh? It could be the valves.

check the Valves on it....

Cracked exhaust coupled with rich mixture when engine brake is engaged. This happens fairly often on BFs.

t doens't matter what the machine is. If an exhaust header is cracked and can suck in air, and if the fuel mixture hasn't burned in the cylinder, a back fire will probably happen.

Cracked exhaust ? I looked everywhere i cant see or feel a crack .
Crap how could that have happened.

How do i check the valves on that model or point me to a link where someone does it .
Shoot i hope im not messin it up .
It back fired 8 times in about 40 miles.
I used to do valves on old VW's and older chevys but im cluless on the KQ but i need to learn and fast.

These guys may have more info.

Quad Crazy

My 450 KQ did that as well...it did it worse when it was cold...I just now remembered...lol. I called and they told me that is was the cold air....cause mine only done it when it was cold....but I adjusted the valves anyway....I have the specs if you need them. Not sure if it was really cold air but it stopped after the valves were correct.

My Big Bear was back firing at times and losing throttle the last time I went to Brimstone and it end up being a combination of stale gas and some debris built up around the filters on the shut-off valve mounted to the tank....I don't know if the KQ's have a similar set up as far as the fuel shut off and all, but I drained my gas...pulled the valve off and cleaned the filters, put new gas in and mixed in some SeaFoam with it to flush anything that might have gotten into the carb and it has cleared up....I also changed the spark plug while I was at it because it had been a while since I put a new one in it.

Mr. Dobber,

I know that you are on the NYROC site and we all know that the NYROC site is the King Quad Guru site. I found this post down there today and though it might help you.

NYROC wrote:

- Backfires. A lot of owners have commented that every once in a while their stock King Quad might give out a loud backfire while decelerating. This is normal. The King Quad with it's EFI and many sensors is able to meter fuel for all operating conditions much more closely and accurately than a carburated motor. Suzuki has taken advantage of this on your behalf to run the motor close to a lean condition in order to maximise fuel economy. You will find yourself getting much better fuel milage on a King Quad than many similar sized but carburated ATV's. The tradeoff is the odd bang. Nothing to worry about (unless you are hunting, I suppose

Follow this link if you want to see it.

http://www.nyrocatv.com/techtip.cgi?viewcat=11&viewtopic=511

Is the spark arrester still in the end of the muffler?

If its has been removed that will cause it to backfire every now and again.

I don't know how fresh your fuel is...but I do know that this gas that you get nowadays with ethanol in it will seperate in a very short time. That will cause one to backfire too.