Backfiring Brute Force 750 ... Help QUICK!!!!

[Quad18star]

What would cause an 05 ( Maybe 06) Brute Force 750 to just suddenly start backfiring ??

My buddy has a BF 750 that is practically brand new and he started it up the other day and it's been backfiring like crazy .

He just relecently added a K&N filter and did not rejet , but he rode the quad for a few days after the filter change and had not had a problem .

The only thing that he can think of , is that he went into the clutch area to do some cleaning and may have hit a sensor or something ( if there's any) .

We need help FAST . We have a big ride planned for this upcomming weekend , and he can't bring it into the shop before next week . .

[ryedogg racing]

Loose Exaust, Hole In Exaust. Does It Do It While Slowing Down. Also Try To Raise The Idle A Little Without The Belt Grabbing.ITS ALSO RUNNING LEAN WITH THE K/N FILTER THEY COME FROM THAT FACTORY A LITTLE LEANED OUT.
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[Which 450?]

The 05's come from the factory lean. Is the 4 wheeler still running full speed? is the belt light on? there is a switch in the belt cover, it is a toggle switch, when the belt gets loose it will hit the toggle switch, pull the cover back off and make sure the toggle switch is pointing toward the rear of the quad.

[GOTFEAR]

One of my riding buds has the same thing he piped it and K&N filter we are getting ready to put a jet kit in and chang his pilot jet a little good luck.

[quailbuster]

Hopefully he has it figured out by now. Just going through lookin at a few posts. Sounds like he tripped the belt sensor on top of the belt housing.