Backfiring Brute Force ... 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 . .

[roamer9562]

I would say more than likely if he changed the filter kit and did not re jet that is probably causing your problem.... 90% of the time when you do filter kits and pipes you should always rejet.
I would try this first and foremost.... could save you some money in taking it in for service.

Roamer

[winot01]

Well I cant help too much, but my dad has an 05 brute force 750. Ever since it was a couple weeks old every time you mat the throttle and back off it will backfire. The quad is not stock, 27" ITP mudlites, and a stage 2 clutch kit, but he has not touched the air filter, carbs, or engine. One of my friends says it could be a bad spark plug? but I have no idea.