07 750 Backfiring on no choke

[ljkimski]

Hey Guys new here, been to all the local shops and no one can help me with my 07 750 Brute. when its on no choke and I rev it up it backfires thru the carbs BAD, when I have the choke on 1/2 or 3/4 it runs excellant with no hesitation at all. I ve had the carbs off and they are clean with a slight coating of grease. Is it that I am trying to run it without the air box on ?? went thru another tank to see if it was my pump or lines and it still wants to back fire. Been looking at all the forums and not sure if jetting could be a problem also but, every thing is CLEAN any help would be greatly appreciated, Lenny

[NMKAWIERIDER]

Welcome.
1. You can't run it without the airbox lid on. Its way too lean
2. If it's still lean, check for water in the bowls, Cracked boots, tight valves or weak fuel pump.
3. If all that checks out, try running it with the tank cap loose. If its good, replace the vent check valve.

[DLB]

Welcome Lenny. I think NMK covered all the bases. Let us know what you figure out.

[rmax]

if all that fails you might want to put an electric fuel pump on it had a simular problem awhile back with a bbk i built