a little rich

[csimp3]

hey, my 400ex is running a little rich, i think, it likes to pop and backfire when im slowing down, and if im not wide open, or close to, it likes to bog-down, would i be how lean does it make you quad with the airbox lid off?, think if i went lid-free, it might just lean it out enough?, and could a dirty k&n make that much of a difference, i gotta clean it, but would it prevent that much air from coming in?, thanks

[bwamos]

Bogging at 1/2 throttle:
Sounds like your needle is 1 notch too lean. Drop the clip 1 notch (raising the needle), and see if it helps it out.

Backfire:
Probably from the needle being off.. but once that's changed if it still bogs.. you may be rich on the air screw. Try turning it out a 1/4 turn. Only do this after getting the mid range bog taken care of.

[csimp3]

i give it a shot, thanks