BOG and Back Fire

I put a FMF exhaust on my 07 wr450f. It helped with power and sound, but I have a terrible bog. Any ideas?

Need a bit more info mate, is it bogging at 1/4, 1/2, 3/4 full throttle?

Have you done the usual throttle and airbox mods?

Almost certainly need to re-jet but you need to give us much more information.

when I put a fmf pipe on my 07 I found out my accel pump was hardly working . you should check it . you could do the o-ring mod . Or get a adjustable leakjet . I got a rd powerbowl ,it fixed a few issues with the carb / accel pump + you can tweak it on the fly , I got sick of pulling this bike all apart just the adjust the carb

I put a FMF exhaust on my 07 wr450f. It helped with power and sound, but I have a terrible bog. Any ideas?

It gave you a swamp and mud....Those FMF guys think of everything....:thumbsup:

{you are lean somewhere in you jetting range...call FMF and tell them to make it better}

as soon as you open the bike's air flow up, you need to give it more fuel to compensate.

Likely, you'll need a bigger pilot jet and main jet.

If your idle is rougher at startup, that's one indication, the bog means you're not getting enough fuel, the backfiring on decelleration is another sign.

Check what you got for jets, go one bigger on the pilot (that usually fixes 0-1/4 throttle), if your main is a 165, there's a 168 and a 170 available, I'd get both and see what's better. You may have to go even bigger, but that usually does it.

You'll have to retune your idle speed and fuel screw, so a ZipTy screw is a nice addition.

I also turned my AP screw 1/4 turn in and it made the odd bog I was experiencing completely go away.

I put a FMF exhaust on my 07 wr450f. It helped with power and sound, but I have a terrible bog. Any ideas?

Have you taken off the ais? Mine backfired on decel until I took this off and now no problems:thumbsup:

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