300ex jetting help

[sneekypete]

I have a 2000 300ex with a fmf mega max exhaust and k&n filter i'm sure someone has a similar set up it backfires and pops on deceleration and I can't run it full throttle because it hesitates. does anyone know what size jets I should try? I am about 10 feet above sea level.

[fmftrx300ex]

Are ur current jets stock? if so u need to order some jets, go bigger then stock or buy a jet kit, if you go on fmf's website they have a "jeting center" it gives you tips and ideas on where to start

[sneekypete]

yes the jets are stock I can't give it full throttle in fifth because it ain't getting enough fuel i would guess. will a larger jet make it faster? with the extras i have on it i think it should be faster then it is. i went to the website and i didn't think they were much help thats why i posted it on here.

[300exboy #15]

if u live at a low altitude like sea level to 2500 feet then u can run a 135 with now air filter box or a 130 with air box lid on u just rlly have 2 play with it

[JohnT_98300EX]

I run an FMF Q2 and 4 1 inch Uni filters in the air box lid. I went up to a 128 main and kept the stock pilot and needle setting. This info came from the FMF website and seems to work fine.

[bwamos]

I use to run the FMF Performax full pipe (predecesor to the MegaMax) w/ a K&N Filter w/ vented airbox lid.

I ran 132 Keihin Main (w/ 9 disks on the pipe), Needle raised 1 slot. And a/f screw turned out 3 turns from seat. If you get backfiring up the pilot jet to a 40 and you'll end up around 2-3/4 turns out.