400ex FCR Carb Jetting

[thess92]

i have a 400ex with a procircuit t-4 exhaust, uni filter, and big gun rev box stock bore and stock cam. i had recently bought a 39mm fcr carb and i installed it and it runs good wideopen but when i let off the gas from being pegged it bogs down. great throttle responce but it spits and sputters and cuts up unless its wideopen. the main jet is a 160RD and the pilot jet is a 52

[2muchquad]

try raising the clip on the needle a notch to lean it out a bit,sounds rich

that carb is the same one that i have mine came off a 06 450r im running a main is 150 and the pilot is a 50. mods are 440 kit 12.5:1, ported head, stage 2 hot cam,hmf full pipe so i would say your to big on your jets. it took me a week to jet it jetted right. we run 1/8 mile drags 8.73 @ 75mph