need help! 400ex midrange cutting out

[grant.uirsmo]

on my friends 400ex we just installed k&n air filter w/ outwear, t4 slip-on, and dynojet kit, and we retained the airbox and lid. we followed all jetting instructions for our applications and altitude (200ft): using a size 170 jet, 3rd grove on needle, and air/fuel mixture screw 3 turns out from closed. when riding the bike it shortly cuts out about half way through the revs in the midrange, then catches up and climbs more. this doesnt happen every time, and usually happens in either 2nd or 3rd gear.

please help
thank

edit: and a brand new plug was added, hottest ngx we could get

[key4202003]

does it hickup or sputter several times? eather way it sounds like its starving for gass. im not sure when the accelorator pump kicks in but check to make sure no abstruction it in the brass tube in the track (it will squrt out gas twards the piston) also a new plug couldnt hurt. try punching it in 3rd 3/4 to wot still sputter... check you pet coock and make sure you have ample petrol... if all else fails get BFH and beat the demons out with several hard blows to the clutch cover... whatevers clever:scary:

[hotrodbelair]

same thing happened with mine i needed to replace the side cover gasket on mine and it sat for like a week before i got around to fixing it after i got it fixed it wouldnt get any gas at all so i took the carb off and just tapped on it a little bit then it started pumping gas i probaly should have taken it out and cleaned it but i was in a hurry to get it running again. and before the side cover went i was on the trails and notice it would sputter 2nd and 3rd gear at quarter throttle dont do it any more

[muddy400EX]

this may sound dumb but it happened to me. when it started getting hot outside it did the EXACT same thing your talking about. i tryed changing the jetting, needle and everything. ended up being the outerwear on the kn wasnt letting enough air in, im running a UNI now;)

[44oEX]

play with the needle...it is probably that it wappend to me before

[hotrodbelair]

i rember when i first got it there were holes drilled through the airbox so i sealed them up cause i rode in pretty sloppy conditions and when i sealed it up it ran rich every time i would nail the gas from idle black smoke would come out the exhaust how would i adjust on that i ended up un sealing the airbox cause when i sealed it up it took some top end out of it

[honda400ex2003]

A 170 is way too rich on the top. I would try the DJ 146. that is what mine reccomended in my ionstructions. I am using groove 3 DJ 138 and 3 turns on the screw. I live in Wisconsin. I think it is like 1500'. It runs really good with that. just what my settings are. I also have all of the things you have. A t-4 slip-on, k&n with outerwear, and the same jet kit. Steve

[grant.uirsmo]

my buddy is having the local shop install a new cam and while its in tune the carb and re-jet if needed

thanks for the help