How do you jet a 400ex?

[raptor88]

I put a HMF exhaust on my wifes 05' 400ex and i put the jet it came with andit runs fine on the bottom and mid end but on the top end it cuts out and sputter. So i went to adjust the needle but hte needle isnt adjustable? so how do i adjust the top end?

[Sparky_20]

first off, is the lid on or off? What size main jet did you put in? What other mods does it have? and last but not least whats your climate and elevation

[raptor88]

lids on, 155p, HMF slip on only, and 6300ft. im just wondering how you adjust the top end, ive done alot of jetting on 450's and stuff but ive never done a 400ex. so this is new for me.

[250x_kyle]

pull the needle out and if the e clip is on the third mark move it to the second. if not does it sputter or pop on decel?

[raptor88]

the 05's dotn have an adjustable needle, thats the problem im haveing, i just dont know how to adjust hte top end with adjusting then needle??

[250x_kyle]

well. if you have rode it did u notice any pop or spuddering on excell or decel? did u try to adjust the air fule mixture screw. i know u have to have a special tool for 05. if you dont let me know i have the tool to do it i got with my jet kit i could hook probably give it to you if you need it. as far as needles go to the dealer and ask for a dyna jet needle for a 400ex. they are completely adjustable and coem with a new eclip and washer. i have an extra needle but i was planning on keeping it for myself

[CarGuy7a]

if the jet you put in is a dynojet jet, then you need to get a dynojet adjustable needle.

if the jet you put in is a Keihin jet. then you need to get a stock needle for a 2004 400EX and it'll fit right in.

a dynojet jet is round with a slot in the top for a flat blade screw driver.

a keihin jet looks like the stock jet with a hex shape.

[CarGuy7a]

the reason for the 2 different types of needles is because the jets flow fuel differently and the needles are tapered differently to meter the fuel correctly for the jet brand.

easiest way i remember what needle goes for what jet is:

Keihin jet : stock needle

dynojet jet : dynojet needle.