re-jet 02 400ex (first timer)

[fireftr]

Hi and thanks for helping. I am new to the 4 wheel industry and recently came off an 00 YZ 250. I am getting use to a four stroke and recently purchased a white brother e-series, K&N power kit, equipped with filter and dynojet kit. ( Multiples of five up to 170) I've been told my stock jetting is 148. The dynojet co. suggests a 2-4 increase in the main. Now my Question is this. With just these mods. does this mean running a 160 to 170 main (by 5's) or a 2 to 4 up from 148 which would be 150 -152. I have heard from others to go with 158. I've heard with my kit, to go up to 160-165, Since kits vary. I know it's all feel and perfomance but a good starting point would be nice. Also by quick glance it appears I'm going to have to move the gas tank to remove the top of the carb to get to the needle jet. Is this true and is it a pain! Thanks for all the help!

[honda 400ex 69]

ya u have to move the tank its not very hard to get to.

do a search on how to re-jet it gives u step by step instructions

and if i were u i would start at like 155 thats what i have in and it seems pretty good i started with a 165 like it said and it was like skipping when i gunned it

[trailburner]

As far as the jetting I am runing basically the same mod's as you[12 discs in pipe] jet kit,K&N [lid off] I run a 165 main in winter & 160 main in summer, plugs looks great & motor runs very strong!!! does'nt miss at all.......good luck...

[matt400ex]

Do yourself a favor and replace the pilot jet with a #42 while you are at it. My EX was running horrible if at all in the cold weather, and after changing to the 42 it starts fine and idles good. Good luck!

[tryken]

fireftr said he had a dynojet kit. If I am not mistaken the dynojet numbers are different than regular jet numbers, right. I have a k&n and dynojet kit and my instructions say to use a dj146 if using aftermarket exhaust and below 3000ft. I did this Saturday and it only took about thirty minutes from start to finish.

Does anyone know how a dj146 compares to a 155(regular jet). I hear a lot of you saying that(155) is the size you are running.

[Newbie400ex]

Yep, the Dynojet numbers are different. I'm guessing about 10-15 higher than the keihn (sp) jets. I'm near sea level and run a DJ165 @ 50-70 degree weather. I'm assuming you have a 400.

[tryken]

Yes I do have a 400. How does yours run with a dj165. I have the same mods as you do as best I can tell by reading your sig.

[fireftr]

Most of my riding is in the summer and in Michigan. I do beileve at no point are we above 3000(sea level) and lowest is like 200 something. Anyhow I think I'll try the 160 dyno. I don't believe the kit comes with a pilot jet. Many of you say to replace it when doing the main. Now if I use the dyno does a 42 pilot still apply. Also, it comes with a needle jet and does say to replace it. Would this all be easier if I just bout another style main and went with 155-158 and 42 pilot? I'm getting some input and appreciate it, but still could use some reassuring! Thanks!

[toby400ex]

my kit says to run a 146 with my pipe and filter at my elevation

[fireftr]

My kit came in multiples of five, so I don't believe I have a 146. Also my kit suggested to go up in size 2 to 4. If stock is 148, wouldn't that be going down. I kind of confused with all this stuff and really could use some more help! THANKS for the input, it's nice to get some reponses!

[Mr_Bub400ex]

if u want to know HOw to do it i think theres something in FAQ

[fireftr]

What's it under?

[Newbie400ex]

I've used all the way from the DJ146 to the DJ170. The DJ170 worked great in sub 40 degree weather. Then it warmed up and it was running a little rich. I put the DJ165 in and it still might be a tiny bit rich. If I were you I would try the DJ165. It really gave me some good power with the mods I already had on. (pipe,airbox,etc). If you are under 3000ft elevation go with the DJ165 (modded or no airbox lid) You will definately feel the difference. My kit came with 134,138,142,146,155,160,165, and 170. Plus it only takes about 5 minutes to change jets so you should just start high and try 'em till you find one that stands out. I think the instructions that came with these things are wacky:confused:

[Phat2000400]

Just out of curiosity, when you guys say modified air box, are you just meaning you removed the lid or is there some other trick. Also I'm thinking about buying a new exhaust for the Ex and was wanting some opinions on who likes what. Thanks Guys

[fireftr]

That helps a lot! I think the directions are a bit goofy too.Hey did you change your pilot jet? If so what size? To be honest with you guys I"m not quite sure about the smaller jets in the dyno kit I just saw 155 to 170 so I assumed the rest were in mult. of five as well. I'm sure my kits the same.

[Mr_Bub400ex]

i think this shows how to rejet it all
http://exriders.com/vbb/showthread.php?s=&threadid=19832

[fireftr]

I've read that dyno jet doesn't give you a pilot jet and advises you to adjust the pilot screw. So do I change it and go with the a 42 pilot jet or just alter the the screw? I've heard running a 42 will help big time in performance.

[fireftr]

You guys have been huge help!

[sly400ex]

Definately bump up the pilot jet to a 42. I think running a 165 mj will be a good starting point for you. Read the plug after you ride it for a while and then start working from there. You may be a little rich with a 165, or maybe not, but it is still safer to be richer than lean. Welcome to the boards, and stick around for some great info!;)