Do all the 400ex's from 99-2008 have the same stock jets?

[f4iracer]

Hello,

I'm using the 99-2002 owners manual and i just wanna make sure that the stock jets would be the same on these models. i'm gonna check the jets when i pull them out, however i'd like to know what jets i need to pick up so i have them around.

if they are the same i'm gonna get a 150, 152, 158, mains, and then a 40 and a 42 pilot.

lexx slip on
uni air filter lid on

[honda400ex2003]

I believe the jets are the same but the needle is different in the new ones. it is not adjustable anymore. It may be a different size also, i have never really heard a definitive decision on it. What kind of elavation are you at? I ran a 138 DJ with my t-4 and k&n at about 1500 ft. I will look and see what the exact conversion is to keihin. steve

[honda400ex2003]

a 138 is a 150 so anywhere in there considering your elavation. at sea level try a 154 anywhere inbetween. try 3rd clip position (stock) and about 2.5 turns out on the f/a screw if you put in a 40 or a 42 go with 2 and see how it runs. you may have to do a bit of fine tuning with that but it will get you close. steve

[f4iracer]

I'm at 700ft elevation. So do ya think i should put in the 42-152 or the 42-154

I've got all the jets already.

[honda400ex2003]

i would go with a 152, 42, and 2 turns out then check your plug and see how it is. if it is popping on decel then go to about 2.5 turns out on the f/a and see how it does. steve

[f4iracer]

thanks for the quick reply.

my stock a/f screw is 2 1/4 out. I was already thinking i should move that to 2 1/2.

do you think i should go in to just 2 out?

[honda400ex2003]

sure you can try it and see how it runs. if it pops then go out a bit. if not go in some and see how it does. you will be able to tell when it is running best. just make sure it is warmed up first. steve

[f4iracer]

ok sounds good, i think i'll just put the 152 in and not adjust the a/f. If it's popping i'll adjust, otherwise i'll leave it.

Do you think i need to put the pilot in also or should i just try this 152 first.

[honda400ex2003]

i would leave it and see but it is up to you. the pilot does not affect the main so if it starts hard you can put it in. I would prefer to see you do one at a time to note the changes it makes to the system. If you start to change multiple things then it can get confusing really fast. good luck, steve

[f4iracer]

I just put the 152 main in.

I didn't take the carb out so i haven't made any other adjustments however i will say that the quad seemed to warm up faster, normally i gotta work the thorttle for awhile when i'ts cold, this time worked the throttle for about a min. then i put it in reverse and it didn't die!

I didn't notice any power difference that i could tell. It seems to run a little harder i guess but i can't really tell. I'm gonna run it more this week to see that it's tuned correctly..

Thanks for all the help, i may be back for more.

[honda400ex2003]

what you should do is warm it up good, then change the plug in it. then ride it again for 20 minutes and take the plug out and look at it. Ride it at all speeds too just to make sure. If it is brown you are good black too rich white too lean. You should be able to judge it by that pretty good. If you cant really tell on the plug put it back in and ride for a while longer. Steve

[f4iracer]

ok i'll change the plug next time before i go out and then i'll check it after the ride. thanks.

also, do you think i'm ok with the stock 2 1/4 out? (i think that's what it is). I wasn't gonna play with the pilot screw. I guess if i notice any popping i will have to.

Can you get to the pilot screw without taking the carb out?

[honda400ex2003]

leave it for now since you want to make sure it is running good with the new main first. make sure you warm it up on the old plug then put the new one in. also, you can adjust the f/a without taking the carb off, it is kindof a pain but with a small flat head you can get it in there at an angle and turn it. good luck steve

[f4iracer]

ran the quad all weekend. A little backfire while it was warming up, but once it was warm i couldn't get it to backfire if i tried. Not much back cackle on the decel either. I still need to pull the plug to check but i'm pretty sure i have a good setting.

I'm wondering if i should try a bigger main jet? Maybe try to get a bit more power out of it.

[bmid450]

does your Lexx have the quiet core in? if it does a 152 with lid on is plenty,try a 40 pilot it will help with starting.

[f4iracer]

core is out.

[honda400ex2003]

Originally posted by f4iracer
ran the quad all weekend. A little backfire while it was warming up, but once it was warm i couldn't get it to backfire if i tried. Not much back cackle on the decel either. I still need to pull the plug to check but i'm pretty sure i have a good setting.

I'm wondering if i should try a bigger main jet? Maybe try to get a bit more power out of it.

I wouldnt, check the plug first, it sounds like it is running really good right now. Steve

[f4iracer]

I just ordered an EHS lid for my airbox.

I'm sure i'll get some backfiring after i put the lid on.

Do you think i'll need to go to a 155 main?

I'm wondering if i should try to go up to a bigger main the way it is, i'm not getting backfiring but i do get a little back cackle on the way down if i wind it out.

Anyway do you think putting the airbox on will require me to go bigger on the main jet.

[honda400ex2003]

you can give the 155 a try and see how it works. to see if the pop goes away a bit yoiu can turn out the f/a screw alittle bit. Where are you at for jetting right now? Some popping is normal though so i wouldnt worry too much about it. just my .02 though. steve

[f4iracer]

right now all i've got is the 152 main jet. I'm still using stock air filter with lid on and then the lexx slip-on.

I think it' sjettted almost perfect right now but i'm worried that after i put the air filter in it might get lean on me again.

[honda400ex2003]

it most likely will be lean enough to have to put in a bigger jet. steve

[f4iracer]

hey steve when i go to put these jets in, i'm gonna have to shim the needle with a washer, do you know of any how toos or even what size washer i need to get? Basically when i get into the carb i wanna know what i have to do and i wanna have everything on hand.

I wasn't gonna adjust the needle but it sounds like i may have to on this next re-jet.

I've ordered a 40 and a 42 pilot as well as a 155-160 keijhen jets. I'm gonna put the 155 and the 42 in, and probably go about a quarter to a half turn out on the a/f screw. Also, for tuning purposes, can the a/f screw be adjusted while the carb is on the quad?

[honda400ex2003]

honestly i am not sure how thick the spacer is since i dont have one for mine. I have the old needle in mine. I have heard that it is half a notch on the needle so you would need two. i dont have a micrometer to measure my needle or i would just go out and measure the distance divide it by two and that would be the thickness of the the spacers. I would check out the 400 section and see if anyone else knows. Otherwise you should be set with a couple of screwdrivers and some small wrenches to take off the main jets and such. it is a pretty easy change to do all of them. what you may want to do is change only one thing at a time so you can see how each one changes it and if it helped it or made it worse. that way you can get it perfect on each part seperately. steve

[f4iracer]

Thanks man,

Ok, so i think i'll put the air filter in, then run it around and see how my plug looks. It's a 152 main right now so it might be lean after the slip-on and air filter.

If it's lean, i'll change the main jet to a 155 without changing anything else.

Then we will see how it runs......

do you think adjusting the main jet like this will affect my idle and 1/4 throttle? should i go ahead and turn the a/f screw out another quarter to half turn?

I guess what i'm getting at is, if I only adjust the main jet do i still need to adjust the needle and a/f screw?

[honda400ex2003]

the main will have no effect on the lower stuff, so you will have to do the rest also. I would start with getting the pilot right then the needle then the main. you can idle it for a while with a new plug to check the pilot, then do the needle at about 1/2 throttle, and the main at WOT all with new plugs. you can try to turn the f/a out a bit more to see if that helps idle and such too. steve

[f4iracer]

so i can't just throw a 155 keihen in there and let it rip?

i'm sure with my setup a 155 and a 42 will work just fine, it's the needle i'm mostly worried about.

[honda400ex2003]

yeah it should be fine. if you feel it bog at mid throttle then move it up, you could test it too if you want and move it one up and one down to see if it gets better or worse. just leave as much of it apart as possible and take it for a quick ride you will be able to tell if it gets better or not. if it doesnt move it back were it was. you will get it with that setup. steve

[f4iracer]

alrighty that sounds good, thanks for the pointers. Should i bring the a/f screw out a little too? I gotta get that D shaped tool, dammit!

[honda400ex2003]

you may have to but try it without moving it first. that is mainly to fine tune it to final product anyway. steve

[f4iracer]

Alright, i had the 155 in and it was stumbling. I think the 152 is all i can go right now with just the slip-on and air filter.

the pilot is still stock 38. One day i plan to put either a 40 or a 42 in, but it's still starting fine with the choke on.

Do you think the 38 pilot is too lean for my setup or will i be ok leaving that and sticking with the 152.

[honda400ex2003]

it should be ok. mine starts better in the cold with a 38 and the choke than with anything else without the choke. I guess it is up to you a couple of sizes doesnt make a huge difference so you should be ok for now. steve

[f4iracer]

I put the 42 in, and i'm leaving the 152 main.

I've got a uni and a slip-on.

I noticed the quad was kinda slipping when i'd be barely on the throttle so i think it was too lean down there at 1/8th throttle and that's why i put the 42 pilot in.

It definetly starts alot easier now with the 42 pilot.

i'm curious, since you're running stock pilot with all those aftermarket adjustments do you notice that it's kinda lean down at the low accell?

I mean your pilot circuit has to be lean with your setup and a stock pilot.

[honda400ex2003]

i dont really notice much with it popping. i have my f/a at 3 turns out most of the time and it seems to do alright i guess, maybe it will be different with the 450 carb i have now. i will see. then maybe i will experiment with the 400 carb if i get board one day. i will try some different pilots and such with it. mine starts fine in the cold with the 38 so i guess it is ok for now. this is actually why i leave it in. it gets cold here more than some places. at night it is nice to have it start easy instead of pumping and all that. steve

[f4iracer]

i knew mine was lean with the pilot cuz it was surging down at very low throttle. Like if i was barely on the gas it would kinda lunge and then back off.

i'm sure you quad does this too with that stock pilot still in there right?

[honda400ex2003]

i dont really have a problem with mine acting up or i would fix it for sure. it runs good how it is with the 38 in it, also i try to keep the f/a out around 3 to help it out a bit. i will see how it does with the 450 carb here this weekend and see if there is something i have been missing. steve:devil:

[f4iracer]

I'm fouling plugs like a mofo now.

I went out to start my quad this morning and it wouldn't start, just rolled over and barely tried to start. I gave it numerous attempts cuz i thought it was flooded. Well, i changed the plug and it started right up just fine.

My question is...........is the 42 pilot the problem

the quad ran fine with the stock pilot and the 152 main jet. idled fine and everything

Also, when the quad is warmed up, it will begin to idle slower and slower until it dies. I think i've got a rich pilot right?

I bought a 40 pilot when i bought the 42 so maybe i'll just put that in and then see what happens???

Any advice is greatly appreciated!

Forgot to mention, the plug was super black when i got it out.

[honda400ex2003]

i think it sounds a bit rich if it was me i would put in the 40 and go to about 2 turns out on the f/a and see how it does then. do you have a choke still or no? steve

[f4iracer]

yeah, i still have the choke. Everybody says i sure be just fine with this setup, but i'll take it apart and see what's going on tomorrow.

I'm wondering if i should try not to use the choke when i start it. The last couple starts were just real quick to move the quad so it coudl have easily just fouled out.

the main jet is fine it's just the idle that's a little rich i think.

[honda400ex2003]

i would try to turn the f/a screw in about a 1/4 turn and see if it starts up better. steve