400ex jetting question!

[trx400exrider14]

Ok,so i have a slip on FMF powercore 4,and i have a uni air filter.can i run a 150 main and 42 pilot?

[2006 400ex slsd]

i would keep stock pilot and go up on main 2 sizes

[DragonGunner]

It also depends on your elevation, temperture...I always thought the 400EX was a little on the lean side in jetting. I have gone 2 sizes up on the pilot on stock an built motors, seems to start better in the cold. In the stock one with pipe open airbox, k/n filter I run 165 main jet...in cold weather I throw the lid with 8, 1" holes on an it riches it up without the need to change the jetting....the race engine sports a 180 main jet. I always suggest being a little richer is better than a little lean...just keep an eye on your spark plug an how its running....light tannish to brown is A+.

[trx400exrider14]

its not stock,i bought it from a dealership and they never told me anything bout jetting,but i found other stuff they didnt tell me about,and it seems to back fire a bit when i let off the gas,i thought maybe the guy who owned it before put the pipe on and didnt jet it,thats why i was wondering if i could put them on,cuz i was just gonna jet it myself

[honda400ex2003]

i would keep the 150, 3rd notch on the needle, 42 pilot, and go around 2.5-3 turns out on the f/a screw to help with the popping on decel. that should get you dialed in nicely. go 2.5 first and if it still pops go out another half a turn to 3. steve

[honda400ex2003]

also stock turns out is 2.25 so you would go out .25 first and see how it does. then go to 3 from lightly seated if it keeps doing it. you should be able to just turn the carb in the boots and do it with it on the machine. steve

[2001400exrida]

put a 40 pilot with a 152 main in that thing and it'll run like a top!

tr 3 out on the pilot screw unless you're already rich on the idle.

My problem was that when i put a 42 pilot in, i was too rich and had to have the a/f screw at like 2 turns, well my main jet needed it to be at 3 turns so i just put the 40 in and it starts up good in the cold and also runs great without backfire.

[honda400ex2003]

seeing as though it is popping on decel he is not rich...

why spend another 10 bucks on another pilot when he can dial in what he has just fine with the proper procedure. you can run a 48 if you wanted just get it dialed properly and you are fine. no need to buy more than necessary.

unless he is at sea level there is no need to run a 152 unless it is super cold outside when he is riding. im talking below 20 degrees. then in the summer you will need to have a 150 and you will be set.


your f/a wont make enough difference to tell on anything but the pilot. if it does you have other issues. it is not for tuning a main jet or the needle.

steve

[2001400exrida]

take what i said in the order that i wrote it.

"put a 40 pilot with a 152 main"

"try 3 out on the plot"

meaning, after you put the 40 and the 152 main in.

then if you're already rich at this point you would need to go back in a few on the a/f screw.

i meant if you're rich once you put these jets in, because....like i said everybody suggests that 42 pilot but when i put it in my quad with a slip on and an air filter it was flooding at idle. which means it was rich on idle with that 42. I have the 152 main dialed in though. now i'm running a 40 pilot with a 152 main 3rd clip and it runs perfect.

so that's my personal story.

a 48 pilot would run like garbage.

[honda400ex2003]

gotta see a bit of sarcasm dude...

i have ran a 48 in my with no problem if it is tuned right. I ran it with the choke out of my carb and the f/a at around 1 turn out. just gotta get it dialed correctly.

do as you wish. a 152 will be fine for the summer or winter. one size isnt going to matter at all...


steve

[honda400ex2003]

a bit of fun tuning excitement for any pilot jet.

http://s759.photobucket.com/albums/xx239/rocky_mtn_honda/TRX400EX%20Manual%20Pages/?action=view&current=carbadjustment.jpg


steve

[trx400exrider14]

what is the stock jetting on a 01 400ex?

[honda400ex2003]

148 main, 3rd needle slot, 38 pilot 2.25 turns out on the f/a screw. steve

[honda400ex2003]

also you never said that anything was wrong, what your elevation is, or what temps you are running at. that has a big impact on how it runs too. i run at 1500 ft, from temps anywhere from 0 F to 80F with the jetting i recommended. no issues. others lower would need a 152-155 or even more depending on how cold or how hot. the hotter you go the less gas you need. the colder the richer you have to go. if you are running super cold you will want a 155 or 158 at sea level if you are running below zero. it really depends on the setup. a 150 or 152 as we recommended will be fine for any conditions depending on where you are at.


the popping on decel was the only thing stated and requires more gas for the pilot circuit to get that straightened out.

steve