set up idea for new trx400ex

[eliasxr400]

I just bought a new left over 05' 400ex. It is totally stock. I want to mod it a little. I have a xr400 and am familiar with the motor, but want to wait on engine mods. I also do not feel the need to mess with the tires or suspension just yet. I want to wear down the stock tires first and I like the small wheel base for trail ridding. I just want it to breath a little better.

I was thinking of this set up; UNI air box cover, K&N filter, polished HMF sport series slip-on, and Moose jet kit. Total cost $365.

If I do go with this set up, what jets should i need at sea level?

[400eXr1d3rZ]

155 main 42 pilot and 2.5 turns out the air/fuel screw, needle on 3rd notch from top.

Do you ride in wet muddy terrain? Foam filters work better in those conditions.

[eliasxr400]

Thanks for the info.
I do ride in wet conditions but not very often. I've had very good luck with K&N filters in my dirt bikes.

[mitchamus]

remove the choke.

[400eXr1d3rZ]

Originally posted by mitchamus
remove the choke.

Thats a good mod too, as soon as you put the 42 pilot in you won't ever use the choke again anyway.

[eliasxr400]

Originally posted by mitchamus
remove the choke.
What is the theory behind this, more air flow?

[underpowered]

Originally posted by 400eXr1d3rZ
155 main 42 pilot and 2.5 turns out the air/fuel screw, needle on 3rd notch from top.

Do you ride in wet muddy terrain? Foam filters work better in those conditions.

that jetting is only a starting point, you will have to fine tune from there. i would start a little richer, but thats just me. i ran a 165 in a 400 with a similar setup except it had a pro circuit slip on, but every bike is alittle different.

and actually a K&N is better in wet and muddy terrain. the K&N is not made for dusty, where a foam filter shines.

[mitchamus]

here is the link the remove the choke.

http://www.atvriders.com/articles/choke400ex.html

[Wheelie]

40 pilot and 155-158 main.

Remove the choke.

[flauge]

Originally posted by eliasxr400
What is the theory behind this, more air flow? Yea, it helps the carb flow a lil better. I noticed a pretty good difference in throttle response when i did it.
Also, i know you said you didnt want to do anything to the susp. But im still gonna suggest the gt thunder rear link & maybe shock revalve. You'll be glad you did it., the rear will ride a whole lot smoother and soak up bumps better.:cool:

[AZ_TRX400EX]

How do you know what size pilot jet you have? I know I have a 165 Main. Also when adjusting TURNS do you count 360 degree revolution or from one oint of the screw driver to another?

[Eviltanker]

Get a jet kit cuz you can't move any notches since your needle is fixed on 05' through 07' . I'm going 150 and 42 cuz, a 152 was actually to rich on top. my engine mods are K&N filter ,airbox lid off with an outerwears cover and an HMF slipon.

[flauge]

Originally posted by AZ_TRX400EX
How do you know what size pilot jet you have? I know I have a 165 Main. Also when adjusting TURNS do you count 360 degree revolution or from one oint of the screw driver to another? If your not sure what size it is, then i think the only way to find out is to take it out and look at it. If its stock then it should be a #38, i think.
Youre right on the turning, it'll be one full rotation of the screw, or 360 deg.:cool:

[eliasxr400]

Originally posted by Eviltanker
Get a jet kit cuz you can't move any notches since your needle is fixed on 05' through 07' . I'm going 150 and 42 cuz, a 152 was actually to rich on top. my engine mods are K&N filter ,airbox lid off with an outerwears cover and an HMF slipon.

Eviltanker, do you like that setup?
How much do you think you gained?
I am going to order the same set up this weekend, is it all worth almost $400?

[Eviltanker]

yeah buddy! My 400 is sick now, it hits the rev limiter so easy.We actually went with a 148 instead of a 150,I'm also putting a Boyesen accelerater pump on. Not sure how much Hp I gained but, you can feel a huge difference.

[krt400ex]

do not get a jet kit. it is a pain in the *** to adjust the jetting and stuff cuz everything is guess work. get OEM jets. i would start with a 152 or 155 main, 42pilot, mess with the fuel screw, and get an adjustable needle and go 2nd or 3rd position. that will get u very close.

i will tell u that i have not had a problem with the k&n filter until today when i cleaned it. there was dirt in my intake and my filter never falls off and it is still like new. i have owned it for about 2 mon. i love the extra air, but next filter i get will be a uni or twin air. i clean my filter alot too. like evry ride or 2.

[eliasxr400]

I just ordered a HMF sport series slip on, K&N Filter & pre-charger, Moose jet kit, and uni air box vents. The total was $346 from a local shop here in Jersey.
He said to remove the snorkel and vent the lid rather than use an outerwear box cover because the velcro seems to come off after a few rides. I am going to get a K&N power lid eventualy.

Also, do jet kits come with pilot jets?

[flauge]

Originally posted by eliasxr400
I just ordered a HMF sport series slip on, K&N Filter & pre-charger, Moose jet kit, and uni air box vents. The total was $346 from a local shop here in Jersey.
He said to remove the snorkel and vent the lid rather than use an outerwear box cover because the velcro seems to come off after a few rides. I am going to get a K&N power lid eventualy.

Also, do jet kits come with pilot jets? You can always get an EHS racing lid instead of that sorry velcro outerwear. Its a good bit cheaper than that k&n lid too..
click here > www.ehsracing.com
I use this with a uni filter and i think its a real good setup. The lid still breathes good and keeps the water out, and the uni keeps the fine dust out.My intake never has any dirt in it.:)

[eliasxr400]

Originally posted by flauge
[B]You can always get an EHS racing lid instead of that sorry velcro outerwear. Its a good bit cheaper than that k&n lid too..
click here > www.ehsracing.com


That looks like a good set up. I may try the kit for $55 before I get a K&N powerlid. Thanks for the info.