new to the 400ex

[underpsi]

I just bought a 99 400ex w/ the yosh exhaust, k&n filter, and was told it was jetted. Runs great and very strong but just wondering what else i could do performance wise without doing a big bore kit? Thanks in advance

[fishnfergie]

Cam, Key, Suspension is always good.

Search is good also.

[underpsi]

i have been searching.. would just the hotcam stg1 be fine as I hear the stg2 is for a 440 big bore? also what key would you go w/ as I hear there are different ones. and then what about the white bros rev box?
thanks

[tri5ron]

for a basically stock 400ex like yours, (with your better airflow due to exhaust and intake), get the Sparks +6 key first.

if that dosent satisfy you, then add the stage 1 cam, and/or a 450r carb, and rejet it again.

forget the revbox all together.
They are a waste of cash on a 400ex.
Save that money, and invest in some better front shocks, and a steering stabilizer. You'll be way ahead of the game.

[underpsi]

now w/ the sparks key do i have to rejet the carb as i am not sure new guy:confused:

[slightlybent47]

The carb upgrade won’t help much if any without a port & polish and a cam.
It won’t do any good getting more air in if you can’t get it out.
The type of cam refers more to the rpm’s then anything.
Stage 1 for low end, stage 2 for mid range and stage 3 for high rpm’s
The sparks key will have to go if you bore it out.
If I was you I would do the suspension first, you have way more motor then you do suspension. It won’t do you any good to go faster if you can’t stay on it.

Hope that helps.

[underpsi]

yea the suspension is next. so i could do a stg2 hotcam and that would work? also w/ the cam swap do i need to do anything else?

[tri5ron]

Originally posted by underpsi
now w/ the sparks key do i have to rejet the carb as i am not sure new guy:confused: The key will not cause you to need to re-jet.

here's some good reading, that will answer many of the questions you will have reguarding performance upgrades for a 400EX.
Enjoy, and welcome to the forum...

http://www.exriders.com/vbb/showthread.php?s=&threadid=410964

[honda400ex2003]

Originally posted by slightlybent47
The carb upgrade won’t help much if any without a port & polish and a cam.
It won’t do any good getting more air in if you can’t get it out.
The type of cam refers more to the rpm’s then anything.
Stage 1 for low end, stage 2 for mid range and stage 3 for high rpm’s
The sparks key will have to go if you bore it out.
If I was you I would do the suspension first, you have way more motor then you do suspension. It won’t do you any good to go faster if you can’t stay on it.

Hope that helps.
unfortunately there is about 2 horse to be had on a stock motor. you should check out the dyno charts at the top that ron posted. he had a few things done but no boring or a cam i dont think. i would not recommend a stage 3 cam for a stock compression motor. it lowers the dynamic compression quite a bit since it is such a big duration cam recommended for big bores and strokers. otherwise the suspension is good, the key would be next and see how you like it then. after this i would look into a stage 1 cam, i think that would be the best overall improvement on a stock compression motor. just my .02 though, steve

[slightlybent47]

I prefer to do all the motor mods at one time. If you do them one at a time yes you do get a small gain each time but there generally small gains and it’s hard to feel the deference. But if you do all of them at the same time you feel a big deference right away.
A lot of people go with a mild build so the reliability is there yet you have decent performance.

[bigbad400]

i would personally go with a stg 2 cam, i had the stg 1 in my first motor and it was good but then i got the stg2 and its really nice. stock bore or not stg 2 is were the powers at. on the stg 1 all i notices was first gear. i usually start out in second when power matters (drag race) so i never felt it. boy the stg 2 thow the second you hit the gear you feel it pulling. you feel the power comming on stronger.

[underpsi]

so is there anything i have to do along w/ installing a cam?