I have a 2001 400ex with a complete DMC Alien exhaust and a K&N air filter. Having a hard time jetting, just doesn't feel right. Any help would be awesome. Thanks!

 

its hard to keep the same feeling as when it was stock...........

stock, all the power is a the high rpm range.........

now with the pipe and filter your power has probably moved to low end and mid range.
making it feel not quite right at high rpms,,,,,


have you re-jetted at all??????????

 

I have tried pilot-42 and main-152

 

AT FIRST, I HAD THE SAME SET UP. I TRIED 152, 160, 162, 165, 168, 172 MAIN JET. THE 168 MAIN WORKED BEST FOR ME AND IT STILL WORKS BEST WITH MY 440 MOTOR. I RACE MX IN SOUTHERN CALIFORNIA. WHERE YOU LIVE OR RIDE MIGHT PLAY A BIG FACTOR ON THE SIZE OF YOUR JET. DIFFERENT ELEVATIONS, DIFFERENT JETS.

 

I ride a little bit everywhere where I ride up North of Seattle its about 500-800 ft. Then I like to go down to the Oregon coast to the dunes about 4 times a year. Thanks for the responses.

 

Did you move the clip on the needle? If you didn't you need to move it one down(so the needle is coming up sooner). Did you mess with the pilot screw at all? This is my setup 158 main, stock pilot, needle moved one down( I always get the up and down terminology mixed up). But I have no lid on the airbox(big difference). Run yours with no lid and see if it is better, worse, or the same. Better means your to rich. Worse means to lean. Same means ??? Also when I added my DMC I seemed to lose some bottom end. Also try this question on Exriders.com and you will get a ton of responses better than mine.

 

I have not messed with the needle or with the pilot screw, but I will try those. Thanks for the responses fellas.

 

I dont know about your elevation. I am at about sea level. I just put in a 155 main and left everything the same. I have an FMF powercore tho. Most EX pipes are the same so it's worth a shot.

 

Hey crabbybob (havinnoj). Leave your air screw and pilot the same. Just change your main from 155 to 162 or 165 or even 168. See which works best for you. 168 means less bottom more top, 162 means so-so bottom more mid and less top. 155 means you are starving you motor of fuel. I think 162 should work perfect for you.

 

Hey ORANGE400exRACER Im not the one with the question!! Thanks tho. The bike runs fine and just sits but if I run it again I might move the jets up some.