Hi everyone,

I just put a DMC Alien exhaust on my 400ex yesterday. I also have a K&n air filter with no airbox lid. I followed the suggestions on DMC's website for jetting and put in a 155 main jet and a 42 pilot jet. I could not however, find out how to change the clip position on the carbeurator. They recommend running in the fourth clip position. Now the quad idles funny. It will idle for a few seconds and then will "cough" and sputter. Then it will idle for a few more seconds and "cough" again. It also backfires on decelleration when I rev it up. Is this because I didn't adjust the clip position? Could someone tell me where the clip is to adjust it, because I'm not really familiar with the style of carb on the 400ex's. Or, do you think that's even the problem. Could it be the air screw? Where is that located on the carb? Any help with this would be HUGELY appreciated!
Thanks in advance for any help with this!

 

To get more responses go to exriders.com. You can go there and use "search" and they have a ton of information or just ask this question again. Have you tried adjusting the idle? Was the bike %100 stock before these mods? Did you put new exhaust gaskets in with the exhaust? I would definetly change the clip position. On top of the carb is a gold plate with three screws in it. Take the screws out. You have to be careful with all the screws on the carb because they are tight and made of soft metal. Make sure you don't strip them. The right size philips and alot of pressure on the screw helps. I used a philips that is an L shape( I don't know what they call them), they put alot of torque on the screw. After the plate is off, there are two more screws(really hard to get to and to get off). Do all this with the carb off the bike.

 

Thanks alot for the reply.

Yes, the bike was stock before I did the exhaust and jetting. Adjusting the idle didnt seem to do much. I didn't put in new gaskets as I bought the pipe used and it didn't come with any. You think this might be the problem? I'll try adjusting the clip position and see what happens. Thanks for the help! Anyone else out there with any info, PLEASE post a reply!

thanks

 

The exhaust gaskets won't cause it to idle bad, but it will cause a popping under deceleration. Adjusting the clip position isn't going to fix the poor idle either. The idle probably has something to do with the 42 pilot jet. I would mess with the pilot screw. I would adjust that and see if your idle clears up. It's very hard to get to. It's on the bottom of the carb.

 

I'll try that. Thanks alot for the help. I also checked out exriders.com. AWESOME! I'm waititg to be approved and will post this question there as soon as I am. Thanks for the tip!

Keep the info coming!

thanks

 

jetting Try here.

 

Thanks Dariusld!!!!!!!!

I took the carb back apart and adjusted the needle clip position, tightened down the header pipes some more, and tightened up the carb boots and now she runs SWEET!!!!!

No more backfiring or "coughing". My EX has TONS of power now compared to stock!


Thanks for the replies in this matter, they were alot of help!