Jetting Help

[RaginRedneck]

Any help that anyone could provide would be much appreciated. I just got my shipment of toys in and I'm trying to figure out the jetting. I thought I had a pretty good idea, but the instructions I got with the jet kit are way different than what I was thinking.

Details: '07 400EX, brand new. Moose Racing CDI Box, K&N Air Filter, White Brothers X2 slip-on exhaust. I live at 700ft of elevation, the highest I'll ever ride is 3000, but mainly around the 500-1200ft mark. Temperature range is approx. 40-70(Winter/spring riding - Summer/late Fall Riding)

I was going to start at a 155 main jet and then adjust from there, figuring if I was too rich, no damage to the bike, if I was too lean than it wouldn't be by much and no damage to the bike. However, the JEt kit I got said to use a 142 Main with stock exhaust, and a 146 main with aftermarket exhaust. I believe stock is 138.

Any ideas? Also, do I need to change out the slow jet?

Thanks to all for any help that you can provide, I recently became a member, but I've been searching this site for ideas since I bought my 400EX(my first quad) in January.

[RaginRedneck]

I will reply to my own post in order to possibly help out others.

Mistake #1: After realizing I was running extremely on the rich side I did some more research. It took an hour of cruising this site, but I realized that DynoJet numbers their jets different, so when I put in the DJ155 Main Jet, it was really equivalent to a 170. I found a great article (I believe it was under the how-to section) that listed a cross reference for the jets and realized I needed the DJ146(as suggested) which was equivalent to a 155.

After installation of that and the 40 main jet, the bike runs great. I had to play with the mixture screw a little bit but at 2 turns out I seem to have gotten the nice tan look that everyone wants.

Note: A little trick that helped me, to get to the mixture screw which on my '07 is on the bottom of the carb. Loosen the hose clamps and rotate the carb to the side in order to get at it a little easier.

Hopefully this helps someone else.

[bearair]

Just put a dynojet kit in mine last night. Dynojet recommends the 170 jet (stage 2) for a slip on, no airbox lid, aftermarket filter and elevation below 5000. 165 at higher elevation. They recommend much smaller jetting for the airbox lid being on. The mixture needle is run in the #3 position with the the stage 2 and the #4 with the stage one.

I'm putting the Curtis Sparks 6 degree key in right now along with his air filter kit. I'm going to run the 165 with the airbox lid off and see where that gets me. It seemed to run a bit better last night before I took the case off tonight to get at the flywheel.

After that I guess I'll read the plug and see what happens. Good luck with yours!

[bearair]

Okay, I like so many others evidently have discovered that Dynojet is barking up a tree with their jet recommendations. 165 is too rich. I'm bumping it down to a 146 tonight which looks like it will be a much better fit. I'll run it and see what I think.