Jetting the bike, how do you know what to buy?

I am in Maryland, Baltimore to be more specific. How do you know what to buy to jet the the bike for the 3x3 mod? I saw in the faq that I need the dynajet because I have an S, but it says "and the appropriate jets for your altitude."

Can someone help me and tell me what to buy please so I do this right? Is there a chart or something somewhere that I haven't found?

Also, if you have to buy the jets seperate, then what comes in the dynajet kit?

Sorry for being so stupid about this, but I've only looked in a bike carb once about 15 years ago and remember very little, other than the fact that we couldn't get the bike working again for the life of us. So I'm hesitant to do this mod.

Thanks guys.



I am by no means an expert but I just did this mod 2 weeks ago. The Dynojet kit provides a new needle, a new spring and a few jets for your carb.. My California E has your carb so I got the S kit. I'm all stock and based on the FAQ for jetting I needed a 140 main jet and a 25 pilot with the 3x3 at sea level. The dynojet kit I bought didn't have either one of those jets so I had to buy them separate at 2.00 each (no biggie). If you go to you can read the PDF files of their kits to see what's inside....

Dependent on what mods you have and what Burned recommends than the new 3111CA Dynojet Kit may have ALL the parts you need for your S. I'm sure someone else will chime in on this. :thumbsup:

check the jetting forum here on TT, look for the jetting database. lots of good info. also use the search function and type in "drz 400 s jetting", "burned's jetting specs" also look for "3x3 mod".

DC is at sea level, B-more should be close to the same.

Maybe we could team up and do the mods together.

140 main and 25 pilot sounds right for sea level. Burned recommended a 138 main and 25 pilot for me at 1500+ ft. I have a Yosh slip-on.

The other variable is needle position. I think 3rd is what's recommended.

If I didn't have a FCR carb I'm about to install and/or was doing the jetting on my Mikuni for the first time, I would be prepared to "play" with it a little. Try a 138 or 140 main and try both 3rd and 4th clip positions on the needle. See which results you like best. I guess the same attitude goes for the FCR.

As I've read in this forum, jetting is an art, not a science.

By the way, I was able to pick up the jets I needed locally. A few phone calls to dealers/repair shops and you may be able to find them too.

Ask burned, he will either check in here or go to the jetting forum and ask. Tell him you elevation, temperature, and any pertinent mods you've done ie 3x3, exhaust etc.

I posted this over on the jetting forum yesterday morning and Burned never replied. I'm ready to buy the dynojet kit today but am not sure if I should purchase other jets with the kit...

B-more is 2m above sea level...




Wow, I had no idea you need to know what jets, I thought the kit came with an array of jets.


I will have an S model with E intake cam, E base gasket, E exhaust, and 3x3 mod. Michigan appears to be at 860 feet, but I go south twice a year and ride in higher elevations (never more than 5k feet) I have not bought a dynojet kit but plan to in the next few days. Recommendations?

the jetting info is all over this forum (at least it was).

The recipe I used after compiling an average based on the mods I had done, was fuel/air mixture screw out 1/4 turn (I think), 142.5 (stock) main jet, 25 pilot (they come in 2 lenths-get the long one), dynojet needle is all you use from the kit (many use the slide spring too). This recipe is for sea level to my altitude of 1500 ft. with 3x3 mod, can also be used with openned end cap (hole saw, drill out the spigot) aqnd hotcam intake and after market airfilters.

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