atf8611 Posted April 7, 2010 Any tips on how to jet a kx125 for high altitude? I have never really messed with carburators (other than cleaning) and I am not sure what adjustments to make. The bike will be ridden mostly from 6000-8000+ feet. Thanks! Share this post Link to post Share on other sites
The Spanky My Ride Posted April 7, 2010 You will definitely have to jet leaner. I have no experience with altitudes higher than about 3000 feet, so I can't really advise you on how much leaner. Share this post Link to post Share on other sites
atf8611 Posted April 7, 2010 Sorry, I forgot to mention that I knew that I have to drop probably 2 sizes in the main jet. My biggest question is, does anything else need to be adjusted? The bike seems to run fine right now (starts first kick) but I have never ridden a 125 so I have no idea if the engine is performing anywhere near how it should (I have only taken it around the neighborhood so far). Share this post Link to post Share on other sites
BrokenSpoke2 Posted April 7, 2010 Not only will you need to drop the main jet but you will also need to raise the clip on the needle, go to a smaller pilot jet, and back the air screw out. I will take a look in the manual tonight when I get home and see how much of a drop it recommends. Share this post Link to post Share on other sites
WYMX Posted April 7, 2010 I just answered this a couple of days ago... "@ 6000 ft I run 390 main, 32.5 pilot, second clip on a leaner needle and a leaner slide." And two turns out on the air screw. The mikuni specs call for a 370 main(in warm weather), but I'm kinda lazy and don't wanna change jets all the time. Always run 32:1 (or even more oil) and jet from there. Look around for jetting guides on this site and honor those posted by Chokey, he knows of what he speaks. Share this post Link to post Share on other sites
