I want to know what i should jet my 2003 kx 125 to. I have never had a good looking plug come out of it. It always is a very dark chocolate or has carbon on the insulator. I am using a b8es plug and the jetting is 420 main, 40 pilot, needle 1st position, air screw 2.5-3 turns out. The altitude is around 1000-1500, 70-90 degrees, and humid(i live in missouri). The bike seems to load up quick. I was thinking of going to a 37.5 pilot, needle 2nd position and a 410 main. I am a novice rider and am pretty slow at the track. Even when i ride in a field the plug does not look great. When i went to the track last time, i used a 7 plug and it even came out on the dark side. I am very scared of siezing my engine or running it too lean and causing damage. I run yamalube 2R at 40:1 with 91 octane pump gas. would it be safe for me to change the jetting to what i listed above. If not, then please reccomend jetting that i could change to and reassure me that i will not sieze my engine.
Jetting- please read this Mr. Gorr
- Thread starter kawakx125
- Start date
Eric doesn't currently have an internet connection so he won't see this anytime soon. Best bet is to learn how to jet on your own, and here's a great starting point :
http://www.ericgorr.com/techarticles/carbtuning.html
http://justkdx.dirtrider.net/printcarbtuning.html
http://www.ericgorr.com/techarticles/carbtuning.html
http://justkdx.dirtrider.net/printcarbtuning.html
- Jan 25, 2000
- 1,822
- 0
The '03 KX125 is a real spooge factory with the stock jetting (as most 125's are). Most people are running a 37.5 pilot jet, but I've even gone down to a 35.0. I'm not sure where you're going with the needle clip because the first position (top) is the leanest. Stock is the 3rd position, but most put the clip in the 2nd (from the top) position, which is a bit leaner than the stock setting.
You can try different main jets, but the pilot and needle clip are the things that should be changed first. Keep in mind, however, that your KX may not be exactly the same as the next persons. Also, the '03 KX125 is not the easiest bike to jet clean, but it's not impossible and not the worst (well, at least not really bad).
You can try different main jets, but the pilot and needle clip are the things that should be changed first. Keep in mind, however, that your KX may not be exactly the same as the next persons. Also, the '03 KX125 is not the easiest bike to jet clean, but it's not impossible and not the worst (well, at least not really bad).
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- Thread starter
- #5
I have already moved the needle into the second position. I am going to change the pilot to a 37.5 Thursday provided the jets are available at the shop. After i ride with that for a little while, i am going to put in a 410 main. Is there any way to tell if the main jet is correct without doing a plug chop? I dont know of anywhere around here where i could do one. I will just ride the bike as i normally do and if the plug looks good and the main jet ring is right, i will be happy. The only place i could do a plug chop at is up my neighborhood street, which is maybe 1/4 mile. Would that work.
