Mikuni TMX needle jet question

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12/12/2018 5:35 PM

Was hoping someone could help me with a question. 2017 KTM 150XCW Mikuni tmx 38 carb, is the needle jet removable and if so what is the best way to remove it. I have purchased an S-4 needle jet and can not get the old one out. Got me wondering if it is in fact removable. Thanks in advance. Doug


12/12/2018 6:20 PM

Its just pressed in there, just remove the main jet and press down on it through where the slide sits.

Check here:


21.5 350 XC-F
96' XR600r

12/12/2018 7:28 PM

Thanks for that, I got it out, was just stuck in there.


12/12/2018 8:51 PM

How is s4 different?


12/13/2018 6:11 AM

garagedog wrote:

How is s4 different?

The s4 flows more fuel down low vs. the stock s1.

Dirthead, are you cutting the slide to a 5.5 to go with the s4? Jetting issue? Try this


2018 KTM 250sx
Instagram CamaroAJ

12/13/2018 9:17 AM
Edited Date/Time: 12/13/2018 9:17 AM

To be perfectly honest, I saw a post on here from LanghamMx that referred to Factory KTM's jetting specs for the 150. So I thought I would try it.

30 pilot
470 Main jet
S-4 needle jet
42-71 needle 3rd clip
2-2.5 air screw

The bike currently has a Lectron on it, and runs good. Its Winter here in Southern Illinois and I'm just tinkering. But thanks for that link.