They dont make one for a trx250x. And they mostlikely never will. The trx250x isnt a quad that really ever gets modified. So very few aftermarket companys make parts. This is generally a beginner quad used to teach people how to ride. But retro's suggestion of making your own is a solid idea. The problem i see with it is the factory screw is brass(very weak) and the aftermarket ones sold are billet aluminum(very very strong). The brass screw will mostlikely break. You can on the other hand get a pre-05 250ex carb rebuild kit and that will have a flat tip adjustable needle. 05 and after they put the D shaped one in to make it harder to adjust it. My .02