FAQ: Where is the Idle Mixture Screw?

No replies to this topic
  • grayracer513

Posted September 28, 2008 - 07:47 AM


The idle mixture screw, or pilot screw, on an FCR carburetor controls an emulsion of fuel and air. That means that turning the screw out makes the mixture richer, and in makes it leaner, the reverse of common practice on two stroke and older four stroke carbs, but the same as on most automotive carbs. The screw is located under the carb, up inside a well in the float bowl, just forward of the jet access plug:


Here, with an extended screw in place, is where it is, viewed from the side:


The large, bright metal screw just below the fuel line is the idle speed adjustment screw. In is faster, out, slower.  On YZ426 and earlier models, the idle speed knob is black plastic.

Additional info on adjusting the pilot screw:



Related Content


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.