little help with the fuel screw

6 replies to this topic
  • robapril1900

Posted November 08, 2011 - 04:30 PM


was looking at buying this from the parts stor for my new to me 04 wr450. there was a caption that said this at the bottom how do i tell what one i need?
If the Fuel Mixture Screw collar is above the main jet access bolt, it takes an FMS01. If the collar is level with the main jet access bolt, then your carb takes an FMS02

Not sure what they mean by collar.
I know im still a rookie wrencher

  • William1

Posted November 09, 2011 - 06:46 AM


Edited for correctness (Sorry):

You want an FMS01 - Be sure it is Stainless (like from Kientech) or Brass, Avoid the alloy ones.

Edited by William1, November 09, 2011 - 10:44 AM.

  • zlathim

Posted November 09, 2011 - 09:51 AM


I just ordered the FMS01 for my 2001 Wr 426, based on this:

Fits Keihin Pumper Carburetors ('FCRMX'). This part fits all YZ/WR 426F, 250F and 450F bikes, as well as the YFZ quads. It does not fit the YZ and WR 400Fs (uses FMS02). FMS01s fit all CRF450 and CRF250 Hondas, but, they do not fit the 450cc based Honda quads. They fit the new Kawasaki KX250F, and its yellow sibling, the Suzuki RM-Z 250. They fit 03 and newer KTM 'RFS' 4-strokes -450 and 525. It will not fit 02 and older KTM 400 and 520 bikes (uses FMS02).

Please tell me I didn't order the wrong one...

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  • William1

Posted November 09, 2011 - 10:43 AM


No, you ordered right, I was backward in my above comment (I am editing so it will not be incorrect for thext reader). The FMS01 is for all late model bikes. The FMS02 is for the older style FCR.

However... it is an alloy screw and not one that I'd reccomend. This is a short list of good ones:
Merge Racing
James Dean

All have brass or stainless ends.

  • zlathim

Posted November 09, 2011 - 11:07 AM


Thanks for the information. I'll take a look at some of the ones you recommend.

  • zlathim

Posted November 10, 2011 - 09:45 AM


I'm an idiot. My bike already has a brass fuel screw installed. It is the "T handle" one.

Posted Image

I've been wanting to mess with the jetting, so I decided to order up a JD kit. I have read on here that I needed a fuel screw too, so I ordered that Zip Ty unit.

After looking my bike over a little last evening, I realized that my bike already has an extended fuel screw. I am going to really be pissed if I find out that it already has the JD jet set up too.

Sometimes I amaze myself with how stupid I can be.

Edited by zlathim, November 10, 2011 - 11:38 AM.

  • William1

Posted November 10, 2011 - 03:36 PM


Easy to tell if a kit was done. Pull the needle. If the top is painted red or blue, it is a kit needle. However, if you do not have the other needle, it makes wide temp/air density changes a problem. So getting the kit (and not misplacing the parts) is a good thing.


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