Continued: The JD Tech Support dude had me install it. It fits tight and secure and is well thought out for the 450X. It's easy to get at , but tight enough not to vibrate loose.
This fuel screw ROCKS!!!! I ordered the STR fuel screw, but after talking with Ken via email I decided to go with this one. I am very glad I did. When my order arrived I looked at the STR fuel screw I ordered for my riding partner. It is a very good looking piece, but would be a tight fit on my CRF450x. Also the customer service is the best I have ever dealt with. I will be doing all my online business with CRF's ONLY from now on.
When installing this or any fuel screw make sure you install the spring. The spring provides spring pressure on the treads of the fuel screw to prevent the fuel screw from backing out due to harmonic vibrations. Besides the spring there is also an o-ring gasket and washer. All three of these needs to be installed correctly when installing a fuel screw.
Installed screw, set to recommended setting and it hasn't moved at all after some pretty rough riding. Much easier to adjust compared to the stock screw. This one works great.
Regarding the previous review: If the washer, o-ring, and spring are installed and in the correct order the likely culprit is the spring. If you have tightened down the fuel screw all the way it often compresses or collapses the spring as it's a small spring. This eliminates the springs ability to provide the necessary spring tension on the fuel screw. Often you can remove the spring and stretch it back to it's designed length and reinstall with good results.
Much easier to adjust than stock screw. I can now reach in the left side of the bike and turn the fuel screw without having to loosen and rotate the carb. Bike runs great.