If you have a Keihin FCR carb on your bike you already know it is a "royal pain in the butt" to adjust the fuel screw on your carburetor. This is because the fuel screw is recessed 1 1/2". Here is little tool that will make adjustments very easy.
First you need to goto Auto Zone (or any auto parts store) and get a 3/16 tube. The one I used was a steel brake line (it doesnt matter what type of tube it is, just as long as its 3/16" in diameter). Then you have to drill out the inside of the tube about 3/4" in with a 5/32 drill bit (this is so that the fuel screw can be forced into the tube (it will be a snug fit...but this is what you want, because you dont want it to come off during riding!) Pictured below you can see the 3/16" diameter steel rod placed over the fuel screw (as you can see from the pic the rod is 2 1/4" long). I also used blue loctite just to make sure it doesnt come off!
Now you need to wait for the loctite to cure (if you used it)! Then you must make a handle so that it will take only seconds to adjust your fuel screw! Here is how I made a handle (you can make it however you want just as long as it works)! I just simply bent over the tubing about 1/3" then I threaded a bolt in (to give more leverage) This is how it looks:
You now have yourself a "adjust on the fly" fuel screw...now screw the fuel screw back in and go ride! Here is what mine looks like after it was completed (doesnt look too bad for under $2 does it?)