A lot of guys running Edelbrock carbs have a problem with a high idle. One cause of this is the return spring being too weak.
This modification is inexpensive, and takes about five minutes to install.
I bought a "Bag Of 101 Springs" at a local hobby shop for a couple of bucks. After finding the correct size, I attached one end to the accelerator pump linkage and the other end was zipped tied to the frame. I glued a small piece of mousepad under the frame to prevent the spring from moving around. The accelerator pump linkage does not rotate, so wear to the spring or linkage should not be a problem.
After installing this spring, my carb now "snaps" shut when letting off the gas.
This mod was done on a Honda XR650R, but with minor tweaking will probably work on other models.
Special thanks to Dafna for her help taking and posting photo's.