George is right; not many (if any) good compounds available anymore on the retail market to clean out gum and varnish on carbs. The good carburetor cleaners and soaks of yesteryear were abolished a long time ago.
That said Tim, if you want to clean varnish and gummed gasoline residue out of a carburetor, I have used plain boiling white vinegar and water to soak my parts and it worked extremely well. Mix white vinegar and water 3:1 and boil the solution in an old pot and get it to boil at a low simmer. Then add your parts and leave them in "soup" for about 15-20 minutes. NOTE: This solution will definitely distort any rubber and/or neoprene gaskets and O-rings you forgot to take off. So make doubly sure you're putting only metal parts in the soup.
Also, I usually do this outside because of the vapors -- that high a concentration of vinegar will make your kitchen and house smell awful.