I'm kinda surprised that nobody's brought up Ibsen's "Ibby-izeing" method. Take some hot water (I put the kettle on and boil it), some baking soda, and a container that will handle the boiling water, add carbs and voila! CLEAN carbs! I have had some great results with this combo.
Oz
PS: I just re-read this and realized that I was prolly a wee bit vague! 1.) put parts in container. 2.) sprinkle copious amounts of baking soda on parts. 3.) put some HOT tap water in container---fill till parts are 'bout half covered. 4.) when the tea kettle is whistling, sprinkle more baking soda on parts and pour the boiling water into the container 'til the parts are submerged. 5.) let stand for an hour or two, rinse, repeat if necessary.
note: there will still be some schmutz on the carbs that needs to be scraped off ( I used dental picks, steel wool and compressed air ) but the results were great! When I first got my bike, the carb slides wouldn't budge. After a soak in the solution, the slides moved freely.
Good Luck!