check out this post first:
http://forums.sohc4.net/index.php?topic=34426.0if you're intimidated by the idea of doing a full carb rebuild, don't be. it's really not that bad after the first time around, which you'll want to do very slowly, take photos, arrange parts carefully, etc. but then again there's an easier approach that might just do the trick.
try just removing the carbs from the bike, removing all the jets, floats, gaskets, etc. and then dunking the entire rack in a 50/50 solution of simple green that you can pick up at your nearest walmart/hardware store. let it sit for a few hours and then rinse everything out and blow it dry. clean the jets with some carb cleaner and blow those out with some canned air. if the float needles are sticking or the bowl gaskets are worn out, replace them. you can pick them up for < $30 on ebay. there's a guy that sells po'boy carb rebuild kits that work great for quick jobs like these.
good luck.