I have used
this stuff quite a bit in the past. Works well, but you absolutely have to make sure you don't leave any plastic or o-rings behind. It also will take any paint off in short order. The draw back to this stuff is it smells terrible, will burn you if you get it on you and don't get it washed off fairly quickly and will sometimes eat something you didn't want damaged. We won't talk about disposal...
An ultra sonic cleaner graced my shop over the past few days, and several parts have been cycled through it. One of which was the carb off of the lawn mower. Two cycles through the US cleaner, and it did every bit as good as the Chem Dip ever did without the fuss and smell. Used warm water and Simple Green in a 5:1 ratio (4:1 would probably do better, but I am low on the green stuff). Followed the US cleaner with a rinse and blow. "Why didn't I get one of these years ago?"