A caustic bath is generally the province of professional cleaning and stripping services, but you can buy the materials and do it yourself. Be very careful with this material, because it's hazardous at the best of times.
Warning! Any caustic bath cleaners will dissolve aluminum like sugar into hot water. So be absolutely sure of anything you put into a caustic bath - especially carburetors, which are made of an aluminum alloy. Also, be aware that cadmium-plated or nickel-plated parts are likely to lose their plating in this kind of treatment - that's how nasty it is!
In general, if you've reached this stage trying to clean a part, you're probably better off leaving this kind of material to the pros.