Parts Washer cleaner

Little parts, like from a carburetor, I soak in a special cleaning fluid you buy at auto parts. It comes in a 1 gal metal paint can w/ a strainer basket inside. I have also soaked pistons one at a time in it, with a plastic bag taped over (1 per night). It has something floating on top to limit evaporation. Smells nasty, but doesn't hurt aluminum.

Another idea is SuperClean, which you can buy at Walmart. I think it is a strong alkaline water-based solution. I used it to remove paint & chrome from plastic dash trim, which is an idea I found on plastic model web sites. Works great for that. Haven't tried on steel parts. I did hold down the plastic with an aluminium chunk and it attacked that, so don't try on aluminum.