TOPIC:

Thinking about buying an ultrasonic cleaner. Going to clean some old carbs.
What is the best solution to use?

I was thinking of the same thing. I took advice from others here and completely disassembled them and soaked them in diesel fuel for a week then I soda blasted them and painted them. Make sure all the passages are clear buy using Patton's VM28 cleaning process. You can download it HERE

Here is how mine turned out.

I've used Pinesol in my ultrasonic cleaner.
I put in a whole bottle, then topped up the level with water.
Probably 80%+ Pinesol to 20% water.

That worked really well on some really gummed up carbs.
Simply green did not work well.

I used Simple Green straight up in a heated ultrasonic cleaner to clean a Kohler carb. That's all I've done so far, and it seemed to work ok.

Not perfect, not even real well, but an ok job. I'm sure there are better things to use.

Just plain old hot water works well.
The ultrasonic isn't a one hit cleaning process, Use it as the final stage in the cleaning process after degreasing etc and finish off with compressed air.
Parts should be FULLY dismantled prior to cleaning then use brush and solvent etc to remove oil, grease and grime etc.
Trying to remove grease and soft deposits in the ultrasonic doesn't work well as they just absorb the shockwaves produced by cavitation.

That's interesting. I've been cleaning carbs all week in the dental grade unit I bought. Works like a hot damn, especially on the crudded up grease-ridden ones. I usually have to hit a stubborn spot or two afterwards, with a soft baby toothbrush, but other than that, they're golden.
What you said makes sense, but it hasn't been my experience.

Think I will start with Pinesol. Its easy to put on the grocery list!!!

hot water and simple green usually works best for me. I have used the industrial grade solution and it does work better but it is expensive.

simple green, purple power, even dish soap, work pretty well.