I've got an ultrasonic cleaner,and I was not impressed with the results .
I used a cleaning solution specifically for aluminum, and it turned the carbs a dark color, a lot of polishing later, to get them looking good again .
I would soak them in a carb cleaner ' dip tank', most common available here in the US, is Berryman's, looks like a gallon paint can full of carb cleaner, and a fine mesh basket to contain the small parts .