Have a Bransonic commercial grade ultrasonic cleaner that can do a complete in-line four rack at once (disassembled of course). It heats to 165 degrees and has a full range of adjustability in terms of time, heat and cavitation. Because it is dedicated to be used as a carb cleaner I only use Omega Clean as a solvent (i'm not an employee or salesperson, have just been very pleased with the results)as it contains no acids, as well as using only distilled water.
Have heard alot from members about how effective the HF units are and can only smile when I read the responses as I owned one many years ago and it was garbage. A buddy bought one last year for $60, thought he was getting a bargain and ended up really dissatisified with the results as well. Yes they clean to a point but without high heat and a really powerful cavitation you're really only getting superficial results.
A simple test of a units effectiveness is the tin foil test. Take a small piece of 3" x 5" foil wrap it over a piece of wood dowel and hang it into the ultrasonic unit, set the unit on full power/heat (if you have it) and run it for a 60 sec test. A properly functioning USC will dimple the foil and a commercial level unit will make it look like its been shot with bird shot (holes and all). The HF unit will barely make a mark in the foil.
Many of the solvents members are using as cleaning agents contain acid and will breakdown the surface of the carb and lead to excessive oxidation and eventual deterioration. Always use a cleaner formulated to be used with aluminum otherwise flash rusting and contamination of the metal will occur with acid based cleaners.
Been reading as well to "never put metal float bowls into a heated USC" or it breaks down the bond of the overflow tube". Been doing carb service/rebuilds/cleaning for over 20 years and have never had 1 carb come back with leaking tubes. We leak test all tubes before and after cleaning and the only ones that leaked after cleaning leaked before they were cleaned.
Hope this information was helpful, if any members have questions about USC or my services feel free to send me a PM and would be happy to help in any way
Steve