correct on both accounts from my experience but, my sonic cleaner is a harbor freight special. I tried pinesol and super purple or what ever it is called. There was dirt on the tank floor, but the carb was still dirty. One may have better luck with a higher grade model though. All carb dips are methyene chloride. Paint stripper and it doesn’t clean the green meanies off. I got pissed after the third dip so I left the carb in the dip for a week. It ate away the casting. Good thing it was a worthless carb, that time I was smart enough to experiment before I dipped a good carb in.
Now I worked in a motor cycle shop for a summer a few years ago and I swear the good dip is dicloromethane but I’m just not sure. You can get a 5 gallon pail of that stuff at a chemical supply warehouse but is not cheap and how do you dipose of it after your done? Its damn nasty ****, rubber gloves and respiratory nasty. But most of all I’m just not sure thats the stuff. And I don’t need the department of homeland security showing up instead of a 5 gallon pail of it, you know what I mean.