Widget, I have been cleaning these cubes for well over 7 yrs and never used anything stronger than soap and water in my USC. Even household dish soap works for me. I actually use Dawn Ultra (about 8.5pH) many times even though I now a 12.5 pH non residual soap now. Yes it takes a few cycles and changing out the soap/water mix as it gets dirty. But low cost of dish soap makes change outs less costly. With dish soap you need run a water only rinse cycle.
It also advisable to pre-clean the exterior of the carbs which fuel mix works good and won't harm the carb but not good for you especially if you are a smoker. Don't want you to go boom.
