When the carbs were "disassembled and cleaned", did you purchase carb kits? I've supplied a diagram of the carb. Items #4 and #5 absolutely must be removed so that you can clean, run a small wire through, and spray compressed air through the small passages beneath those lead plugs. You'll need to purchase carb kits so you can replace these plugs once you've cleaned the passages that they cover. Also, did your remove the jets, #35 (called an orifice in the diagram) and the hole that the screw #30 goes into. #35 often gets clogged if the motor sits for a while since any trash in the fuel settles to the bottom and as the fuel evaporates, these jets get clogged with the sediment. You need to clean the holes in these lower jets until you can see through the hole and see a perfectly round hole. Fuel fills the bowl of the carburetor, and that jet (orifice) allows gas to flow through into that raise round area in the middle of the bowl. On the bottom of the carburetor, there is a brass tube with a series of small holes in it that fits down into that raised center hole in the bowl of the carburetor. That's your emulsion tube. It sucks gas into the motor. The gas that gets sucked into that tube has to pass through that jet. If it's clogged, you get no fuel supply. On older motors that jet in the bowl #35 is very difficult to remove. A good way to see if it's good and clean is to shine a flashlight into the bowl of the carburetor and then look through the opening where the drain screw for the bowl is located and make sure that the light can be seen coming through the jet. The light must show a perfectly round circle.
