One thing you should try , turn the idle knob in several turns and see if it will start or at least chug, if it is not pushing against the butterfly plates will not open , hence no fuel into cylinder. You have stated you were trying brake cleaner to try to start , starting fluid is best to use. You can also do a bench synch, I take two business cards cut in half , put one piece under each butterfly plates , try pulling card out with slide drag if to much or not enough starting at carb 1 turn synch screw in or out till you get a slight drag ,move on to carb 2 , and carb 4 , carb 3 is controlled with the idle knob . If you do this right , hold carb rack up to a strong light you will see a slight crescent moon at bottom of butter fly plate. From what you have stated to me it is fuel related problem , if you adjusted valve clearance that will help . Good luck.