I had this problem too, managed to avoid a carb removal. After doing the gumout through drain trick above, I added a fair bit o' Seafoam to my tank, ran it for a minute to get the solvent-laden gas into the carbs, shut it off. Every 15 minutes for the next few hours (I was working outside) I hammered on the carbs with a screwdriver handle, then ran it for a minute. Eventually, the combination of tricks loosened it up to where it would run reasonably well, then an easy ride finished clearing it out. Good luck!