How good is the snap back on your throttle. If you have a good solid snap back try using it to shock the carbs if you get my meaning. Not likely but worth a try.
If you can get to the bowls, just give them each a good tap.You could turn your fuel off and use the drain screws on the bowls to drop the fuel and try doing it dry if it doesn’t work at first.
If no success with that, then it’s strip tank off time and time to get whiffy.
Best of luck mate