When I have the carbs on a bench I use denatured alcohol instead of gasoline to check fuel levels in the carbs. Denatured alcohol is 10% denser than gasoline (0.79 v 0.71 g/ml), which is better than using water @ 1.0 g/ml. Less stinky and easier to handle and clean up afterwards.
When the carbs are still on the bike I just use the gas in the fuel tank.
Which reminds me, I have to check my float level in carb #2!
