So, it turns out it wasn't water:
I had a mechanic take a look at it this week, and he found that the spark plug was fouled up because the carbs were soaking it with fuel . . . (so they cleaned the carbs, which is what I started out to do in the first place) . . . but the reason the bike wouldn't start was because it had lost compression because the valves were all f*!@$d up. So they fixed that, too.
Almost $400 later, I'm psyched to pick up my bike tomorrow and see what it feels like to ride one of these bikes with an engine that *works*!!!
And at $90/hour, I'm more committed than ever to doing as much of my own wrench work as possible!
Thanks to everyone on the board who offered helpful words!