Somehow got it in my head that making a home made anemometer to sync my carbs was a good idea.  In principle this will work if the fluid you’re using is a) heavy enough, and b) your carbs aren’t so out of balance that when you turn the bike back on the cylinder with the most vacuum sucks the fluid right into the engine.

Ended up just buying a set of 4 gauges online for about $65.  Works fine & easy to use.  But for kicks, this was the “home made $1.50 carb sync tool” you can find on the internet.