Wanted to add a fun little tidbit regarding wet testing the float system. A gravity fed, remote tank hanging from above, I installed an inline fuel valve (petcock) to enable OFF or ON flow as needed.
Carbs hooked up (bowls dry), when valve flipped to ON....I listen for what I call the "toilet flush"
....liquid quickly filling the fuel pathways, into and past the float valves and bowls quickly filling. There is a distinct sound involved, as a result, I then know the float valves are functioning in "inlet or fill mode"
I'm then checking for any leakage anywhere, letting them sit a bit, bowls filled. As I've renewed all fuel inlet and vent rail and bowl orings, this is rarely a problem, though an occasional broken rail will drip...followed by replacement.
Then follows the actual fuel level test...opening the drain bolt with tubing attached.....I'm looking for float valves to restrict the fuel height to prescribed levels, equal between the 2. Sometimes tweaks are called for, have run into a defective float valve, rare but does occur....hey, thats why I'm checking. Want to make any and all repairs and adjustments needed PRIOR to actual installation on the bike.
If levels are ok, the float valves have now proven themselves ok in "stop mode"....let 'em sit loaded for a bit.
In order to confirm, I've developed ways to repeat the refill/level/stop mode test without full drain, disassemble, toilet flush repeat.
As I choose to test prior to final, full carb parts assembly, I then disassemble yet again (double work, but thats ok), reclean, blow and air dry, then later go forward to final full assembly phase.
Fun poop. I believe I've long ago developed an effective, efficient methodology and got it down to "routine".
A full takedown, split, machine assist refurb, testing, reassembly is about 5 hours total labor on 250 and 500 twin carbs. Ducati/Mikuni twin somewhat longer. 4 bangers double that, if not longer.
I admit it, I'm a carb nerd all right.