Now...if the fuel is shut off how do the carbs over flow? There is no fuel flow.
I guess peacocks al and shutoff valves aren't needed.
Flame away.
well, for one thing, it's not just a "single" point failure.... i.e., fuel shutoff only....
Part 2 is a float needle tip not sealing against it's seat...
So, with all 4 floatbowls completely full of fuel, and the line running up to the fuel shuttoff also full of fuel, even tho the gas is "shut off"; if #1 piton is at the correct point, and intake valve opened, and the bike is sitting on the side stand, bike leaning over at an angle AND 3 float bowls now sitting progressively higher than the lowest one... #1..
with #1 float valve needle is not sealing..... fuel WILL flow from the remaining 3 carbs, back to the lowest point, #1 bowl.... AND, seeing as the bowl "vents" are routed up and behind, well above the carbs, fuel will flow up, and into the #1 intake, until the point the 3 remaining carbs, and fuel line, have dropped below the level of the carb bore/throat... ...
I've had it happen a couple times times on one of mine... once it locked, and when the starter was hit a second and third time, it did start... and spit rich fuel out the exhaust.... another time it just topped rotating... and did not turn over...did I bend a rod...? I dunno, never looked... but the engine DID refuse to turn over, until I removed the plugs, and cranked it to remove the fuel from the piston area.