Question...
okay,..ranty question...
If the purpose of the vacuum petcock is to prevent a stuck float from being able flood the bike while parked... isn't the flood going to instead occur after you get underway?...and wouldn't you rather breakdown in any parking lot, rather than on the road?...
And,.. if the vacuum diaphragm prevents such flooding, but when it fails it, automatically causes it,... is that a gain?...
and on top of that,... the flow is much stronger, and more direct, down the vacuum line, than through the float needle so it makes a worse one...
Now,... in an accident, if the bike ends up on it's left side and the float needle sticks, it will shut off the flow, as long as the engine dies when the bike goes down,... but gas will still leak out of the tank vent and the full float bowl ...
(if the bike falls on the right side, no gas will flow from the petcock anyway)...
So, basically as far as I can see,... it's a non-solution to an unlikely problem, with the side effect of adding cost and complexity, and giving a better way to cause the same problem it is designed to prevent in the case of failure... which it has a known propensity to do...
Huh?...
...
PS,... and on top of all that, it's fugly, and makes the tank hard to get off...