carb terminology

[Soloratov]

Just curious what the "carb body size" applies to, and the "throat depth".

I know I have the Mikuni BSR34's, so I assume that means the size is 34mm. What about throat depth? Distance from outside edge to.....?

Separate question about carbs. I have seen some people on here mention removing the vacuum tube and capping the port, and then just running the bike on PRI. Is there a reason for this, or is it just if the petcock is acting up?

[Paulcet]

Just if the petcock is acting up.