28mm Mikuni - What are these lines

[Joe6v6]

I assume these are the stock carburetors,77 RD400, what are the inlets in the middle. Are they overflow for the float bowl? What are the other 2 smaller diameter inlets? Where should I run these lines to. Seems very difficult to find a diagram of all the lines that come off these carbs. 

[SoCal250]

Joe,
The two large upward angled nipples on the inboard side of the carbs are bowl vents. They were originally connected with a hose to the airbox. I just connect a short piece of hose to mine and let them hang down. Some people who are running a Y-boot instead of the stock airbox drill holes in the bottom of the boot, add nipples, and run hoses to them. A third option is you can remove the brass ball in the bottom of the bellmouth covering the airjet, clean the jet, then block off the vent tubes. Do not block the vent tubes unless the airjet has been unshrouded.

The two smaller nipples on the bottom of the bowls are fuel overflow for the float bowls.

[LMS]

On another note, you might want to think about getting pod filters that don't have the end caps.