need confirmation that I'm on the right track

I have been reading through old threads trying to find an answer for what ails my bike. I think I have found it but need some confirmation. There are three nipples coming off the petcock. One is obviously to the fuel pump. Another goes to cylinder two for vacuum. I'm not positive about which nipple this is and would appreciate input. The third nipple appears to bo nowhere. Is this correct? This bike sat in a garage for 5 years before I got it and was disassembled from the tank through the carbs. I think I have most things pieced together again but gas is coming out of the petcock when I turn it to the "on" or "res" position. I have deduced that I need to at least replace the diaphragm in the petcock.

I just need someone who knows more than me to tell me that I am on the right track. Thank you.

Dan

 

Third nipple should just be a vent.

See here: http://www.daughertymotorsports.com/
Choose - How To \ Fuel Tank Valve Modification

 

Thanks MasonV45. I appreciate it.