Rear cylinder head vacuum line?
 

When I pulled the rear head on my bike there is a length of vacuum line attached to a nipple on the exhaust side of the head. It wasn't going to anyhthing when i pulled it off and don't know where it's supppose to go to. It's not on the front head.

Does this sound familiar to anyone?

it's the vacuum line for the petcock.

Thanks, that would explain why it wasn't connected to anything.