Re: Mysterious "t-piece" between carbs on '81 CB750K...

Posted by LukeM on Jan 27, 2012; 1:56pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Mysterious-t-piece-between-carbs-on-81-CB750K-tp3691494p3693338.html

I don't remember seeing this piece on my old CB750L.  It did have the fuel manifold valve, but if I recall that had one line hooked to a vacuum source, one fuel line in from the petcock, and one fuel line out to the carburetor fuel input rail.

Interestingly, my VT700C has a similar line between its 2 carbs, which is a pressure balance port.  It's connected to a long tube that's open at the other end.  If the end of that tube is in the path of moving air, the vacuum balance changes, and the bike gets all weird-running (normally around 40-45mph and faster).

I'm sure some digging around on the microfiches at bikebandit.com or maybe in the FSM will locate it.  If it were me, I'd ride a bit with the port open, then cap it off and ride it again.  Whichever makes it run better, go with that.

Luke M