Does my Special have Auto-Off Petcocks?

[hollywoodxs11sf]

Hey, guys. I've seen numerous posts regarding petcocks, and I'm confused.

Does my '79 XS1100SF Special have vacuum-operated, Auto-Off Petcocks?

I've got the original setup with the octopus and all. My petcocks have an "Off" position.

When the lines are disconnected and I set the petcocks to anything but "Off", gas comes out. Should it? Do I need to rebuild my petcocks?

I haven't had any gas leak problems since I redid the carbs, which included all new floats, needles & seats (to the tune of over $475 at the Dealer).

Can anyone explain how this system works? It confuses me. Why the octopus? What does it do? Should I be turning my petcocks off when I park?

[Dennyz]

Yes and no. The petcocks are not vacuum operated, but there is a vacuum operated junction assembly under the tank (the octopus). If everything is operating correctly, you do not need to shut the petcocks off.

The off position is so you can take the tank off without leaking gas.

[John]

The petcock for a Special has 4 postions. On, Off, Res, and Prime. To select a function, the handle of the petcock should cover the disired function. In other words, the word ON that is stamped in the chrome ring that is on the petcock should be covered up by the petcock handle. Fuel will flow from any position but OFF. It will just flow from different ports. The front port is Prime, and the rear is Run, and Reserve. Handle pointed down, ON...pointed up...Res...to the front...Off, and to the rear, Prime. The octopus is a distribution / shut off valve. It is vacuum actuated. The vacuum source is the nipple on the #1 carb boot. The octopus is bypassed in Prime mode by the the way the thing is plumbed. The Prime hose T's into the fuel line that is downstream of the octopus. Are ya good and confused yet? I have mine removed and I can run one just one petcock.

[hollywoodxs11sf]

Aaaahhhh. Now I see. Thanks, John! I was about to spend $28 on a rebuild kit, but I now understand how things work down there. I guess mine's working fine, as I don't have gas coming out of my airbox or any of the other problems it would bring.