"80 Special "octy" question

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  • 650mark
    XStremely XSive
    • Jul 2012
    • 307
    • Mesa, Az.

    #1

    "80 Special "octy" question

    2 of the hoses coming from the "octy" to the petcocks supply fuel but why the 2 "vacuum" hoses also going to the petcocks? what do they do? thanks
  • natemoen
    Master of XSology
    • May 2010
    • 8640
    • Fargo

    #2
    There are 2 fuel lines on each of the special petcocks. Only 1 vacuum line, and that goes to the octy.
    Nathan
    KD9ARL

    μολὼν λαβέ

    1978 XS1100E
    K&N Filter
    #45 pilot Jet, #137.5 Main Jet
    OEM Exhaust
    ATK Fork Brace
    LED Dash lights
    Ammeter, Oil Pressure, Oil Temp, and Volt Meters

    Green Monster Coils
    SS Brake Lines
    Vision 550 Auto Tensioner

    In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

    Theodore Roosevelt

    Comment

    • BA80
      Doctor of XSology
      • Oct 2010
      • 9980
      • Tulsa, Ok

      #3
      Originally posted by 650mark
      2 of the hoses coming from the "octy" to the petcocks supply fuel but why the 2 "vacuum" hoses also going to the petcocks? what do they do? thanks
      If you have vacuum hoses going to the petcocks you either have a standard tank on there or you have vacuum lines hooked to fuel outlets. On the special petcocks there is an regular outlet at the rear and a prime outlet on the front on each side. They are both the same size.
      How about a picture of what your talking about?
      Last edited by BA80; 10-25-2013, 06:15 PM.
      Greg

      Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

      ― Albert Einstein

      80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

      The list changes.

      Comment

      • 650mark
        XStremely XSive
        • Jul 2012
        • 307
        • Mesa, Az.

        #4
        you just answered my question. both of my petcocks have on, off, reserve, and prime. now I understand that those other 2 hoses provide fuel when in prime position. now I get it. thanks.

        Comment

        • BA80
          Doctor of XSology
          • Oct 2010
          • 9980
          • Tulsa, Ok

          #5
          Greg

          Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

          ― Albert Einstein

          80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

          The list changes.

          Comment

          • 650mark
            XStremely XSive
            • Jul 2012
            • 307
            • Mesa, Az.

            #6
            thanks again for the info and the diagram of the fuel hoses. i'd like to buy a spare rubber vacuum valve inside my octy assembly but I can't find a part number anywhere. partzilla shows only the complete assembly. any clues? thanks

            Comment

            • natemoen
              Master of XSology
              • May 2010
              • 8640
              • Fargo

              #7
              If you get a petcock rebuild kit for the specials it usually comes with the octy diaphragm as well.
              Nathan
              KD9ARL

              μολὼν λαβέ

              1978 XS1100E
              K&N Filter
              #45 pilot Jet, #137.5 Main Jet
              OEM Exhaust
              ATK Fork Brace
              LED Dash lights
              Ammeter, Oil Pressure, Oil Temp, and Volt Meters

              Green Monster Coils
              SS Brake Lines
              Vision 550 Auto Tensioner

              In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

              Theodore Roosevelt

              Comment

              • BA80
                Doctor of XSology
                • Oct 2010
                • 9980
                • Tulsa, Ok

                #8
                Greg

                Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

                ― Albert Einstein

                80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

                The list changes.

                Comment

                • 650mark
                  XStremely XSive
                  • Jul 2012
                  • 307
                  • Mesa, Az.

                  #9
                  thanks again for the help

                  Comment

                  • jetmechmarty
                    Master of XSology
                    • Nov 2003
                    • 7765
                    • Coldwater, Mississippi

                    #10
                    Keep in mind that a leaking vacuum fuel valve is usually caused by a bad seat or o'ring. Make sure you get that seat smooth as a baby's bottom.
                    Marty (in Mississippi)
                    XS1100SG
                    XS650SK
                    XS650SH
                    XS650G
                    XS6502F
                    XS650E

                    Comment

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