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Rebuild or replace vacuum petcock?

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  • Rebuild or replace vacuum petcock?

    Having owned a Suzuki GS series bike in the past one of the questions that often comes up is the vacuum petcock and it seems my newly acquired SX has the same issue. The GS crowd seems to pretty much be in agreement that it's difficult and really not worth while to try to rebuild a vacuum petcock since it rarely works as intended afterward and you're better off replacing it with a high quality one, NOS or equivalent, not a cheapy unit. My XS has the octopus removed with each petcock feeding two carbs which seems to work fine by me but one of them is no longer shutting off, it's "On" all the time. Personally I like the idea of keeping things a no-brainer and letting the vacuum do the job of shutting off the petcock but the price of going "Manual" is too hard to ignore so here are my questions: Is there a "best" method to rebuild these petcocks? Is it even worth trying? What is my best source if I decide to go with a new vacuum petcock? Thanks in advance!
    1980 XS1100G

    These aren't my words, I just arrange them

  • #2
    I went to manual on my Special, after removing the Octy. It's a lot easier, and now that I have GOOD fuel line, it runs well. I don't remember who I bought them from, but I think it was an Ebay dealer. Remember, the Standard and Special are TWO DIFFERENT bolt patterns for the petcocks, so make sure you are getting the correct one for the tank you are using! I am running a Standard tank on my Special, so I have more of a range. I also have the Vetter fairing and box on it.
    Ray Matteis
    KE6NHG
    XS1100 E '78 (winter project)
    XS1100 SF Bob Jones worked on it!

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    • #3
      The vacuum fuel valve on my XS650 works just fine. I've had the bike for 39 years and never had a problem with it. I've had the Eleven Special since 2003, so someone else took care of it before me. The vacuum shutoff (octopus) stopped working as in failed to close. I rebuilt it and it has been doing fine for years. I think some of the kits come with an o'ring that has too small a cross section. That's easy enough to correct.

      Here's a helpful link: Rebuilding the Yamaha Vacuum Fuel Valve w/pics

      Marty (in Mississippi)
      XS1100SG
      XS650SK
      XS650SH
      XS650G
      XS6502F
      XS650E

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      • #4
        Originally posted by jetmechmarty View Post
        I'd have never thought to polish up that sealing seat, clean yes, polish no. Thanks for the link!

        1980 XS1100G

        These aren't my words, I just arrange them

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        • #5
          I have never owned a standard and have never had to rebuild or deal with the vacuum petcock. I have and always will keep the Octy on my specials. I like the idea when it is functioning properly that I have another safeguard against a flooded crankcase and spun bearings. I always shut off my petcocks when I park the bike though. Even if just going into a store they are shut off. Just a habit for me and I do that on all of my bikes that have carburetors.
          2 - 80 LGs bought one new
          81 LH
          02 FXSTB Nighttrain
          22 FLTRK Road Glide Limited
          Jim

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          • #6
            How do you shut off a vacuum petcock when it has no off position? Since you personally have never had a problem with a petcock does this mean that others automatically won't as well? If you where to have bought a bike three weeks ago with no octopus on it would you install one? Guess I'm trying to understand what you're adding to the conversation here....
            1980 XS1100G

            These aren't my words, I just arrange them

            Comment


            • #7
              Originally posted by LAB3 View Post
              How do you shut off a vacuum petcock when it has no off position? Since you personally have never had a problem with a petcock does this mean that others automatically won't as well? If you where to have bought a bike three weeks ago with no octopus on it would you install one? Guess I'm trying to understand what you're adding to the conversation here....
              cajun31 has Specials. Specials have manual petcocks rather that the vacuum taps on the standard. The Special also has a single point vacuum shutoff valve (octy or spider valve) installed as a safety device. Speaking for myself, I would return the bike to stock if it were missing. I'm a fan of safety devices involving gasoline. Older bikes with manual taps have no such devices, so those familiar with bikes predating those devices often have no issue removing them, especially in the case of the Eleven Special that involves extra plumbing.
              Marty (in Mississippi)
              XS1100SG
              XS650SK
              XS650SH
              XS650G
              XS6502F
              XS650E

              Comment


              • #8
                Originally posted by jetmechmarty View Post

                cajun31 has Specials. Specials have manual petcocks rather that the vacuum taps on the standard. The Special also has a single point vacuum shutoff valve (octy or spider valve) installed as a safety device. Speaking for myself, I would return the bike to stock if it were missing. I'm a fan of safety devices involving gasoline. Older bikes with manual taps have no such devices, so those familiar with bikes predating those devices often have no issue removing them, especially in the case of the Eleven Special that involves extra plumbing.
                thanks for clarifying for me Marty. I thought my opening comment would have indicated that, however, I probably assume too much. One other tidbit that I know I have read on here somewhere over time is that the vacuum petcocks can be modified to add an off position How to easily add an "off" to your standard's petcocks - XS11.club Forums
                Last edited by cajun31; 05-28-2022, 05:24 PM.
                2 - 80 LGs bought one new
                81 LH
                02 FXSTB Nighttrain
                22 FLTRK Road Glide Limited
                Jim

                Comment


                • #9
                  No dream. There’s a gate that can be filed off.
                  Marty (in Mississippi)
                  XS1100SG
                  XS650SK
                  XS650SH
                  XS650G
                  XS6502F
                  XS650E

                  Comment

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