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    petock question

    so i just bought a new petcock because my old one was impossible to turn, like i had to use a wrench to turn it! I just put my bike back together after a carb clean and tank repair. once i added gas back to the tank, it just started to flood out of the carbs. i tried shutting off the petcock but no matter what setting i was on it would still flow out. I thought that if it was on run or res that it would only flow out if the engine was on, and prime it would flow continuously. is there something i should check to make sure it is assembled correctly?
    1981 Suzuki GS450T

    Josh

    #2
    What petcock did you purchase? With a properly functioning OEM petcock there will be no flow without vacuum pulling on the vacuum port unless the level is set to Prime.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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      #3
      i got it off ebay. thats what i thought, might have to run some tests. thank you
      1981 Suzuki GS450T

      Josh

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        #4
        quick question the old petcock had the vaccuum line coming off the back at a downward angle, the new one has it at an upward angle. does this make a difference?
        1981 Suzuki GS450T

        Josh

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          #5
          Originally posted by SilentRaven View Post
          quick question the old petcock had the vaccuum line coming off the back at a downward angle, the new one has it at an upward angle. does this make a difference?
          No difference.
          Ed

          To measure is to know.

          Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

          Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

          Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

          KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

          Comment


            #6
            A brand new petcock should work the way it's supposed to right out of the box. Taking it apart to find out why it's not working isn't a good idea, you should return it for a different one. If you open it up and there's signs that you DID, getting it replaced free of cost probably isn't going to happen.

            As to the direction the vacuum line is pointing, I'm not sure that's an issue if it works like it should. If it where me, I'd see how the seller wants to handle getting a replacement sent out. I'd expect them to want to see the original first, that's fair for them.
            1980 Yamaha XS1100G (Current bike)
            1982 GS450txz (former bike)
            LONG list of previous bikes not listed here.

            I identify as a man but according to the label on a box of Stauffers Baked Lasagne I'm actually a family of four

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              #7
              thanks guys, took the bike apart again today and found out the main gas line to the carbs was not seated properly. Also tested the old and new petcocks, new one works fine old one does not. To test them I made a mini 'gas tank' out of a old bean can and attached the petocks to the bottom of it, and then filled it with gas and checked the settings. also sucked on the vacuum line to test that as well. got everything back together and seems to be running fine, no leaks!
              1981 Suzuki GS450T

              Josh

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                #8
                What petcock did you purchase? There are some Ebay OEM copies that are quite cheap. It would be good to have some evidence that one of them works...
                1980 GS1000G - Sold
                1978 GS1000E - Finished!
                1980 GS550E - Fixed & given to a friend
                1983 GS750ES Special - Sold
                2009 KLR 650 - Sold - gone to TX!
                1982 GS1100G - Rebuilt and finished. - Sold
                2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

                www.parasiticsanalytics.com

                TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

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                  #9
                  To test them I made a mini 'gas tank' out of a old bean can and attached the petocks to the bottom of it, and then filled it with gas and checked the settings
                  No test is useful unless the vacuum petcock on RUN/RESERVE can hold back against a full tank mounted on the bike.

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                    #10
                    I don't think I've ever had one that leaked with a full tank that didn't leak with a gallon or two in the tank as well... Just personal experience.
                    1980 GS1000G - Sold
                    1978 GS1000E - Finished!
                    1980 GS550E - Fixed & given to a friend
                    1983 GS750ES Special - Sold
                    2009 KLR 650 - Sold - gone to TX!
                    1982 GS1100G - Rebuilt and finished. - Sold
                    2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

                    www.parasiticsanalytics.com

                    TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

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                      #11
                      I have. Particularly an Ebay vacuum tap. worked fine with half a tank-but let gas past it with more. The spring was too weak to offset the increased pressure.

                      Because,as a rule, Pressure increases with depth.
                      Last edited by Gorminrider; 05-01-2020, 09:20 AM.

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                        #12
                        Boy this was a timely thread!
                        I'm going to test my petcock on the tank with fuel before I put it back on the bike!!!
                        1979 GS850 G
                        1979 GS1000E Resto moded
                        1993 Kawasaki ZR1100


                        The most effective means of preventing tyranny is to illuminate, as far as practicable, the minds of the people at large, and more especially to give them knowledge of those facts. - Thomas Jefferson

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