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    Fuel Leak

    My 1980 GS750L started leaking fuel. I walked out into garage and there was a puddle of fuel on the floor. It appeared to be leaking from the ignition cover. Without doing an extensive inspection I believe the fuel is leaking from the carb bowls. I had notice a small leak from them last month after a very short ride around the block. The bike is new to me and I was told the carburetors had been rebuilt. I'm thinking the petcock is not doing its job and allowing fuel down into the carbs, it overflows, finds it's way down to the ignition cover and drips out the weep hole in the bottom. Bike is on it's center stand. I placed a pan underneath to catch drips. I welcome any thoughts on this.

    sigpic
    1980 GS750L

    #2
    For one thing, make sure your petcock shuts off the flow of fuel when the engine is turned off. And don't leave your petcock on the prime position.

    Secondly, needless to say you need to pinpoint the source of leakage. The most common reason is because of a blocked or worn out float valve in one or more of the carbs. There is a carb rebuild tutorial linked in my signature which may help you.

    Lastly, never trust anything the previous owner says about the maintenance status of your bike. Learn for yourself.
    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


      #3
      You didnt leave the petcock in PRIme position did you?
      If so, that is your problem.

      THe carb float needles cant be expected to complelty shut off gas flow, so the auto petcock provides that function (but cant if you leave in PRIme position).
      Pull/pry the big line off the petcock, see if the petcock is shutting completly off.

      Other concern: Might now be gas in your crankcase oil.

      >>Later note:
      Oh, an L.
      Some of those petcocks dont have a lever. . . . . not sure which do or dont.
      Last edited by Redman; 12-08-2021, 03:06 PM.

      Had 850G for 14 years. Now have GK since 2005.
      GK at IndyMotoGP Suzuki Display... ... GK on GSResources Page ... ... Euro Trash Ego Machine .. ..3 mo'cykls.... update 2 mocykl


      Comment


        #4
        If your petcock looks like one in this eBay link, be suspicious ….and understand how it’s supposed to work
        80-81 GS850 GLT GS850L GS850GLT. 80-81 GS1100 ET/LT GS1100E GS1100L GS1100ET GS1100LT. 80-81 GS1000 ET GS1000E GAS1000ET. 1980 GS1000 ST GS1000S GS1000ST. 80-81 GS750 ET GS750E GS750ET. 80-81 GS750 LT GS750L GS750LT.
        1981 gs650L

        "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

        Comment


          #5
          Yes, an "L" with no lever. vertical slot=Prime, horizontal =Run. yes? if so... then I was in prime. I set it to run using a very narrow flathead screwdriver. The bike is in for the winter and I plan on replacing all fluids before riding next year.

          sigpic
          1980 GS750L

          Comment


            #6
            Still can't imagine anybody would ever design such a (don't want to say STUPID but can't think of a better word) pet cock. Mine had the PRI kind'f at a diagonal location, neither vertical nor horizontal, just had to guess at it. Thankfully it only lasted a yr. or so.
            1983 GS1100E, 1983 CB1100F, 1991 GSX1100G, 1996 Kaw. ZL600 Eliminator, 1999 Bandit 1200S, 2005 Bandit 1200S, 2000 Kaw. ZRX 1100

            Comment


              #7
              Originally posted by tom203 View Post
              If your petcock looks like one in this eBay link, be suspicious ….and understand how it’s supposed to work
              https://www.ebay.com/itm/New-Petcock...-127632-2357-0

              Yup, That's it.

              sigpic
              1980 GS750L

              Comment


                #8
                Originally posted by Pete Wrigley View Post
                Yup, That's it.
                The service manual describes how that petcock functions.

                With the slot in the prime position a pulse of vacuum from the engine pulls the internal diaphragm open, and a check valve holds it open until the slot is turned back to the run position.
                Last edited by Nessism; 12-09-2021, 08:43 AM.
                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


                  #9
                  This forum is so great. I appreciate all the help guys. From the little I've read so far the reason for this type of petcock has something to do with the bike having a fuel gauge. I'm not sure of all the technical detail behind it. Can I just leave it in the "run" position?

                  sigpic
                  1980 GS750L

                  Comment


                    #10
                    Originally posted by Nessism View Post
                    The service manual describes how that petcock functions.

                    With the slot in the prime position a pulse of vacuum from the engine pulls the internal diaphragm open, and a check valve holds it open until the slot is turned back to the run position.

                    That's interesting. I would have figured it to operate the same as others. Turn to PRIme and fuel flows. I'd be the one to try and prime the bowls while putting my gear on and then hit the start button. This makes me even more thankful for the later model G design.




                    Originally posted by Pete Wrigley View Post
                    This forum is so great. I appreciate all the help guys. From the little I've read so far the reason for this type of petcock has something to do with the bike having a fuel gauge. I'm not sure of all the technical detail behind it. Can I just leave it in the "run" position?
                    Originally posted by Redman View Post
                    You didnt leave the petcock in PRIme position did you?
                    If so, that is your problem.

                    THe carb float needles cant be expected to complelty shut off gas flow, so the auto petcock provides that function (but cant if you leave in PRIme position).
                    Pull/pry the big line off the petcock, see if the petcock is shutting completly off.

                    Other concern: Might now be gas in your crankcase oil.

                    >>Later note:
                    Oh, an L.
                    Some of those petcocks dont have a lever. . . . . not sure which do or dont.
                    Roger

                    Current rides
                    1983 GS 850G
                    2003 FJR 1300A
                    Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                    Comment

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