Petcock left on, bogs on standing start

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  • littleroot
    • Jan 2026

    #1

    Petcock left on, bogs on standing start

    I have not been back on the board for a while, busy with life and the bike has been running great until the other night when I left the petcock on and discovered some gas on the floor of the garage. I am talking about TOM_MLC's silver 80SG1100E. This has happened to me once before, and to Tom, too.

    She leaked a little gas on the ground and after I starting up I noticed was running really rough. I had same exactly experience when I first got the bike and after removing the tank and checking things out and putting it back seemed to cure it. Almost like air got in the gas line. But I have no idea as I'm a mechanical dufus. Anyway, this time, removing the fuel line from the tank and putting it back again, she was much better, running and idling just as it should but the difference is I now have to raise the revs way too much when I accelerate away from a standing start or she will stall. Sounds like carb sync but not sure how that would fall off so much just overnight. Also I think I have a compression problem on #3 cylinder: when I did a quick test a couple weeks ago it was only about 100 and the others around 125. Sigh. I don't have much time and money but it looks like I'm going to have to find a way.

    Advice please.

    Thanks, friends.
    -Bob
  • bccap
    Forum LongTimer
    Past Site Supporter
    • May 2011
    • 27260
    • Vancouver B.C.

    #2
    Any gas in the oil ?

    Comment

    • littleroot

      #3
      Originally posted by bccap
      Any gas in the oil ?
      How should I check for that?

      Comment

      • Agemax
        Forum Guru
        • Apr 2008
        • 8371
        • plymouth uk

        #4
        carb sync does not "just" go out for no reason. it is a mechanical setting and it only affects idling speed anyway. sounds more likely that you may have some dirt in the carbs.
        i would suggest taking them off and giving them a thorough clean
        1978 GS1085.

        Just remember, an opinion without 3.14 is just an onion!

        Comment

        • Steve
          GS Whisperer
          • Jun 2005
          • 35924
          • southwest oHIo

          #5
          I take it that this is not a stock vacuum-operated petcock?

          If it's not, then you obviously have a problem with at least one of your inlet needle valves in the carbs. They should be able to hold back fuel coming down the line.

          If your problem clears up after a bit of running, it's possible that one (or more) carbs simply flooded a bit, and running has taken that overflow down to its normal level.

          This would be either a lesson on turning off the petcock or installing a good vacuum-operated one.

          .
          sigpic
          mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
          hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
          #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
          #2 son: 1980 GS1000G
          Family Portrait
          Siblings and Spouses
          Mom's first ride
          Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
          (Click on my username in the upper-left corner for e-mail info.)

          Comment

          • bccap
            Forum LongTimer
            Past Site Supporter
            • May 2011
            • 27260
            • Vancouver B.C.

            #6
            Originally posted by littleroot
            How should I check for that?
            Look at the sight glass. If the oil is above it. Drain a little off and inspect it.

            Comment

            • littleroot

              #7
              Originally posted by Steve
              I take it that this is not a stock vacuum-operated petcock?

              If it's not, then you obviously have a problem with at least one of your inlet needle valves in the carbs. They should be able to hold back fuel coming down the line.

              If your problem clears up after a bit of running, it's possible that one (or more) carbs simply flooded a bit, and running has taken that overflow down to its normal level.

              This would be either a lesson on turning off the petcock or installing a good vacuum-operated one.

              .
              It just has one line on the petcock so yes I think you are correct, not vacuum.

              I will look into a different petcock. Should I contact Z1 for advice on selecting one?

              Thanks,
              -Bob

              Comment

              • littleroot

                #8
                Originally posted by bccap
                Look at the sight glass. If the oil is above it. Drain a little off and inspect it.
                OK, will do.

                Comment

                • bccap
                  Forum LongTimer
                  Past Site Supporter
                  • May 2011
                  • 27260
                  • Vancouver B.C.

                  #9
                  Part number 3 and 4. If that is the problem, or you don't want to have to remember to turn it off.

                  http://www.boulevardsuzuki.com/fiche...1980&fveh=2155

                  Comment

                  • littleroot

                    #10
                    Originally posted by bccap
                    Part number 3 and 4. If that is the problem, or you don't want to have to remember to turn it off.

                    http://www.boulevardsuzuki.com/fiche...1980&fveh=2155
                    Holy Schnike, not cheap!

                    Thanks

                    Comment

                    • bccap
                      Forum LongTimer
                      Past Site Supporter
                      • May 2011
                      • 27260
                      • Vancouver B.C.

                      #11
                      Yeah, and I don't see a vacuum hose on it either. Perhaps someone with an 80 1100E will explain.

                      Comment

                      • Steve
                        GS Whisperer
                        • Jun 2005
                        • 35924
                        • southwest oHIo

                        #12
                        Originally posted by bccap
                        Yeah, and I don't see a vacuum hose on it either. Perhaps someone with an 80 1100E will explain.
                        I don't have an '80 1100E, but I can tell you that the vacuum hose is part #79 on the carb fiche.

                        .
                        sigpic
                        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                        #2 son: 1980 GS1000G
                        Family Portrait
                        Siblings and Spouses
                        Mom's first ride
                        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                        (Click on my username in the upper-left corner for e-mail info.)

                        Comment

                        • Guest

                          #13
                          Take a pic of the petcock.
                          I don't think Tom would keep that POS stock 80 petcock.
                          I would change your oil and filter since more than likely you have fuel in your oil. This is not like peanut butter in my chocolate.

                          Comment

                          • bccap
                            Forum LongTimer
                            Past Site Supporter
                            • May 2011
                            • 27260
                            • Vancouver B.C.

                            #14
                            Originally posted by Steve
                            I don't have an '80 1100E, but I can tell you that the vacuum hose is part #79 on the carb fiche.

                            .
                            I don't see a part 79. But I think I know what you mean. The two petcocks shown are just different views of the same one ? I wasn't sure as each has a different cost and listing number.

                            Comment

                            • Steve
                              GS Whisperer
                              • Jun 2005
                              • 35924
                              • southwest oHIo

                              #15
                              Originally posted by bccap
                              I don't see a part 79. But I think I know what you mean. The two petcocks shown are just different views of the same one ? I wasn't sure as each has a different cost and listing number.
                              Had to double-check to make sure I put the right number in there, but sure enough, it's there.
                              You can see the hose coming up from #2 carb, look near the top of the hose.
                              Please note that I did say it was on the CARB FICHE.




                              I had to look at the fuel cock fiche to see what you were talking about. That is not just two views of the petcock.
                              Look carefully, you will see that the upper one is the "dreaded '80 petcock" that has no lever, the lower one is the '81 model that has a lever.
                              Judging by the picture, it also appears that the fuel hose comes out at a different angle.



                              .
                              sigpic
                              mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                              hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                              #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                              #2 son: 1980 GS1000G
                              Family Portrait
                              Siblings and Spouses
                              Mom's first ride
                              Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                              (Click on my username in the upper-left corner for e-mail info.)

                              Comment

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