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1980 gs550e - fuel tap / tank noise

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    #16
    what carbs have you got, BS or VM, your first post you say vac pipe is on #3 carb and now you say its on #2 carb, so which is it?
    1978 GS1085.

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

    Comment


      #17
      Petcock vacuum goes to carb 2
      Bs carbs

      (I won't be near bike till later today )

      I'll do some tests later and strip the
      petcock. ( I'll also re for my one I had to use on long trip
      in an emergency as can't remember if that too had the noise issue )

      But for years it has done this .
      But the diaphragm in the petcock must
      open / close almost every second.


      Note:
      The bike runs like a dream. Tuned spot on.
      Does not have a fuel filter (no room or it would)
      Totally standard bike.
      Last edited by ukjules; 06-26-2017, 02:35 AM.
      UKJULES
      ---------------------------------
      Owner of following bikes:
      1980 Suzuki GS550ET
      1977 Yamaha RD 250D
      1982 Kawasaki GPZ 750 R1
      1980 Suzuki GSX 250E

      Comment


        #18
        No, when there is vacuum then the valve opens, when there is no vacuum the valve closes, ie one cycle per engine on and engine off.

        Have you tried opening the fuel cap to see if the clanking goes away?
        Last edited by tatu; 06-26-2017, 02:55 AM.
        sigpic

        Don't say can't, as anything is possible with time and effort, but, if you don't have time things get tougher and require more effort.

        Comment


          #19
          I will redo tests later this afternoon!

          I have taken the fuel cap off a d clanking remains.
          Let me check again ...

          Re the petcock from z1 enterprises.
          It looks to fit as they have emailed. Same dimensions as mine
          I'll check prices etc and might try it .

          Tests:
          -Good sealing vacuum pipe
          -Fuel cap off , running along
          -Vacuum pipe off but blocked off tank end ?

          Any other analysis I can do this eve .
          I can also strip it and check internals.
          UKJULES
          ---------------------------------
          Owner of following bikes:
          1980 Suzuki GS550ET
          1977 Yamaha RD 250D
          1982 Kawasaki GPZ 750 R1
          1980 Suzuki GSX 250E

          Comment


            #20
            Bare with - I have some success but using another
            fuel tap.

            I'll update later with pics but my internals
            on the petcock were broke again , the metal bit on the diaphragm

            pic is original petcockgs550e standard petcock - no prime.jpg
            Last edited by ukjules; 06-26-2017, 03:40 PM.
            UKJULES
            ---------------------------------
            Owner of following bikes:
            1980 Suzuki GS550ET
            1977 Yamaha RD 250D
            1982 Kawasaki GPZ 750 R1
            1980 Suzuki GSX 250E

            Comment


              #21
              Update:

              status as was: I am sure this was the original petcock, it might have always done this.
              It was clanking along with the pulses from the vacuum tube.
              Clanking as the diaphragm for some reason was doing this:

              Analysis:
              -Riding along with fuel cap off - no change
              -engine running on and res position – no change
              -it always seemed to be bad when nearing reserve. However when I pushed it into running out on reserve and the clanking pronounced it has been a lot worse.
              -Engine running – static – pull vacuum pipe of tank – clanking stops .
              the pulses from the vacuum can be felt sucking in (1 a second)
              -tried a tighter fit vacuum pipe –no change

              Stripped petcock:
              As you can see from the picture – the diaphragm metal disk has split in two.
              -So we can say that this was the issue. BUT I renewed this from a petcock kit a while ago. (I am afraid I cannot remember the result and if it solved it for a while)
              So I must assume it rattles when the diaphragm metal washer is broken only.
              And that it broke as was a cheap petcock kit ?

              Not good analysis BUT read on:

              I have a GSX250e 1980. the fuel tap has res/on and a prime screw.
              Fortunately it has 50mm outside to outside bolt holes and m6 bolts.
              the internals are also the same diaphragm as the original gs550e petcock.

              GSX250e one on and it works fine – no clanking.

              Q) If you remove the vacuum pipe you will feel the pulsing ?
              (When you put it back on a working fuel tap it sucks in and remains open )
              gs550e standard petcock - internals - disc broken - tapping pulse.jpg
              Last edited by ukjules; 06-26-2017, 07:17 PM.
              UKJULES
              ---------------------------------
              Owner of following bikes:
              1980 Suzuki GS550ET
              1977 Yamaha RD 250D
              1982 Kawasaki GPZ 750 R1
              1980 Suzuki GSX 250E

              Comment


                #22
                My bike with the gsx250e 1980 petcock.

                It works fine (for the last 3 miles)
                and has the reserve screw !! so needed when the bike is left for a while !!!

                m6 screws
                50-50mm outside to outside holes
                gsx250e 1980 petcock on a gs550e 1980- fits and works - has prime screw.jpg
                UKJULES
                ---------------------------------
                Owner of following bikes:
                1980 Suzuki GS550ET
                1977 Yamaha RD 250D
                1982 Kawasaki GPZ 750 R1
                1980 Suzuki GSX 250E

                Comment


                  #23
                  Update:

                  I am convinced I have heard the tapping again using another
                  petcock. The gsx250 one I used. It's slight but it's there.
                  I am flummoxed !

                  I will not stop until I get to the bottom of this.

                  : I have ordered a petcock kit and will
                  put that in my original one ( the one with just
                  On and Res).
                  I will then test like that and we must assume it will
                  be fine.( For a while at least )

                  : When I do that I'll strip the one in now ( the gsx250
                  one , that seems to have started tapping
                  ( We would expect here the petcock diaphragm beginning to break )

                  Notes:
                  The gsx one is old and the internals were 20 plus
                  years old and diaphragm might be old , inflexible )

                  I am assuming the above as it simply cannot
                  be the vacuum ruining the diaphragms in the petcock ?

                  I use good quality fuel only !!!

                  I'll report when I do the above and then
                  put down full analysis.

                  But I'd someone has a gs550et 1980 this has to have happened
                  before ?
                  Last edited by ukjules; 07-03-2017, 02:04 PM.
                  UKJULES
                  ---------------------------------
                  Owner of following bikes:
                  1980 Suzuki GS550ET
                  1977 Yamaha RD 250D
                  1982 Kawasaki GPZ 750 R1
                  1980 Suzuki GSX 250E

                  Comment


                    #24
                    Update:
                    A 200 mile camping trip and bike was fine.
                    Using the gsx250e 1980 tap with prime.
                    It works a treat but I am sure I hear tapping but only when 3/4 full.
                    Madness.

                    Whatever it works . Might help others with these petcock locating issues.

                    When the repair kit arrives I'll inspect .
                    UKJULES
                    ---------------------------------
                    Owner of following bikes:
                    1980 Suzuki GS550ET
                    1977 Yamaha RD 250D
                    1982 Kawasaki GPZ 750 R1
                    1980 Suzuki GSX 250E

                    Comment


                      #25
                      Ukjules, I have the same problem and the same petcock as your original.

                      I started out chasing a tapping noise that I thought was originating from the valve train, but turned out to be the petcock. Before I heard the wisdom of the sages I had already ordered a rebuild kit for my 1980 gs550e. Kit arrived...diaphragm wasn't even close to what I needed. Ordered a whole new OEM petcock from local shop for my 1980 gs550e. Part arrived....not even close to the petcock I just took off my tank. I'm not sure what year my tank is.

                      Tomorrow when I get to a real keyboard i'm going to start a new thread with more details and some pics. Our mysteries have a lot in common.

                      Comment


                        #26
                        I haven't had this but trying to think what this could be! Yes it'll be rythmic to the valves of course if it is the vacuum function creating it ...Stil,l disconnecting AND PLUGGING the vacuum line when on prime should confirm it is the vacuum of engine.

                        hmm. Any chance the spring against the diaphragm is on the wrong side? (it holds the piston and its oring to close fuel...)

                        I was also thinking it's possible that the vacuum piston is tapping on the doodad circular bit that holds piston from sealing when turned to prime but not in ukjules case because he has the ol'style prime screw...

                        Comment


                          #27
                          I bought a petcock at the scrapyard today...and tore it down to fix it. I figure it dates from 1983 -1985? when we were getting 450 T's in Canada
                          IT
                          reminded me of this thread....it may have an answer why some make tapping noises: its diaghragm has two layers of thin "rubber" that sheath a thin round disc inside them..this disc pops in and out like the old oilcans (if you know the ones I mean- if not maybe squeezing a beer can will duplicate it)
                          Anyways, it makes a definite noise as it "pops" when vacuum is applied... to pull the plunger back from the fuel passage..In fact, when vacuum is not happening, the petcock stays open awhile before popping back to the original closed state. This might be its purpose... but I can get it to make quite a racket sucking and blowing on the vacuum line . If there were sufficient backpressure on every pulse of the valves, then I can see this being a cause...

                          It is a design of diaphragm I've never seen before-never seen one with this internal metal (or is it plastic? ) If one of you have this you'd know it -it's stiff except on it's edge that is under the metal petcock assembly. Everything else is the same as my other petcocks, including the thin metal backing disc on the outside of the diaphragm...

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