Announcement

Collapse
No announcement yet.

Fuel tank breather

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
  • #1

    Fuel tank breather

    Hi Folks. Can you someone please explain to me how the fuel tank breather works? I've noticed that often, there is a whistly sound coming from my fuel tank cap when I park up. Sometimes, it's still doing this 10 minutes later and I'm wondering if the breather hole (wherever it is) is partially blocked. The noise stops if I undo the tank filler cap.

    How does the cap allow air into the tank as the fuel is used up and has anyone else had this whistling sound? How does one clean it?
    XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.
    Tags: None
  • #2
    I think that you are referring to the vent in the gas cap itself.There should be a small hole in the center of the cap to allow the tank to vent.You can try to take a small piece of wire to clear it out if it is plugged-but i think that you would have other issues besides a whistling sound.I believe if the hole is plugged you might have a fuel flow issue.
    1980 XS1100 SG
    Inline fuel filters
    New wires in old coils-outer spark plugs
    160 mph speedometer mod
    Kerker Exhaust
    xschop K & N air filter setup
    Dynojet Recalibration kit
    1999 Kawasaki ZRX1100
    1997 Jeep Cherokee 4.5"lift installed

    Comment

    • #3
      If you take the 3 screws out of the bottom of the cap and seperate it from the rubber gasket, you will see a fiber disk in there that has a tiny vent hole in it. Enlarge that hole with an awl a bit, clean everything up and reassemble. Best bet is to remove the entire gas cap and set it on the bench to service it.
      2H7 (79) owned since '89
      3H3 owned since '06

      "If it ain't broke, modify it"

      ☮

      Comment

      • #4
        Yes, I'm thinking that I do have a slight fuel flow issue, actually. I'm getting a slight fuel starvation occasionally and, when it happens and I turn off the engine, there's the whistly sound. I think the vent is partially blocked. I'll proggle about with a bit of wire in the hole in the middle of the cap then.......
        XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.

        Comment

        • #5
          Thanks for the help
          XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.

          Comment

          • #6
            On mine there is the hole pointing down into the tank, the when moving out from that hole there is a small brass disc with a hole in the center, then there is the fiber disc with a hole that is off to the side and then it is open to the atmospheric air.
            Nathan
            KD9ARL

            μολὼν λαβέ

            1978 XS1100E
            K&N Filter
            #45 pilot Jet, #137.5 Main Jet
            OEM Exhaust
            ATK Fork Brace
            LED Dash lights
            Ammeter, Oil Pressure, Oil Temp, and Volt Meters
            Green Monster Coils
            SS Brake Lines
            Vision 550 Auto Tensioner

            In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

            Theodore Roosevelt

            Comment

            • #7
              Job now done. The pinhole in the centre of the fuel cap was almost fully blocked by a piece of flaked off fuel deposit.

              I removed the entire fuel flap from the tank and removed the innards by removing the lock assembly (2 small screws). This let the plate which holds the cap out of the flap and, behind it is a circlip. I removed this and the fuel cap came completely out with a spring behind it (that pushes the rubber seal onto the lip of the tank). I undid the three small screws and took the back off. There's a gasket with a pinhole in it and under that the brass washer (with hole) and a piece of foam.

              The problem was a bit of deposit which had dropped into the hole at the bottom of the cap... the bit that gets the fuel sloshing over it. It's the stuff you get inside dirty carbs. Some of this deposit had formed in the hole and finally almost blocked it. I could hardly blow through it. Also the fibre gasket had got mushy in the middle and the little hole was blocked. I removed some of the gasket around the hole

              Now nice and clean and letting air through correctly!

              Thanks fellas
              XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.

              Comment

              • #8
                Originally posted by James England View Post
                The problem was a bit of deposit which had dropped into the hole at the bottom of the cap...
                Yup, that's one more spooge hole to watch for...
                Ken Talbot

                Comment

                • #9
                  Originally posted by Ken Talbot View Post
                  Yup, that's one more spooge hole to watch for...
                  It def is. The fuel sloshes up into the hole in the cap and, I presume, after a number of years, forms a deposit. Mine took a lot of poking to get out too. Went out today and no whistling from the cap and, better, not a hint of fuel problems. Looking at the state of my cap, it really should be the first port of call on any fuel/carb issues....
                  XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.

                  Comment

                  • #10
                    James, HERE is some more info on the gas cap, seal, and vent.
                    Life is what happens while your planning everything else!

                    When your work speaks for itself, don't interrupt.

                    81 XS1100 Special - Humpty Dumpty
                    80 XS1100 Special - Project Resurrection


                    Previously owned
                    93 GSX600F
                    80 XS1100 Special - Ruby
                    81 XS1100 Special
                    81 CB750 C
                    80 CB750 C
                    78 XS750

                    Comment

                    • #11
                      Originally posted by DGXSER View Post
                      James, HERE is some more info on the gas cap, seal, and vent.
                      Yep... that's what I did to mine and was amazed at all the deposits and gunge in there. Now good for another 30 years? Great, I'll mark it in the diary to do again when I'm 82 years old.
                      XS1100F 1980 European model. Standard. Dyna coils. Iridium plugs. XS750 final drive (sometimes). Micron fork brace. Progressive front springs. Geezer regulator/rectifier. Stainless 4 into 2 exhaust. Auto CCT (Venturer 1300) SOLD. New project now on the go. 1980 European model.

                      Comment

                      Previous template Next
                      Working...
                      X