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  • #1

    Help, Gas coming out of Airbox?

    I am new to motorcycles and have purchased a 79 XS1100 Special.

    I just purchased new carb holders because I saw gas below carbs and mine are cracked some. Today I went to move the bike, but when I went to start it, notice Gas coming out of the bottom of what I believe to be the Airbox. item that is behind the carbs. I did see that I left the fuel shut off valve in the on position and its been sitting for probably 4-5 days.

    My question : is the gas coming out of there due to the cracked carb holder boots and the fact that I left the gas on or is there something else going on as well?

    Thank you in advance.

    Steve
    79 XS1100 SF
    Tags: None
  • #2
    Float valves

    You have a float valve that is sticking open. Try tapping on the float bowls and see if it will stop. I would also check the oil and make sure you did not get gas in the crankcase.
    Dale
    78 XS1100E Standard
    Coca Cola Red
    Hooker Headers

    http://i408.photobucket.com/albums/p...m/DSC00580.jpg

    1979 XS1100 Special
    http://i408.photobucket.com/albums/p...m/DSC00612.jpg

    1980 XS Standard
    http://i408.photobucket.com/albums/p...m/DSC01137.jpg

    2006 Roadstar Warrior
    http://i408.photobucket.com/albums/p...um/warrior.jpg

    Comment

    • #3
      For some reason your float needles are not seating properly. If it was just a little gas then I am guessing there is something small holding it open or the needles just do not seat completely due to age and wear.

      It is something that needs to be fixed because gas in the oil is not a good thing!
      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

      • #4
        If it was a float valve, wouldn't that leak gas even if I am not trying to start it? I know I had this issue with a 4 wheeler and it just leaked out no matter what.

        How do I tell if there is gas in the crank case?

        Thank you

        steve
        79 XS1100 SF

        Comment

        • #5
          Check your oil level and smell it. If it's high and smells like gas, than it's diluted.
          "The Hooligan" XJ1100, Virago Gauge Pods, Screaming Eagle Mufflers, K&N Filter, hand made rear fender, side covers, and solo seat, round bar conversion, small headlight, tail light, and cat eye turn signals, chip fuses, rewired the right way.

          Pics: http://s1236.photobucket.com/user/ya...?sort=6&page=1

          Comment

          • #6
            Originally posted by unicorncomputer View Post
            My question : is the gas coming out of there due to the cracked carb holder boots ?
            Definitely no to that.

            It's a sticking float valve. Your tap was in the on position but usually they are vacuum taps which operate only when the engine is running. However, are you sure that your tap is connected up correctly and has not been bypassed at some point?

            Did you leave your bike on the sidestand? I believe it is possible for three carbs to drain into the lowest one (ie nearest the sidestand) if the float valve on that carb is not sealing properly... even if the tap is off.
            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

            • #7
              Is there some diagrams somewhere to show the proper way that they should be connected up?

              Everything has been fine for the last month and a half that I have been riding it. just noticed this today.

              Steve
              79 XS1100 SF

              Comment

              • #8
                Had this happen twice. Try a carb flush, worked for me. Turn the fuel off. Drain all four carb bowls of fuel. Leave the drain screws open and open the fuel line. Let a liter or 2 flush through the bowls. If it was a speck of rust or something it may flush out. If the float is stuck sometimes tapping works. I installed inline filters to hopefully catch future trouble.
                1100 Maxim (daily rider)

                Comment

                • #9
                  I have the same issue on my '78 E. If I leave the gas on overnight I HAVE to change the oil. I polished the needle seats and needles and have my floats set to the correct height, but if I leave the gas on all hell breaks loose.

                  The PO removed the octy and installed manual petcocks so I always try to shut the gas off as I am coming into the driveway anyway..

                  Seconding the checking of your OIL. Gas in the oil will wipe out the mains and rod bearings in little time. Dont forget to replace the oil filter too as that holds quite a bit. Also those little inline gas filters from the motorcycle place are REQUIRED.
                  Last edited by Diskman01; 08-25-2012, 09:21 PM.
                  1) Fire up Internet Explorer
                  2) http://www.yahoo.com
                  3) type "www.mapquest.com" into the Yahoo search page.
                  4) go about day as VP managing multi-million dollar financial contracts.

                  Comment

                  • #10
                    Originally posted by Diskman01 View Post
                    The PO removed the octy and installed manual petcocks so I always try to shut the gas off as I am coming into the driveway anyway..
                    '78's don't have the octy anyways

                    None of the standards do.
                    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

                    • #11
                      Both the Specials and the standards (from the factory) have vacuum operated fuel valves. On the Standard models they are built into the petcocks themselves. On Special models they have the "Octy" a separate vacuum valve. In both cases, if the engine is not running, and these valves are in place and operating correctly, then the fuel will not be able to flow to the carbs till the engine is started. This is the reason the engineers put the PRIME function into the petcocks. So you can bypass the vacuum valves to fill the bowls if they are drained or the bike sits for a long time letting the fuel evaporate out of the bowls.

                      No matter the petcock function, the float valves are what stop fuel flowing into the carbs bowls when they reach the proper fuel level. It fuel runs out the airbox or into the engine, then the float valves are not performing their given task. It may be as simple as tapping the float bowl with a screwdriver, but it may well require replacing the float needle valve depending how long since the last change out.
                      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

                      • #12
                        I think $ is why the PO replaced the original vac petcocks with the generic ones. When I got my bike it had severe water and rust in the fuel system anyway. The original petcocks were shot i'm sure.

                        Would LOVE to convert to viton needles in my carbys.. Can't seem to find the correct info on them tho. Found a thread about some that "might" work. lol
                        1) Fire up Internet Explorer
                        2) http://www.yahoo.com
                        3) type "www.mapquest.com" into the Yahoo search page.
                        4) go about day as VP managing multi-million dollar financial contracts.

                        Comment

                        • #13
                          Originally posted by Diskman01 View Post
                          Would LOVE to convert to viton needles in my carbys.. Can't seem to find the correct info on them tho. Found a thread about some that "might" work. lol
                          The viton tipped needles for the early carbs with the thread in seats come from the yamaha xv920.
                          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

                          • #14
                            SO...the 79 Special in question has two problems. First, one or more float valves are leaking. Second, the vacuum shutoff (octy, spidervalve) is leaking.

                            The first problem needs to be fixed before operating the motorcycle. Leaking carburetors will cause your bike to burn to the ground! Don't mess around. Fix it or get it fixed. There are many threads on here to help you.

                            With the inop vacuum shutoff, you have to remember to turn off your fuel taps whenever you turn the engine off. It's a safety device that does it for you when you forget. Here are instructions to rebuild it: Rebuilding the Yamaha Vacuum Fuel Valve w/pics
                            Marty (in Mississippi)
                            XS1100SG
                            XS650SK
                            XS650SH
                            XS650G
                            XS6502F
                            XS650E

                            Comment

                            • #15
                              Thank you all for this info. I am hoping to take my carbs out and change the boots tomorrow. Need to call local shop for Carb rebuild kits. Anybody know of good kits online in case they are outragous at my local shop like I am expecting to find?

                              Anyway, I hope to get the carbs out, change the carb holders, and check the oil tomorrow, will post as things go along.

                              Thank you,

                              Steve
                              79 XS1100 SF

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