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  • Carb overflow

    Has anyone come up with a vent/fix for the carb overflow prob. on the 79 carbs? I know newer carbs vent overflow to ground instead of to cyl then oil then bearings Anyone try drilling an overflow hole and vent tube setup?
    1979 XS1100 Special (Mad Max, OEM) Current
    1980 XS1100 Special
    1990 V Max
    1982 KZ750 LTD Twin
    1986 700 FZR Yamaha Fazer (faster then expected)
    1979 XS750 Special (my 1st Special)
    1974 CB750-Four



    Past/pres Car's
    1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

  • #2
    What happened to the new float needle valves you were getting...? I suppose it could be done, but after replacing my Viton tipped needles, I didn't have any reason to. The old VM carbs had brass tubes in the bowls that were higher than the proper fuel level and drained out the bottom.
    '81 XS1100 SH

    Melted to the ground during The Valley Fire

    Sep. 12th 2015

    RIP

    Comment


    • #3
      Originally posted by XS1100_OEM4ME View Post
      Has anyone come up with a vent/fix for the carb overflow prob. on the 79 carbs? I know newer carbs vent overflow to ground instead of to cyl then oil then bearings Anyone try drilling an overflow hole and vent tube setup?
      Hi OEM,
      if the carbs overflow the floats are sunk or set wrong &/or the float needles & seats ain't sealing.
      That's what needs to be fixed.
      While it's better to have the overflowing gas run out onto the street instead of finding it's way into the oil pan, it's better yet to fix the root problem.
      Fred Hill, S'toon
      XS11SG with Spirit of America sidecar
      "The Flying Pumpkin"

      Comment


      • #4
        I was not aware that 80+ carbs did anything different if they overflow. My XS400 which has the exact same carbs overflowed into the cylinders if on the center stand, and onto the ground if on the sidestand. Since my 1100's carbs have never done that to me, I don't know for sure what would happen, but if You look at how things sit, on the sidestand the carbs actually tilt slightly away from the engine, on the centerstand they are tilted towards the engine. I think this has more to do with the issue than what carbs are on the bike. Its one of the reasons I almost always park it on the sidestand, and use the centerstand only when working on it.
        Cy

        1980 XS1100G (Brutus) w/81H Engine
        Duplicolor Mirage Paint Job (Purple/Green)
        Vetter Windjammer IV
        Vetter hard bags & Trunk
        OEM Luggage Rack
        Jardine Spaghetti 4-2 exhaust system
        Spade Fuse Box
        Turn Signal Auto Cancel Mod
        750 FD Mod
        TC Spin on Oil Filter Adapter (temp removed)
        XJ1100 Front Footpegs
        XJ1100 Shocks

        I was always taught to respect my elders, but it keeps getting harder to find one.

        Comment


        • #5
          Needles

          Originally posted by 81xsproject View Post
          What happened to the new float needle valves you were getting...? I suppose it could be done, but after replacing my Viton tipped needles, I didn't have any reason to. The old VM carbs had brass tubes in the bowls that were higher than the proper fuel level and drained out the bottom.
          Back when I ask about buying better needles, most on here said not to waste the $. Last time I rebuilt carbs / octy was about two months ago and all has been fine till about a week ago when I notced a small gas stain on the starter cover I had set floats with a mic. to exact hight on both floats in each bowl to spec and had tested for any leaks and all was OK. I am not currently (but will be soon) running inline filters. My guess is a pice os S#!T got into one of the needles valves, which would cause a leak regardless of the type of needles I use I know when "all" is working correctly, no problem but just burining up the bearings once is. Some of my other bikes vented gas through a hose to avoid the one time
          1979 XS1100 Special (Mad Max, OEM) Current
          1980 XS1100 Special
          1990 V Max
          1982 KZ750 LTD Twin
          1986 700 FZR Yamaha Fazer (faster then expected)
          1979 XS750 Special (my 1st Special)
          1974 CB750-Four



          Past/pres Car's
          1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

          Comment


          • #6
            I think whether the gas goes into the cylinders or into the airbox depends entirely on how the carbs sit as far as orientation on the bike. If they slant away from the engine, then any gas that overflows will flow away from the engine into the airbox and onto the ground, if they tilt towards the engine, the the gas will flow into the head, pooling on the intake valves if they are closed, or into the cylinder if they are open. Of course if it gets into the cylinders it's gonna seep past the rings into the oil.

            That's why I park on the sidestand, if it's sitting like that, or being ridden, it will pi$$ all over the ground (this assumes level ground of course), but on the centerstand the rear is is raised enough to tilt them toward the front of the bike rather than the slight tilt to the rear they normally have (unless your stopping). Even better, my garage slops slightly towards the door, making them tilt even more toward the back of the bike.
            Cy

            1980 XS1100G (Brutus) w/81H Engine
            Duplicolor Mirage Paint Job (Purple/Green)
            Vetter Windjammer IV
            Vetter hard bags & Trunk
            OEM Luggage Rack
            Jardine Spaghetti 4-2 exhaust system
            Spade Fuse Box
            Turn Signal Auto Cancel Mod
            750 FD Mod
            TC Spin on Oil Filter Adapter (temp removed)
            XJ1100 Front Footpegs
            XJ1100 Shocks

            I was always taught to respect my elders, but it keeps getting harder to find one.

            Comment


            • #7
              Uhm... when you did the carbs, you DID put in new STOCK needles, yes?
              "Damn it Jim, I'm a doctor, not a mechanic!' ('Bones' McCoy)

              Comment


              • #8
                Kits

                Originally posted by prometheus578 View Post
                Uhm... when you did the carbs, you DID put in new STOCK needles, yes?
                Yes, I installed 4 new complet K&L carb kits to the tune of about $100,00
                1979 XS1100 Special (Mad Max, OEM) Current
                1980 XS1100 Special
                1990 V Max
                1982 KZ750 LTD Twin
                1986 700 FZR Yamaha Fazer (faster then expected)
                1979 XS750 Special (my 1st Special)
                1974 CB750-Four



                Past/pres Car's
                1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                Comment


                • #9
                  Most likely you just got a piece of dirt up in there that stuck a float open. You can try adding soem sea foam to the gas, and or, just ride it a bit and then park it and see what you see. But I would be sure to turn the petcocks off every time you park it.
                  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


                  • #10
                    JAT, sometimes after being compressed, the bowl gaskets will hit the bulbs of the brass floats, causing them to hang up. On some kits, they tend to be a bit larger. When rebuilding these carbs, I usually either trim the gaskets down a bit and/or slightly bend the float bulbs in towards the center to prevent any contact between the two. In line fuel filters are a very good idea.
                    2H7 (79) owned since '89
                    3H3 owned since '06

                    "If it ain't broke, modify it"

                    Comment


                    • #11
                      Carb's

                      Originally posted by bikerphil View Post
                      JAT, sometimes after being compressed, the bowl gaskets will hit the bulbs of the brass floats, causing them to hang up. On some kits, they tend to be a bit larger. When rebuilding these carbs, I usually either trim the gaskets down a bit and/or slightly bend the float bulbs in towards the center to prevent any contact between the two. In line fuel filters are a very good idea.
                      Thanks Phil, I will def be installing in line filters and re-check gaskets as i will be R/I carbs again I am picky, ANY leak drives me nuts. I was checking out your bike pic's again, NICE. You are picky too
                      1979 XS1100 Special (Mad Max, OEM) Current
                      1980 XS1100 Special
                      1990 V Max
                      1982 KZ750 LTD Twin
                      1986 700 FZR Yamaha Fazer (faster then expected)
                      1979 XS750 Special (my 1st Special)
                      1974 CB750-Four



                      Past/pres Car's
                      1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                      Comment


                      • #12
                        Check your floats to make sure none have fuel inside them. Your piece of crud scenario could be the case, but then again, there is a reason I went so far out of my way to find a way to get Viton tipped needle into 70's carbs. I know it goes against everything you stand for, but stock isn't always best. (although with these bike it is MOST of the time).
                        '81 XS1100 SH

                        Melted to the ground during The Valley Fire

                        Sep. 12th 2015

                        RIP

                        Comment


                        • #13
                          No

                          Originally posted by 81xsproject View Post
                          Check your floats to make sure none have fuel inside them. Your piece of crud scenario could be the case, but then again, there is a reason I went so far out of my way to find a way to get Viton tipped needle into 70's carbs. I know it goes against everything you stand for, but stock isn't always best. (although with these bike it is MOST of the time).
                          No, not against what I stand for, I am all about "upgrades" just beleive that "most changes" are not "upgrades" ie, exaust, intake and others. I do feel that a change from metal needles could be a good thing as anything that keeps gas out of my crankcase is a good thing If you have had that good of results with the new needles, please send me a link to the right ones for a 79 special where i can buy and I probably will, I respect your opinion
                          1979 XS1100 Special (Mad Max, OEM) Current
                          1980 XS1100 Special
                          1990 V Max
                          1982 KZ750 LTD Twin
                          1986 700 FZR Yamaha Fazer (faster then expected)
                          1979 XS750 Special (my 1st Special)
                          1974 CB750-Four



                          Past/pres Car's
                          1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                          Comment


                          • #14
                            Originally posted by XS1100_OEM4ME View Post
                            Thanks Phil, I will def be installing in line filters and re-check gaskets as i will be R/I carbs again I am picky, ANY leak drives me nuts. I was checking out your bike pic's again, NICE. You are picky too
                            Yep, NP. Stay away from these filters as they are NFG...

                            http://www.xs11.com/forum/showthread...ning+defective
                            2H7 (79) owned since '89
                            3H3 owned since '06

                            "If it ain't broke, modify it"

                            Comment


                            • #15
                              filters

                              Originally posted by bikerphil View Post
                              Yep, NP. Stay away from these filters as they are NFG...

                              http://www.xs11.com/forum/showthread...ning+defective
                              Do you have an inline filter you would recomend
                              1979 XS1100 Special (Mad Max, OEM) Current
                              1980 XS1100 Special
                              1990 V Max
                              1982 KZ750 LTD Twin
                              1986 700 FZR Yamaha Fazer (faster then expected)
                              1979 XS750 Special (my 1st Special)
                              1974 CB750-Four



                              Past/pres Car's
                              1961 Catalina 389/1970 Torino GT 351/1967GTO 12to1 comp./ Roller cam/ T-10/ 456 gear/Tri-power/1967 GTO 400, 1969 Camaro, 1968 Z28, 2001 BMW M Roadster 0 to 60 in 4.5 sec. Jaguar XK8

                              Comment

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