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  • No 2 Vac line and Dyno

    I have a pinched off vacuum line from my number 2 carb (left to right) going up to that octo thing. What effect will this have on how my bike runs? I am having issues but want to see if what you guys tell me coincides with my problem. By the way when is a Dyno not a Dyno? I have a guy who says his new Dyno reads lower than others but as he uses it for tuneups and not for HP testing he dont care. Would not all Dyno's read fairly comparably?
    2-79 XS1100 SF
    2-78 XS1100 E Best bike Ever
    80 XS 1100 SG Big bore kit but not fully running yet.
    Couple of more parts bikes of which 2 more will live!

  • #2
    That pinched off vacuum line is the one that opens the octopus. If it won't open, no fuel will flow. No fuel flow=issues. Try using the prime function on the petcock. That would be with the petcock handle pointed to the rear.
    81 SH Something Special
    81 frame, 80 tank and side covers, 79 tail light and carbs, 78 engine, 750 final drive mod, Geezer rec/reg, 140 mains, LH wheels


    79 SF MEAUQABEAUXS
    81SH Nor'eas tah (Old Red)
    80 LG Black Magic
    78 E Standard Practice


    James 3:17

    If I can make at least one person smile, or pee their pants a little, or maybe spit out their drink; then my day is not wasted.

    “Alis Volat Propriis”

    Yamaha XS 1100 Classic
    For those on FB

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    • #3
      Supposed to have the vac line from the left crank cover (timing cover) going to #2 carb.

      Vac line from octi goes to #2 carb boot.


      mro

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      • #4
        Dumb question, if the vacuum line to the Octy is going to the carb, where is your Vac. advance going. if it is to one of the boots could mean issues, timin, Idle, others. check routing (by the way, I have a special tank, no octy, no carbs when I got it, bet you can guess how I know where the vac advance goes.... have a nice day and ride safe
        I am the Lorax, I speak for the Trees

        '80 XS1100 SG (It's Evil, Wicked, Mean & Nasty)

        '79 XS1100 F R (IL Barrachino)

        '00 Suzuki Intruder 1400 (La Soccola)

        '77 KZ400s (La Putana)

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        • #5
          It might be a dumb question but I just got it back from the mechanic and it aint running worth ****. I thought it was routed wrong but was not sure so I asked. I also in the meantime have been doing searches on it to see how it should be routed etc. I also dont know how or why dyno would read different from others but he claims his reads about 30% lower than others around here.
          2-79 XS1100 SF
          2-78 XS1100 E Best bike Ever
          80 XS 1100 SG Big bore kit but not fully running yet.
          Couple of more parts bikes of which 2 more will live!

          Comment


          • #6
            A lot of people don't know this but Dynos all read different, the numbers are good if you want to compare your bike to someone else's tested on the same dyno the same day, or like he said for tunning, you run, make a change, run again and compare to see if there was an improvement. Other then that they are not worth much.

            As for the 30%, he may just be saying that because it makes people feel good to think they have more power then they do. 30% seems like a lot. Maybe his dyno isn't in the best of shape or maybe his is 15% low and the other guys are 15% high. who knows?
            1979 xs1100 Special -
            Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

            Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

            Originally posted by fredintoon
            Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
            My Bike:
            [link is broken]

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            • #7
              Checked routing and yes they were back asswards so that smoothed out a lot of issues. Now it at least revs up better and seems to be idling smoother. For some reason the gas does not run out of the carbs like it was and so on and on. Now tomorrow I can take her for a run and see if it helped with the performance issues. I have been riding for many yrs but only have now tried to do my own mechanical work. Although I am not an imbecile I am not the most mechanically knowledgable person around either. I do appreciate any and all help from you all. Thanks
              2-79 XS1100 SF
              2-78 XS1100 E Best bike Ever
              80 XS 1100 SG Big bore kit but not fully running yet.
              Couple of more parts bikes of which 2 more will live!

              Comment

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