Removing vacuum advance

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  • LoftCol
    XSive
    • Jul 2025
    • 86
    • UK

    #1

    Removing vacuum advance

    Hi,

    Has anyone removed the vacuum advance and relied upon the mechanical advance. Google tells me that it is possible, but I really want to ask those who have done it. Why? I hear some of you ask. T he carbs do not have the vacuum port on them, so I am currently using the vacuum port on the inlet rubbers, which isn't ideal.
    Thoughts/suggestions greatly appreciated.

    Thanks
  • jetmechmarty
    Master of XSology
    • Nov 2003
    • 8071
    • Coldwater, Mississippi

    #2
    Hmmm…. I think without the vacuum advance you might enjoy 25 mpg. In a word, bye bye fuel economy.

    This should eliminate the problem:
    Digital ignition system for Yamaha XS1100, replacement for the original electronic ignition and advance unit. The vacuum advance won't be used any longer. Most models have a 15 mm shaft diameter. The 2H7 and 2H9 models have a 14 mm shaft...


    Marty (in Mississippi)
    XS1100SG
    XS650SK
    XS650SH
    XS650G
    XS6502F
    XS650E

    Comment

    • LAB3
      XSive Maximus
      • May 2022
      • 822
      • Traveling the U.S. with no permanent address

      #3
      Some time back I posted a complete XJ ignition setup that gets rid of the problem with the XS ignition wires breaking. It includes the TCI box, commutator, timing plate and vacuum sensor. $150 or reasonable offer, PM me if you want to know more.
      1980 XS1100G

      Intelligent people discuss ideas, average people discuss events, petty people discuss other people.

      Comment

      • DEEBS11
        XS-XJ Guru
        • Feb 2023
        • 2030
        • Connecticut

        #4
        .....or you can keep what you have and activate the vac advance with the manifold port. However the vac signal needs to be attenuated. Some guys have mentioned using an aquarium air pump valve.



        Click image for larger version  Name:	Air pump valve.jpg Views:	0 Size:	229.9 KB ID:	891363

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        • DEEBS11
          XS-XJ Guru
          • Feb 2023
          • 2030
          • Connecticut

          #5
          .......... Click image for larger version

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          • DEEBS11
            XS-XJ Guru
            • Feb 2023
            • 2030
            • Connecticut

            #6
            Oh yea, ten bucks.

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