Resistance is futile...

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  • dbeardslee
    XS-XJ Super Guru
    • Nov 2007
    • 4385
    • Maineville, OH

    #1

    Resistance is futile...

    So I was tracking down a gremlin last night, and I found something that gave me a cause for a pause. When I check the resistance to the coils at the TCI connection, I get a reading of 2.8 ohms. I've got the old style Mikes XS coils, which are supposed to be 3 ohm coils, so I don't know why I'm getting a lower reading. Is that too low for our TCI's, or is it in an acceptable range? I found the problem I was looking for (pickup coil wires), and the coils aren't giving me any trouble - I'm just concerned about the TCI and whether or not 2.8 ohms will do damage.
    I think I have a loose screw behind the handlebars.

    '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines
  • rpgoerlich
    XSive Maximus
    • Dec 2007
    • 643
    • Katy, Tx

    #2
    When you put the test leads together do you get Zero?
    Richard

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    • dbeardslee
      XS-XJ Super Guru
      • Nov 2007
      • 4385
      • Maineville, OH

      #3
      When you put the test leads together do you get Zero?
      On what? If you're asking me if my multimeter works, it does.
      I think I have a loose screw behind the handlebars.

      '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines

      Comment

      • Ivan
        XS-XJ Guru
        • Jul 2008
        • 2524
        • Hutchinson KS

        #4
        Ohm meters are actually a voltmeter that measures voltage across a shunt. On quality DMMs, you can pull them apart and see the aluminum wire with a little scallop ground in it. They are highly inaccurate, and if you are seeing 2.8 ohms, I wouldn't worry about it. Next week with the same emter on the same wires you'll see 3.5

        The only true way to get accurate ohms readings is on a loaded circuit using voltage and amperage to calculate it out.
        Ich habe dich nicht gefragt.

        Comment

        • dbeardslee
          XS-XJ Super Guru
          • Nov 2007
          • 4385
          • Maineville, OH

          #5
          It just hit me what RP was asking. It's a digital multimeter that zeros itself, and yes if you put the leads together it's properly calibrated. I'll look at it again and see if I get different readings in a week or so. Just don't want to fry a TCI. I'd still like to know if 2.8 ohms can cause damage, or is that within an acceptable service limit? Who knows, I may have actually gotten a valid reading - even a broken clock is right twice a day .
          I think I have a loose screw behind the handlebars.

          '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines

          Comment

          • TopCatGr58
            Administrator
            • Jul 2002
            • 12650
            • Portsmouth, Va.

            #6
            Hey DB,

            IIRC I got about the same reading on my DVM, but I think I also saw the same or similar value from my OEM's that were still working at the time I removed/replaced them with the MikesXS ones. I have ridden an LDR trip from here to Pa, and back, etc. No problems, I'm pretty sure that the 2.8 ohms is enough load/resistance for the TCI. It's only when you try to run those CDI type coils at 0.7 ohms that the TCI frying is guaranteed.
            T.C.
            T. C. Gresham
            81SH "Godzilla" . . .1179cc super-rat.
            79SF "The Teacher" . . .basket case!
            History shows again and again,
            How nature points out the folly of men!

            Comment

            • dbeardslee
              XS-XJ Super Guru
              • Nov 2007
              • 4385
              • Maineville, OH

              #7
              Thanks, TC. That's what I was looking for.
              I think I have a loose screw behind the handlebars.

              '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines

              Comment

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