Announcement

Collapse
No announcement yet.

Sudden loss of spark

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Sudden loss of spark

    My 1980 XS100SG ran great when it parked it a few weeks back. Today I went to ride and would not fire. Not spark at the plugs. Seems odd but al the plug caps seem to have open resistance...cannot get a coil reading unless i pull the caps off and probe the leads directly. Primary coils read correct. Balkst resistor voltage onky reads about 5 to 6 volts and I read on her ut shoukd read 12. New battery. Going through everything...not a clue so far.
    any ideas? Emergency Off switch? Thx.
    ps. New 5ohm caps onn order
    Past Rides:
    1969 OSSA 250 Pioneer
    1979 XS650 Special
    1978 Honda CB750K
    Current: 1980 XS1100SG

  • #2
    Broken strands inside of the insulation on the pickup coil wires are a known spark killer problem.


    ----Bax
    80 SG, --- Slightly modified with EFI.....

    Comment


    • #3
      That's next on my checklist. Thanks
      Past Rides:
      1969 OSSA 250 Pioneer
      1979 XS650 Special
      1978 Honda CB750K
      Current: 1980 XS1100SG

      Comment


      • #4
        Checking the pickup coil leads. One thing i found was the vacuim hose had split znd popped of the carb vacuum tube.
        My colors are not what my Clymers diagram shows. I am assuming the Y and W stripes are the actual pairs.
        Clymers. Actual
        R/W. R/W
        G/W. G/W
        Y. G/Y
        Y. R/Y

        i measured 730ohms between Yellows and open between the whites. Not sure how I know which coil/wire these white wires go to. Where do these wires normally get spliced to new color?

        Also the wire routes under the case right over the frame tube. Will be fun to find where I need to splice.
        Past Rides:
        1969 OSSA 250 Pioneer
        1979 XS650 Special
        1978 Honda CB750K
        Current: 1980 XS1100SG

        Comment


        • #5
          scott0757 Check out this guide.

          https://xs11.club/forum/repairs/batt...il-wire-repair

          Bax

          80 SG, --- Slightly modified with EFI.....

          Comment


          • #6
            just throwing this out there ... but it could also be your TCI. Have you checked the connections going in and out of that?
            2 - 80 LGs bought one new
            81 LH
            02 FXSTB Nighttrain
            Jim

            Comment


            • #7
              Cajun31-
              I checked all connections first, including the TCI's. I have found intermittent pickup coil leads and fixed them and am mid-rerouting that harness under the case and up behind the fuse block. Working my way thru everything. The plug wire caps seem to be a real issue...open resistance. Just strange they all went together. New cap on order. Coil primary tests perfect. Plug side tests good when caps removed. Thx for suggestion.
              Past Rides:
              1969 OSSA 250 Pioneer
              1979 XS650 Special
              1978 Honda CB750K
              Current: 1980 XS1100SG

              Comment


              • #8
                Got nice blue sparks on all 4 plugs, even those with what appeared to be open resistance plug wire caps! Go figure. Time to reassemble and test ride. Wonder if the disconnected vacuum advance line could have resulted in stressed coil wires?
                Past Rides:
                1969 OSSA 250 Pioneer
                1979 XS650 Special
                1978 Honda CB750K
                Current: 1980 XS1100SG

                Comment


                • #9
                  scott0757 The flexing pickup wires have long been an issue. Good to hear your spark has returned.

                  ---Bax

                  80 SG, --- Slightly modified with EFI.....

                  Comment


                  • #10
                    Probably too late, but this is the P/U coil wiring breakdown for a 79, may be the same as the 80...

                    https://xs11.club/forum/miscellaneou...2h7#post863762

                    2H7 (79)
                    3H3

                    Comment


                    • #11
                      Just to confirm what you provided did match my 1980 XS1100SG wiring.
                      Past Rides:
                      1969 OSSA 250 Pioneer
                      1979 XS650 Special
                      1978 Honda CB750K
                      Current: 1980 XS1100SG

                      Comment

                      Working...
                      X