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DT125R FORUM

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  4. Weak spark, or no spark

Weak spark, or no spark

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  • CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #2

    I've had this before.

    Bad grounding, lose wires and deteriorated connectors can cause this.

    Also check the HT Coil and measure its impedance and check it against the manual to see if it's within tolerance.

    Always Originate, Never Pirate!

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    1
    • Haako SmithH Offline
      Haako SmithH Offline
      Haako Smith
      wrote on last edited by
      #3

      Thanks for responding.
      I managed to get I started, but only for a couple of seconds. I felt like it was the same as yesterday. If I gave it some throttle it died. I had a random coil laying round and I checked if it was a difference, but it was the same. Sometimes weak spark.
      Should I measure the ohms in the coil?

      My bike is a Yamaha dtr 125 2002

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      • S Offline
        S Offline
        SpookDog
        wrote on last edited by
        #4

        If it’s not the coil. I’d start working through the rest of the ignition wiring and parts. Key barrel, kill switch, sidestand switch, sidestand relay (if applicable) the pulse generator/ pick up, stator coil, ect, ect...

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        1
        • CalumC Offline
          CalumC Offline
          Calum
          wrote on last edited by
          #5

          I had the ignition barrel connector block just crap out on me and that was giving me grief.

          Always Originate, Never Pirate!

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          1
          • Haako SmithH Offline
            Haako SmithH Offline
            Haako Smith
            wrote on last edited by
            #6

            Hmm. I measured the resistance between the coil, as you can see in the picture. In the manual i have, it says it shold have somewhere around 7,5K. Does my coil seem ok?![0_1597686924821_IMG_1929.jpg](Uploading 100%)

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            • Haako SmithH Offline
              Haako SmithH Offline
              Haako Smith
              wrote on last edited by
              #7

              My coil measures to 8.05K

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              • Haako SmithH Offline
                Haako SmithH Offline
                Haako Smith
                wrote on last edited by
                #8

                I tested the resistance in the pickup coil, and it showed 300 ohm. The manual says that it should have 9-11 ohm

                S 1 Reply Last reply
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                • Haako SmithH Offline
                  Haako SmithH Offline
                  Haako Smith
                  wrote on last edited by
                  #9

                  It has spark before the spark plug cap, but not after. ( sometimes it has)
                  And it’s not the cap that’s bad, I have tested it.
                  So it basically don’t have enough spark to fire.
                  So I’m thinking it’s the coil maybe??
                  Anyone else thinks so to?

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                  • O Offline
                    O Offline
                    oldman
                    wrote on last edited by
                    #10

                    My bike refused to start Sunday, tested coil (non original) and no resistance on secondary coil, swapped it for spare genuine coil expecting fix but still no spark. Checked side stand switch that was ok, checked kill switch and duff connection. Fixed that and all good. When bike was rebuilt a couple of years ago had intermittent fault where bike cut out, traced that to poor earth (corroded in loom) around coil area . Ran a new earth from there direct to battery. If you find my rebuild thread it's described in there, removed loom and tested resistance of cables and found it.

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                    • CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #11

                      It would appear as these bikes starts to age the looms are becoming susceptible to failure.

                      Always Originate, Never Pirate!

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                      • Haako SmithH Haako Smith

                        I tested the resistance in the pickup coil, and it showed 300 ohm. The manual says that it should have 9-11 ohm

                        S Offline
                        S Offline
                        SpookDog
                        wrote on last edited by
                        #12

                        @Haako-Smith said in Weak spark, or no spark:

                        I tested the resistance in the pickup coil, and it showed 300 ohm. The manual says that it should have 9-11 ohm

                        Well if that’s right then there’s way too much resistance. Resistance cuts down the amount of power flowing through.

                        I’ve got an old shitty looking one that I know works. You might have to bodge the connectors for your bike.

                        If you’re UK side you can bung me a few quid for postage and it’s yours. I wouldn’t use it full time without waterproof/mending the grommet

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                        • Haako SmithH Offline
                          Haako SmithH Offline
                          Haako Smith
                          wrote on last edited by
                          #13

                          hmm, i checked the stator aswell, and i measured that 12 volts is coming to the cdi, but only 6 volt at max is going to the coil, from the cdi. So im kinda thinking its the cdi maybe. But the resistance should not be 300 ohms at the pickup coil? Could that maybe be the cause? Im in Norway btw, so not exaclty close xD

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                          0
                          • S Offline
                            S Offline
                            SpookDog
                            wrote on last edited by
                            #14

                            Sorry, but I’m not even going to try postage to 🇳🇴. Try and find a different pick up to try. It sounds like a suspect...

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