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DT125R FORUM

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Head scratcher

Scheduled Pinned Locked Moved Engine
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  • StanKnS Offline
    StanKnS Offline
    StanKn
    wrote on last edited by
    #13

    I've rebuilt the top end, checked the ring gap all perfect new gudgeon pin and bearing too, it's running a brand new genuine yamaha coil right now. Is their any way of checking for a break with multimeter all the wires. Spark is perfect, but plug always comes out a little oily and black

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    • StanKnS Offline
      StanKnS Offline
      StanKn
      wrote on last edited by
      #14

      *all the wires seem okay on a visual inspection

      S 1 Reply Last reply
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      • StanKnS StanKn

        *all the wires seem okay on a visual inspection

        S Offline
        S Offline
        SpookDog
        wrote on last edited by
        #15

        @StanKn

        Oily and black is rich mixture. Probably where you’ve played with the needle/carb settings…

        You won’t see a break inside the insulation.
        I don’t know much about your model but it sounds like it’s rev limiting itself. If the wire (green?) isn’t properly earthed, or connected to it’s proper place (CDI?) the CDI might be defaulting to a ‘safe’ mode. I’ve heard of similar problems with bikes with the rev limiter read bulb in the speedometer…

        It’s the only thing I can think of if everything else is in good order like you said. It started off intermittent then failed completely…

        You can do continuity testing with a multimeter. You may have to pierce the wire with a pin to make a testing point…

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        • StanKnS Offline
          StanKnS Offline
          StanKn
          wrote on last edited by
          #16

          Interesting, I've got it running leaner now and it's a a fraction better but still doesnt rev under load.
          What do you mean by rev limiter read bulbs? I'll do a bit more Inspecting today.
          Thanks for all the help. It's greatly appreciated.

          S 1 Reply Last reply
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          • StanKnS StanKn

            Interesting, I've got it running leaner now and it's a a fraction better but still doesnt rev under load.
            What do you mean by rev limiter read bulbs? I'll do a bit more Inspecting today.
            Thanks for all the help. It's greatly appreciated.

            S Offline
            S Offline
            SpookDog
            wrote on last edited by SpookDog
            #17

            @StanKn

            Hey! Try running it with the ‘deristrict’ wire not earthed. See if there’s any difference…

            The reed/read bulb refers to a dtr (don’t know what year) rev limiter…

            PS have you cleaned out the jets and emulsion tube when you had the carb apart?…

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            • StanKnS Offline
              StanKnS Offline
              StanKn
              wrote on last edited by
              #18

              I've cleaned all the jets, but was wondering the emulsion tube refers to the press put large jet, that the main jet screws into, does that have some small holes going up the sides, I've only ever sprayed it with compressed air I've never removed it perhaps they may be blocked if they are present. I reconnected the wire yesterday and it made zero difference, I'll have a look to see if I have that read bulb. Thanks again @SpookDog

              HOTSHOT IIIH 1 Reply Last reply
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              • StanKnS Offline
                StanKnS Offline
                StanKn
                wrote on last edited by
                #19

                If it helps @SpookDog my CDI is marked 5AN 72P

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                • StanKnS Offline
                  StanKnS Offline
                  StanKn
                  wrote on last edited by
                  #20

                  Hope this image works, just found this could be an issue?
                  link text

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                  • StanKnS StanKn

                    I've cleaned all the jets, but was wondering the emulsion tube refers to the press put large jet, that the main jet screws into, does that have some small holes going up the sides, I've only ever sprayed it with compressed air I've never removed it perhaps they may be blocked if they are present. I reconnected the wire yesterday and it made zero difference, I'll have a look to see if I have that read bulb. Thanks again @SpookDog

                    HOTSHOT IIIH Offline
                    HOTSHOT IIIH Offline
                    HOTSHOT III
                    wrote on last edited by
                    #21

                    @StanKn The emulsion tube is the long brass tube the main jet screws into yes. If you haven't done this yet you'll need to get this out (screw the main jet back in without the brass washer and lightly tap it), make sure all the holes in the tube are unblocked and also check its air feed is clear, this is the small clear tube which pushes onto a brass tube on the right of the carb body just in front of the carb-to-airbox rubber (it's a very small hole and difficult to blow through).

                    What happens over time is the space between the carb body and emulsion tube accumulates moisture and debris and this blocks more and more of the holes until it just starts fourstroking one day.

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                    • StanKnS Offline
                      StanKnS Offline
                      StanKn
                      wrote on last edited by
                      #22

                      Christ, I thought it was just a big brass tube since there was no easy looking way to get it out. Feel a bit silly now ahah.

                      S 1 Reply Last reply
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                      • StanKnS StanKn

                        Christ, I thought it was just a big brass tube since there was no easy looking way to get it out. Feel a bit silly now ahah.

                        S Offline
                        S Offline
                        SpookDog
                        wrote on last edited by
                        #23

                        CDI doesn’t look right. I’ve never seen one with blue shrink insulation…

                        CalumC 1 Reply Last reply
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                        • S SpookDog

                          CDI doesn’t look right. I’ve never seen one with blue shrink insulation…

                          CalumC Offline
                          CalumC Offline
                          Calum
                          wrote on last edited by
                          #24

                          @SpookDog I wouldn't get excited about the shrink wrap, it's not a DTR after all.

                          https://motorradteilehannover.de/Yamaha-TDR-125-5AN-Bj-1997-control-unit-CDI-control-part-A3999

                          Does look very similar to a DTRE ignition system though. Zeeltronic might be a good upgrade to the TDR ignition system.

                          Always Originate, Never Pirate!

                          S 1 Reply Last reply
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                          • StanKnS Offline
                            StanKnS Offline
                            StanKn
                            wrote on last edited by
                            #25

                            Thanks again lads. Yeah I'm definitely going to get the zeeltronic in the future maybe this a sign to get it now

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                            • CalumC Calum

                              @SpookDog I wouldn't get excited about the shrink wrap, it's not a DTR after all.

                              https://motorradteilehannover.de/Yamaha-TDR-125-5AN-Bj-1997-control-unit-CDI-control-part-A3999

                              Does look very similar to a DTRE ignition system though. Zeeltronic might be a good upgrade to the TDR ignition system.

                              S Offline
                              S Offline
                              SpookDog
                              wrote on last edited by SpookDog
                              #26

                              Wasn’t just the wrap. It was the gap in the resin around the wires. But yeah, I have no experience with later bikes 🙂 RE was a boring class I had to sit through when I was 10 years old…

                              I hope you find the problem…

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                              • StanKnS Offline
                                StanKnS Offline
                                StanKn
                                wrote on last edited by
                                #27

                                Thanks for all the input and advice. I'll try it all 🤣. I hope so too @SpookDog. Thanks for all the help again really appreciate it

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                                • StanKnS Offline
                                  StanKnS Offline
                                  StanKn
                                  wrote on last edited by
                                  #28

                                  @HOTSHOT-III thanks mate you were write , feel like such an arse currently there's was around 10 years of crud in the emulsion tube. I overthinked like mad feels a bit silly hahaha. She's is running a real treat took awhile to get the tube out not sure its even been out before

                                  HOTSHOT IIIH S 2 Replies Last reply
                                  1
                                  • StanKnS StanKn

                                    @HOTSHOT-III thanks mate you were write , feel like such an arse currently there's was around 10 years of crud in the emulsion tube. I overthinked like mad feels a bit silly hahaha. She's is running a real treat took awhile to get the tube out not sure its even been out before

                                    HOTSHOT IIIH Offline
                                    HOTSHOT IIIH Offline
                                    HOTSHOT III
                                    wrote on last edited by
                                    #29

                                    @StanKn No worries bud, lots of people miss this the 1st time they do a carb strip on these bikes. Glad to hear it's running better now!

                                    1 Reply Last reply
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                                    • StanKnS StanKn

                                      @HOTSHOT-III thanks mate you were write , feel like such an arse currently there's was around 10 years of crud in the emulsion tube. I overthinked like mad feels a bit silly hahaha. She's is running a real treat took awhile to get the tube out not sure its even been out before

                                      S Offline
                                      S Offline
                                      SpookDog
                                      wrote on last edited by
                                      #30

                                      @StanKn

                                      Mine was like it when I first sussed out it was removable. It was caked in what looked like cement dust!
                                      I’m glad you got it running sweet again 😜

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