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DT125R FORUM

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  4. Reading the Spark Plug Color

Reading the Spark Plug Color

Scheduled Pinned Locked Moved Engine
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  • P panmil92

    @NINJA I lost you there.., i don't see something in this thread ( this is my first thread on this site , so i may miss something ).

    CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #8

    @panmil92 Did you have the cylinder honed? Its not enough to simply through in a setof rings a d a piston on a used bore. The piston rings need to seal on the cylinder walls.

    Whilst I doubt thats your problem its worth checking.

    Are you getting excessive smoke? That plug looks too oily. I winder if the cranjkshaft seal is starting to weep.

    Always Originate, Never Pirate!

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    • P panmil92

      @NINJA I lost you there.., i don't see something in this thread ( this is my first thread on this site , so i may miss something ).

      NINJAN Offline
      NINJAN Offline
      NINJA
      wrote on last edited by NINJA
      #9

      @panmil92 WHOOPS!!! My bad I forgot to add the link. :grinning_face_with_smiling_eyes: :pouting_face: :confounded_face: :persevering_face: :smiling_face_with_open_mouth_closed_eyes: :winking_face:

      See here; https://dt125r.co.uk/topic/1590/spark-plug-heat-range-advice

      SEDUCED BY THE DARK SIDE!!!

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      • CalumC Calum

        @panmil92 Did you have the cylinder honed? Its not enough to simply through in a setof rings a d a piston on a used bore. The piston rings need to seal on the cylinder walls.

        Whilst I doubt thats your problem its worth checking.

        Are you getting excessive smoke? That plug looks too oily. I winder if the cranjkshaft seal is starting to weep.

        P Offline
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        panmil92
        wrote on last edited by panmil92
        #10

        @Calum I took the cylinder to a well known shop for doing honing/ reboring , etc ( in Greece ) , he actually checked the cylinder for clearances as well as condition ( for almost 40 mins ) and then he gave me the correct piston. So I guess ( hope ) that honing is not the issue. I wouldn’t say I get excessive smoke. It smokes in the beginning and under hard acceleration , no more than what I see on youtube with this bike..

        About the crank seals I have no idea, I check the oil level when warm and it seems the same. Unfortunately with the university, the only period of the year I can do the bottom end is the next summer. ( I’ll probably do it anyway then cause the old one had a little surface rust on the counterweights and I want to replace the bearing as well , i just hope it doesn't give up in this year :smiling_face_with_halo: )

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        • NINJAN NINJA

          @panmil92 WHOOPS!!! My bad I forgot to add the link. :grinning_face_with_smiling_eyes: :pouting_face: :confounded_face: :persevering_face: :smiling_face_with_open_mouth_closed_eyes: :winking_face:

          See here; https://dt125r.co.uk/topic/1590/spark-plug-heat-range-advice

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          panmil92
          wrote on last edited by
          #11

          @NINJA Thanks ! No worries ,I actually visited that thread when I was browsing the site 😛

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          • P Offline
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            panmil92
            wrote on last edited by panmil92
            #12

            QUESTION : Will a dead battery affect the performance of the bike at WOT ? .

            On my way driving home, I noticed my horn was not working ( when a real gentleman driving an Audi decided to cut in my lane , as I was accelerating, with no flash/warning :face_with_steam_from_nose: ) and after I arrived home I checked the battery to find a dead cell. The max voltage of the battery under 0.5 Amp load was a steady 10,3v. No load voltage of 12.6v.

            In the same day , before I noticed the battery issue, I replaced the main jet to the manual recommended 240 ( from the 190 I was running as a test) and the bike starts to bog the moment you pass the ¾ of the throttle.

            So, will the dead battery make my bike feel over-rich as I go WOT or the two things are not connected ?

            CalumC 1 Reply Last reply
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            • P panmil92

              QUESTION : Will a dead battery affect the performance of the bike at WOT ? .

              On my way driving home, I noticed my horn was not working ( when a real gentleman driving an Audi decided to cut in my lane , as I was accelerating, with no flash/warning :face_with_steam_from_nose: ) and after I arrived home I checked the battery to find a dead cell. The max voltage of the battery under 0.5 Amp load was a steady 10,3v. No load voltage of 12.6v.

              In the same day , before I noticed the battery issue, I replaced the main jet to the manual recommended 240 ( from the 190 I was running as a test) and the bike starts to bog the moment you pass the ¾ of the throttle.

              So, will the dead battery make my bike feel over-rich as I go WOT or the two things are not connected ?

              CalumC Offline
              CalumC Offline
              Calum
              wrote on last edited by
              #13

              @panmil92 Yes, if the bike is failing to generate enough power, you won't be able to fire the ignition as many times as necessary. This will result in the engine bogging down due to it misfiring.

              Always Originate, Never Pirate!

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              • CalumC Calum

                @panmil92 Yes, if the bike is failing to generate enough power, you won't be able to fire the ignition as many times as necessary. This will result in the engine bogging down due to it misfiring.

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                panmil92
                wrote on last edited by
                #14

                @Calum Yeah, I was thinking the same… I am attempting to do a single cell charge to try and revive the battery . I’ll look for a new one tomorrow anyways .

                CalumC 1 Reply Last reply
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                • P panmil92

                  @Calum Yeah, I was thinking the same… I am attempting to do a single cell charge to try and revive the battery . I’ll look for a new one tomorrow anyways .

                  CalumC Offline
                  CalumC Offline
                  Calum
                  wrote on last edited by
                  #15

                  @panmil92 I'd be investigating the generator if it were me. At the end of the day, the bike should operate without a battery....

                  Always Originate, Never Pirate!

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                  • CalumC Calum

                    @panmil92 I'd be investigating the generator if it were me. At the end of the day, the bike should operate without a battery....

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                    panmil92
                    wrote on last edited by
                    #16

                    @Calum Hmmm, I measured the voltages at both the charging and the lights outputs. They are exactly on specs. I have no other idea on how to check if the ignition pulses are correct ..

                    If it’s not the battery , then I’m looking again at the rich problem regarding the main jet.

                    CalumC 1 Reply Last reply
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                    • P panmil92

                      @Calum Hmmm, I measured the voltages at both the charging and the lights outputs. They are exactly on specs. I have no other idea on how to check if the ignition pulses are correct ..

                      If it’s not the battery , then I’m looking again at the rich problem regarding the main jet.

                      CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #17

                      @panmil92 Having a faulty battery can cause issues.

                      Always Originate, Never Pirate!

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                      • CalumC Calum

                        @panmil92 Having a faulty battery can cause issues.

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                        panmil92
                        wrote on last edited by
                        #18

                        @Calum It will be my priority tomorrow. I’ll fit a new battery, test the response of the engine under all throttle positions and then if necessary I’ll lean the main jet . I will of course update the thread when I have more information :winking_face:

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                        • 2 Offline
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                          2stroketerry
                          wrote on last edited by
                          #19

                          @panmil92 My 2003 dt 125 r runs exactly the same without the battery and nunning without a battery there is no way at all that it can effect the performance of the bike like @Calum said doesn't make any difference with no battery unless faulty electrics or generator etc. Without battery fitted and multimeter on battery wires when i rev the bike a little it says 15.8 volts

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                          • 2 2stroketerry

                            @panmil92 My 2003 dt 125 r runs exactly the same without the battery and nunning without a battery there is no way at all that it can effect the performance of the bike like @Calum said doesn't make any difference with no battery unless faulty electrics or generator etc. Without battery fitted and multimeter on battery wires when i rev the bike a little it says 15.8 volts

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                            panmil92
                            wrote on last edited by panmil92
                            #20

                            @2stroketerry I have the same voltage reading without the battery, with battery fitted it drops a tiny bit to 15 V.

                            Since the problem only occurs at WOT , I’m leaning towards rich main jet , even though it’s a 240 as stated on manual .

                            I managed to charge the defective cell ( kind of, it holds 2.1v with a 2 amps load ), so I will run a test with the battery charged. If it still bogs at WOT, I will fit a 220 jet and re-test.

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                            • 2 Offline
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                              2stroketerry
                              wrote on last edited by
                              #21

                              @panmil92 The 1997 dt does not use a 240 main jet only the later models have a 240, the correct size main jet for a 1997 dt is a 210.

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                              • 2 2stroketerry

                                @panmil92 The 1997 dt does not use a 240 main jet only the later models have a 240, the correct size main jet for a 1997 dt is a 210.

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                                panmil92
                                wrote on last edited by panmil92
                                #22

                                @2stroketerry Oh , yes, I failed to mention that I run a mikuni TM28ss that was taken from a newer Dt. From the newer engine I took the cylinder ( with the YPVS and servo ), the carburetor and I installed them on my 1997 Dt.

                                Mine had scored the cylinder and somehow the previous owner managed to bend the air way of the carb, that be the reason i replaced them from the back-up engine i have.

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                                • P Offline
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                                  panmil92
                                  wrote on last edited by panmil92
                                  #23

                                  Btw, I was wandering why if the engine is the same they have different jets fitted on the same carburetor through the years ?
                                  Or the engines are not so similar and I’ve made a huge mistake interchanging the cylinders 😐 ( although after 300k kilometers nothing exploded, even at 10k rpms :smiling_face_with_halo: )

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                                  • 2 Offline
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                                    2stroketerry
                                    wrote on last edited by
                                    #24

                                    @panmil92 Depends what cylinder the 1997 engine had on it as the earlier engines have different stroke crankshafts. If the early engine had a 3MB00 cylinder on it then would be fine as the late engines all run the 3MB00 cylinders, also the really late engines have the 3MB high compression head that gives more horsepower compared to the earlier 3BN head with completely different squishband.

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                                    • 2 2stroketerry

                                      @panmil92 Depends what cylinder the 1997 engine had on it as the earlier engines have different stroke crankshafts. If the early engine had a 3MB00 cylinder on it then would be fine as the late engines all run the 3MB00 cylinders, also the really late engines have the 3MB high compression head that gives more horsepower compared to the earlier 3BN head with completely different squishband.

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                                      panmil92
                                      wrote on last edited by panmil92
                                      #25

                                      @2stroketerry If I remember correctly both cylinders had the same number and the same heads ( the 3BN type with the non-flat squishband ) . Now regarding the markings on the crankshaft cover I think they were a little different ( something like Y-1 , and Y-2 ? I’m not sure about this I need to call my brother to check as the donor engine is on a different town )

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                                      • P Offline
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                                        panmil92
                                        wrote on last edited by panmil92
                                        #26

                                        I found a pic, the crankshaft cover on the 1997 bike reads ( 3BN03 )
                                        ----------------------------------------------------------------------------- ( Y-1 )

                                        and from the donor bike it reads ( 3BN03 )
                                        --------------------------------------------(Y-2)
                                        What the second code means anyway ?

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                                        • 2 Offline
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                                          2stroketerry
                                          wrote on last edited by
                                          #27

                                          @panmil92 The number on the cover has nothing to do with engine types years or models as even the latest 4BL engines have 3BN03 Y-1 on the cover.
                                          0_1537574514786_IMAG0254.jpg

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