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DT125R FORUM

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  4. Hmm now what (A Rebore!)

Hmm now what (A Rebore!)

Scheduled Pinned Locked Moved Engine
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  • P Pablo13

    @Calum alt text

    :crying_face:

    Still not stripped, but my best guess is a snapped ring right now. That is what you get for forgetting to pull the clutch in I guess.

    CalumC Online
    CalumC Online
    Calum
    wrote on last edited by
    #9

    @Pablo13 Not at all mate.

    The bike would have been tested heavily to slam the brakes on without engine failure.

    Something would have gone eventually.

    Either engine was due an overhaul, or it wasn't built within tolerance, or any number of reasons.

    You applying the brakes should not have killed the engine, that would be a shit design.

    Always Originate, Never Pirate!

    declanD 1 Reply Last reply
    1
    • Irongamer727I Offline
      Irongamer727I Offline
      Irongamer727
      wrote on last edited by
      #10

      Little off topic, what compression in bars should a healthy dt125 have?

      P 1 Reply Last reply
      0
      • Irongamer727I Irongamer727

        Little off topic, what compression in bars should a healthy dt125 have?

        P Offline
        P Offline
        Pablo13
        wrote on last edited by
        #11

        @Irongamer727 The manual indicates 6.8 πŸ˜‰

        1 Reply Last reply
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        • CalumC Calum

          @Pablo13 Not at all mate.

          The bike would have been tested heavily to slam the brakes on without engine failure.

          Something would have gone eventually.

          Either engine was due an overhaul, or it wasn't built within tolerance, or any number of reasons.

          You applying the brakes should not have killed the engine, that would be a shit design.

          declanD Offline
          declanD Offline
          declan
          wrote on last edited by
          #12

          @Calum does he maybe mean he engine braked?

          CalumC 1 Reply Last reply
          0
          • declanD declan

            @Calum does he maybe mean he engine braked?

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

            @declan Two strokes don't really engine brake though.

            Always Originate, Never Pirate!

            1 Reply Last reply
            0
            • P Offline
              P Offline
              Pablo13
              wrote on last edited by
              #14

              Oooo err, its a bit of a mess in there, hang on....

              1 Reply Last reply
              0
              • P Offline
                P Offline
                Pablo13
                wrote on last edited by
                #15

                https://farm5.staticflickr.com/4829/32868499598_e399f7de9c_z.jpg

                alt text

                alt text

                Piston is shagged, looks like something has got in or been in there for a while bouncing about, plus det marks, there is even a low spot on the crown from det. The Head I'm most concerned with hopefully it will tidy up. The bore isnt too sad at all, a light rebore should do it, new piston and see what happens lets hope πŸ™‚

                NINJAN 1 Reply Last reply
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                • P Pablo13

                  https://farm5.staticflickr.com/4829/32868499598_e399f7de9c_z.jpg

                  alt text

                  alt text

                  Piston is shagged, looks like something has got in or been in there for a while bouncing about, plus det marks, there is even a low spot on the crown from det. The Head I'm most concerned with hopefully it will tidy up. The bore isnt too sad at all, a light rebore should do it, new piston and see what happens lets hope πŸ™‚

                  NINJAN Offline
                  NINJAN Offline
                  NINJA
                  wrote on last edited by NINJA
                  #16

                  @Pablo13 Yep that looks well fooked for-sure. I would also check the bottom end for any loose fragments floating about, just to be sure. Get one of these and give it a couple of swirls to pick up any debris floating around. πŸ˜‰

                  https://www.ebay.co.uk/itm/New-Flexible-Magnetic-Pick-Up-Long-Reach-Strong-Magnet-Grabber-Stick-w-Light-UK/113535422657?hash=item1a6f3d10c1β“‚mUSgt17pTEhDHzy-QODYJNQ:rk:33:pf:0

                  SEDUCED BY THE DARK SIDE!!!

                  P 1 Reply Last reply
                  0
                  • NINJAN NINJA

                    @Pablo13 Yep that looks well fooked for-sure. I would also check the bottom end for any loose fragments floating about, just to be sure. Get one of these and give it a couple of swirls to pick up any debris floating around. πŸ˜‰

                    https://www.ebay.co.uk/itm/New-Flexible-Magnetic-Pick-Up-Long-Reach-Strong-Magnet-Grabber-Stick-w-Light-UK/113535422657?hash=item1a6f3d10c1β“‚mUSgt17pTEhDHzy-QODYJNQ:rk:33:pf:0

                    P Offline
                    P Offline
                    Pablo13
                    wrote on last edited by
                    #17

                    @NINJA I'll have a little fishing session with some magnets and see if I can find anything left behind.

                    NINJAN 1 Reply Last reply
                    1
                    • P Pablo13

                      @NINJA I'll have a little fishing session with some magnets and see if I can find anything left behind.

                      NINJAN Offline
                      NINJAN Offline
                      NINJA
                      wrote on last edited by
                      #18

                      @Pablo13 I would be surprised if the heavy braking incident caused all that damage, by the looks of it your engine was in decline and had suffered some internal damage most likely from detonation, over an extended period of time. The incident was just the tip of the iceberg and the straw the finally broke the camel's back. You were dead lucky the engine maintained power and you were still able to ride her home. Sadly the price we all have to pay from owning a used bike and not knowing the true history of our pride n' joy.

                      SEDUCED BY THE DARK SIDE!!!

                      P 1 Reply Last reply
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                      • NINJAN NINJA

                        @Pablo13 I would be surprised if the heavy braking incident caused all that damage, by the looks of it your engine was in decline and had suffered some internal damage most likely from detonation, over an extended period of time. The incident was just the tip of the iceberg and the straw the finally broke the camel's back. You were dead lucky the engine maintained power and you were still able to ride her home. Sadly the price we all have to pay from owning a used bike and not knowing the true history of our pride n' joy.

                        P Offline
                        P Offline
                        Pablo13
                        wrote on last edited by
                        #19

                        @NINJA Yeah I agree. She is a French import, although it was the runt of the litter so to speak, and had expected stuff to go wrong and I guess the mileage is about right for a top end. Just surprised that any plugs I pulled looked fine and it always started first or second kick right up until that incident.

                        I've run it on super while I've had it, so I guess it must have had some crap French fuel a while back and just managed to hold it together pootling about French lanes until I got my hands on it :grinning_face:

                        On the upside this may well go to explaining why it wasn't too happy revving over 9k, so if it solves that issue at the same time, I'll be happy. 0.5mm oversize piston, small end and gaskets have been ordered today and the bore and head are at the machinists. Hoping for a quick turnaround :grimacing_face:

                        NINJAN 1 Reply Last reply
                        1
                        • D Offline
                          D Offline
                          DTR+NSR
                          wrote on last edited by
                          #20

                          Hard to tell in the pic but looks like the gudgeon pin circlip is missing? Unless you took it out before pic.

                          J 1 Reply Last reply
                          0
                          • CalumC Online
                            CalumC Online
                            Calum
                            wrote on last edited by
                            #21

                            You will want to send that head off to be sorted out as well.

                            Always Originate, Never Pirate!

                            declanD 1 Reply Last reply
                            0
                            • CalumC Calum

                              You will want to send that head off to be sorted out as well.

                              declanD Offline
                              declanD Offline
                              declan
                              wrote on last edited by
                              #22

                              @Calum yeah you could normally get away with a few dents but that’s completely savaged lol

                              1 Reply Last reply
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                              • P Pablo13

                                @NINJA Yeah I agree. She is a French import, although it was the runt of the litter so to speak, and had expected stuff to go wrong and I guess the mileage is about right for a top end. Just surprised that any plugs I pulled looked fine and it always started first or second kick right up until that incident.

                                I've run it on super while I've had it, so I guess it must have had some crap French fuel a while back and just managed to hold it together pootling about French lanes until I got my hands on it :grinning_face:

                                On the upside this may well go to explaining why it wasn't too happy revving over 9k, so if it solves that issue at the same time, I'll be happy. 0.5mm oversize piston, small end and gaskets have been ordered today and the bore and head are at the machinists. Hoping for a quick turnaround :grimacing_face:

                                NINJAN Offline
                                NINJAN Offline
                                NINJA
                                wrote on last edited by NINJA
                                #23

                                @Pablo13 If you have the cash a full rebuild with a few upgrades aka a modified head to alter the squish would be just the ticket and add more πŸπŸ’¨ !!! πŸ˜‰

                                SEDUCED BY THE DARK SIDE!!!

                                1 Reply Last reply
                                0
                                • D DTR+NSR

                                  Hard to tell in the pic but looks like the gudgeon pin circlip is missing? Unless you took it out before pic.

                                  J Offline
                                  J Offline
                                  Jens Eskildsen
                                  wrote on last edited by
                                  #24

                                  @DTR-NSR said in Hmm now what (A Rebore!):

                                  Hard to tell in the pic but looks like the gudgeon pin circlip is missing? Unless you took it out before pic.

                                  Yeah, and scratches on the side and dome of the piston right about at that point.
                                  Good eyes.

                                  1 Reply Last reply
                                  0
                                  • CalumC Online
                                    CalumC Online
                                    Calum
                                    wrote on last edited by
                                    #25

                                    That grey discolouring on the piston looks like death ash, but I suspect that's a result of the failure.

                                    The head does not look like detonation, looks like something has been crushed into it.

                                    alt text
                                    That's what detonation looks like

                                    Always Originate, Never Pirate!

                                    P 1 Reply Last reply
                                    1
                                    • CalumC Calum

                                      That grey discolouring on the piston looks like death ash, but I suspect that's a result of the failure.

                                      The head does not look like detonation, looks like something has been crushed into it.

                                      alt text
                                      That's what detonation looks like

                                      P Offline
                                      P Offline
                                      Pablo13
                                      wrote on last edited by
                                      #26

                                      @Calum it does have those det marks, they are just hidden under the other damage πŸ˜‚

                                      Dropped the new piston off today, should be back wih the head and bore tomorrow. Gasket set is here too, so if I get a moment I'll get something done on it over the weekend πŸ˜‰

                                      NINJAN 1 Reply Last reply
                                      0
                                      • CalumC Online
                                        CalumC Online
                                        Calum
                                        wrote on last edited by
                                        #27

                                        Yes, but I suspect that's a result of the engine going faulty and you continuing to run it. Either way, that bike will be down on power now.

                                        If the engine was detonating before the incident, then you will definitely want to sort that out, otherwise you'll just kill another engine.

                                        Always Originate, Never Pirate!

                                        1 Reply Last reply
                                        0
                                        • P Pablo13

                                          @Calum it does have those det marks, they are just hidden under the other damage πŸ˜‚

                                          Dropped the new piston off today, should be back wih the head and bore tomorrow. Gasket set is here too, so if I get a moment I'll get something done on it over the weekend πŸ˜‰

                                          NINJAN Offline
                                          NINJAN Offline
                                          NINJA
                                          wrote on last edited by
                                          #28

                                          @Pablo13 Either way not getting that head fixed would only lead to further problems down the road. Take & post some pics of the newly refurbed parts before you refit them please dude. πŸ˜‰

                                          SEDUCED BY THE DARK SIDE!!!

                                          P 1 Reply Last reply
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