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DT125R FORUM

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  4. Makita Piston

Makita Piston

Scheduled Pinned Locked Moved Engine
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  • A Arild

    @Calum

    Hey Calum, where can these tolerences be found? I suppose its in the service manual? I dont own a manual but maybe its time i pull the trigger on one

    D Offline
    D Offline
    DTR+NSR
    wrote on last edited by
    #6

    @Arild 0.30 - 0.45mm you'll want a decent small file. And only file inwards towards the centre of the ring. I hold the file in a vice and slide the ring along the jaws of the vice to help keep it all square as well.

    A 1 Reply Last reply
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    • S SpookDog

      Yeah. Mitaka. I called it something entirely different in the thread title and edited it to Makita. How embarrassing?!!

      The barrel and piston have just come back from PJME so I trust the tolerance, ect. The barrel is a 3MB and it says TZR on the piston box. Iโ€™ve never had one like this before but I have seen them online in pics, ect.
      The piston that was in before was a wossner. Both the rings looked identical, so I donโ€™t really know what to make of it all. Just want to get it right, what with being the sixteenth โ€˜registeredโ€™ owner. I feel I have a duty of care for the old plodder ๐Ÿ˜‡

      declanD Offline
      declanD Offline
      declan
      wrote on last edited by
      #7

      @SpookDog ive installed one and left one out canโ€™t remember which bikes but the dt probably has one and Iโ€™m sure I tried one with and without on an am6 engine and it appeared to make no difference I donโ€™t actually know what itโ€™s for most people donโ€™t install them.

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      • D DTR+NSR

        @Arild 0.30 - 0.45mm you'll want a decent small file. And only file inwards towards the centre of the ring. I hold the file in a vice and slide the ring along the jaws of the vice to help keep it all square as well.

        A Offline
        A Offline
        Arild
        wrote on last edited by
        #8

        @DTR-NSR

        Thanks mate๐Ÿ‘

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        0
        • S Offline
          S Offline
          SpookDog
          wrote on last edited by
          #9

          Soooo, itโ€™s an expander ring, for bores that have a bit too much clearance. Goes behind the thinner ring, on the bottom of the piston. Not recommended to be fitted if you have a nice tight fresh bore...
          Got an email from PJME

          declanD 1 Reply Last reply
          0
          • S SpookDog

            Soooo, itโ€™s an expander ring, for bores that have a bit too much clearance. Goes behind the thinner ring, on the bottom of the piston. Not recommended to be fitted if you have a nice tight fresh bore...
            Got an email from PJME

            declanD Offline
            declanD Offline
            declan
            wrote on last edited by
            #10

            @SpookDog moar compression!! Will do 109 in 4th gear with that in then

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            • S Offline
              S Offline
              SpookDog
              wrote on last edited by
              #11

              @declan
              Wow, I wish I lived in the same reality as you...
              I think ๐Ÿค”

              declanD 1 Reply Last reply
              0
              • CalumC Offline
                CalumC Offline
                Calum
                wrote on last edited by Calum
                #12

                I mean, typically that's how it goes. The higher the compression the more power. Typically.... You need fueling and ignition timing to accommodate.

                Always Originate, Never Pirate!

                1 Reply Last reply
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                • S SpookDog

                  @declan
                  Wow, I wish I lived in the same reality as you...
                  I think ๐Ÿค”

                  declanD Offline
                  declanD Offline
                  declan
                  wrote on last edited by
                  #13

                  @SpookDog ๐Ÿ‘Œ

                  D 1 Reply Last reply
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                  • declanD declan

                    @SpookDog ๐Ÿ‘Œ

                    D Offline
                    D Offline
                    DTR+NSR
                    wrote on last edited by
                    #14

                    When my dt was running 225psi it had incredible midrange but wouldn't rev high.

                    1 Reply Last reply
                    0
                    • CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #15

                      225PSI! Wow! That's mental.

                      Always Originate, Never Pirate!

                      D 1 Reply Last reply
                      0
                      • CalumC Calum

                        225PSI! Wow! That's mental.

                        D Offline
                        D Offline
                        DTR+NSR
                        wrote on last edited by
                        #16

                        @Calum that was a cold engine aswell! That's with +1mm over bore. Running a mick abbey modded head. Which is quite a few cc's less volume than stock 3mb.
                        Runing two base gaskets and a spacer plate now. To lower the compression which has also raised the port timing. I miss the heaps of midrange but not the bruised foot from kickstarting it lol.

                        1 Reply Last reply
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                        • CalumC Offline
                          CalumC Offline
                          Calum
                          wrote on last edited by
                          #17

                          Yeah I bet ๐Ÿคฃ

                          Always Originate, Never Pirate!

                          1 Reply Last reply
                          0
                          • S Offline
                            S Offline
                            SpookDog
                            wrote on last edited by
                            #18

                            @declan
                            Sorry, didnโ€™t mean to offend. Plus I gave ๐Ÿ‘ƒ๐Ÿ‘Œ up a looooong time ago! ๐Ÿ™‚

                            In all seriousness, Iโ€™d like to know what the cc of a 3MB head is? Mine had to be reprofiled to get rid of piston ring explosion marks and Iโ€™m not sure if it was skimmed to the point that it kept the same compression ratio

                            D 1 Reply Last reply
                            0
                            • S SpookDog

                              @declan
                              Sorry, didnโ€™t mean to offend. Plus I gave ๐Ÿ‘ƒ๐Ÿ‘Œ up a looooong time ago! ๐Ÿ™‚

                              In all seriousness, Iโ€™d like to know what the cc of a 3MB head is? Mine had to be reprofiled to get rid of piston ring explosion marks and Iโ€™m not sure if it was skimmed to the point that it kept the same compression ratio

                              D Offline
                              D Offline
                              DTR+NSR
                              wrote on last edited by
                              #19

                              @SpookDog I measured one of my heads at 13cc, unfortunately can't remember which. The dome of the +1mm mitaka piston measures at 3.5cc though : p

                              1 Reply Last reply
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                              • S Offline
                                S Offline
                                SpookDog
                                wrote on last edited by
                                #20

                                Cheers bud, thatโ€™s something to work with. Iโ€™ve got a good 3bn, my reworked 3mb and another 3mb (that I forgot about till now) that is battle~scarred but otherwise original.

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