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DT125R FORUM

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  4. Makita Piston

Makita Piston

Scheduled Pinned Locked Moved Engine
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  • CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #4

    I wouldn't assume anything. Checking the ring gap will take you 60 seconds per ring.

    It's literally just placing the rings at the top of the bore. Use the piston to push it a few centimetres in and making sure it's square. Then using a feeler guage to measure the gap where the rings butt. It should reside within tolerance.

    I find the Wossner ones always supply one ring out of spec. Presumably so you can fine tune it yourself.

    Do that for both rings make sure they are tip top. Then whack them in and away you go.

    Always Originate, Never Pirate!

    A 1 Reply Last reply
    0
    • CalumC Calum

      I wouldn't assume anything. Checking the ring gap will take you 60 seconds per ring.

      It's literally just placing the rings at the top of the bore. Use the piston to push it a few centimetres in and making sure it's square. Then using a feeler guage to measure the gap where the rings butt. It should reside within tolerance.

      I find the Wossner ones always supply one ring out of spec. Presumably so you can fine tune it yourself.

      Do that for both rings make sure they are tip top. Then whack them in and away you go.

      A Offline
      A Offline
      Arild
      wrote on last edited by
      #5

      @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 1 Reply Last reply
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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.

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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. I’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 don’t really know what to make of it all. Just want to get it right, what with being the sixteenth ‘registered’ owner. I feel I have a duty of care for the old plodder 😇

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

          @SpookDog ive installed one and left one out can’t remember which bikes but the dt probably has one and I’m sure I tried one with and without on an am6 engine and it appeared to make no difference I don’t actually know what it’s for most people don’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 mate👍

            1 Reply Last reply
            0
            • S Offline
              S Offline
              SpookDog
              wrote on last edited by
              #9

              Soooo, it’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, it’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

                1 Reply Last reply
                0
                • 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 🤔

                  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
                    0
                    • S SpookDog

                      @declan
                      Wow, I wish I lived in the same reality as you...
                      I think 🤔

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

                      @SpookDog 👌

                      D 1 Reply Last reply
                      0
                      • declanD declan

                        @SpookDog 👌

                        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
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                        • 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 🤣

                              Always Originate, Never Pirate!

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

                                @declan
                                Sorry, didn’t mean to offend. Plus I gave 👃👌 up a looooong time ago! 🙂

                                In all seriousness, I’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 I’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, didn’t mean to offend. Plus I gave 👃👌 up a looooong time ago! 🙂

                                  In all seriousness, I’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 I’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, that’s something to work with. I’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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