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    Makita Piston

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    • S
      SpookDog last edited by SpookDog

      Hi! Just got my barrel and Bits’s back from pjme’s and have a question about Makita pistons. where does the ‘crinkly’ backing ring thing go? Top or bottom ring? I know that the top is a keystone ring and the bottom is plain, but i don’t know which one has the backing ring thing...

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      • Calum
        Calum last edited by

        Makita? Cool I never knew they moved into Piston manufacturing now

        alt text

        Is this taking the "Power" band to the next level.

        You mean Mitaka don't you?

        alt text

        I think that's the bottom ring, but I have NEVER bothered fitting it and I've never seen it on any other DTR Piston. RS didn't have one either.

        Make sure you measure the Piston Ring End gap and ensure it's within tolerance!

        Always Originate, Never Pirate!

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        • S
          SpookDog last edited by

          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 😇

          declan 1 Reply Last reply Reply Quote 0
          • Calum
            Calum last edited by

            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!

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            • A
              Arild @Calum last edited by

              @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

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              • D
                DTR+NSR @Arild last edited by

                @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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                • declan
                  declan @SpookDog last edited by

                  @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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                  • A
                    Arild @DTR+NSR last edited by

                    @DTR-NSR

                    Thanks mate👍

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                    • S
                      SpookDog last edited by

                      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

                      declan 1 Reply Last reply Reply Quote 0
                      • declan
                        declan @SpookDog last edited by

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

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                        • S
                          SpookDog last edited by

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

                          declan 1 Reply Last reply Reply Quote 0
                          • Calum
                            Calum last edited by Calum

                            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!

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                            • declan
                              declan @SpookDog last edited by

                              @SpookDog 👌

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                                DTR+NSR @declan last edited by

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

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                                • Calum
                                  Calum last edited by

                                  225PSI! Wow! That's mental.

                                  Always Originate, Never Pirate!

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                                  • D
                                    DTR+NSR @Calum last edited by

                                    @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.

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                                    • Calum
                                      Calum last edited by

                                      Yeah I bet 🤣

                                      Always Originate, Never Pirate!

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                                      • S
                                        SpookDog last edited by

                                        @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

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                                          DTR+NSR @SpookDog last edited by

                                          @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

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                                          • S
                                            SpookDog last edited by

                                            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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