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DT125R FORUM

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  4. Time to change wheels and ...

Time to change wheels and ...

Scheduled Pinned Locked Moved Top End
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  • CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #11

    Embed me!

    alt text

    Yeah, you can bore that out no problems.

    Ensure you modify the powervalve to the right spec. Otherwise you will risk having the powervalve come into contact with the piston.

    Always Originate, Never Pirate!

    1 Reply Last reply
    0
    • Y Offline
      Y Offline
      Yegor
      wrote on last edited by
      #12

      @Calum You mean just adjust the power valve position ? ( cables ) Thx !

      CalumC Irongamer727I 3 Replies Last reply
      0
      • Y Yegor

        @Calum You mean just adjust the power valve position ? ( cables ) Thx !

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

        @yegor No, you physically have the modify the powervalve after a rebore.

        Always Originate, Never Pirate!

        1 Reply Last reply
        0
        • Y Yegor

          @Calum You mean just adjust the power valve position ? ( cables ) Thx !

          Irongamer727I Offline
          Irongamer727I Offline
          Irongamer727
          wrote on last edited by
          #14

          @yegor Athena!

          1 Reply Last reply
          0
          • Y Yegor

            @Calum You mean just adjust the power valve position ? ( cables ) Thx !

            Irongamer727I Offline
            Irongamer727I Offline
            Irongamer727
            wrote on last edited by
            #15

            @yegor but sort out why it seized first please😉

            1 Reply Last reply
            0
            • Y Offline
              Y Offline
              Yegor
              wrote on last edited by
              #16

              @Calum thx again! do you know how to extract the power valve from the cylinder ? ( for cleaning and modify )

              @Irongamer727 Ok ! )) Do you need to readjust the oil lubrication after install the Athena kit ?

              Thx a lot .

              Irongamer727I 1 Reply Last reply
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              • CalumC Offline
                CalumC Offline
                Calum
                wrote on last edited by
                #17

                There is a bolt that goes through the powervalve, can be unscrewed from the front right of the cylinder. Behind the powervalve cover from the clutch cover side.

                Always Originate, Never Pirate!

                1 Reply Last reply
                0
                • Y Yegor

                  @Calum thx again! do you know how to extract the power valve from the cylinder ? ( for cleaning and modify )

                  @Irongamer727 Ok ! )) Do you need to readjust the oil lubrication after install the Athena kit ?

                  Thx a lot .

                  Irongamer727I Offline
                  Irongamer727I Offline
                  Irongamer727
                  wrote on last edited by
                  #18

                  @yegor some go premix some don't. I will go with the pump when installing my kit

                  1 Reply Last reply
                  0
                  • J Offline
                    J Offline
                    Jens Eskildsen
                    wrote on last edited by
                    #19

                    A slight rebore shouldn't affect the powervalve 🙂

                    CalumC 1 Reply Last reply
                    0
                    • J Jens Eskildsen

                      A slight rebore shouldn't affect the powervalve 🙂

                      CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #20

                      @jens-eskildsen Yes it will.

                      If the bore is stock (getting rarer these days and not worth assuming) then no, you're right. But once you start going over the first rebore size, modifying the valve is a must.

                      To save confusing, I said modify the valve just as a precaution.

                      Always Originate, Never Pirate!

                      1 Reply Last reply
                      0
                      • Y Offline
                        Y Offline
                        Yegor
                        wrote on last edited by
                        #21

                        Yes, the cylinder was rebored at least once. Now I'm looking where do that again. Thx !!

                        @Calum > ?
                        0_1512655186767_IMG_20171205_163718.jpg

                        CalumC 1 Reply Last reply
                        0
                        • Y Yegor

                          Yes, the cylinder was rebored at least once. Now I'm looking where do that again. Thx !!

                          @Calum > ?
                          0_1512655186767_IMG_20171205_163718.jpg

                          CalumC Offline
                          CalumC Offline
                          Calum
                          wrote on last edited by
                          #22

                          @yegor Yeah that's the pup.

                          Always Originate, Never Pirate!

                          1 Reply Last reply
                          0
                          • Y Offline
                            Y Offline
                            Yegor
                            wrote on last edited by
                            #23

                            @Calum **thanks to everyone ** . One question ( maybe a little bit stupid) XD . What material the cylinder is made of ? And the cylinder sleeve ? ( Yamaha DT 125R )

                            The cylinder sleeve Iron?
                            Cylinder Aluminium ?

                            Have you tuned Yamaha cylinder ? ( admision / exhaust transfers etc ?)

                            Cheers !

                            CalumC 1 Reply Last reply
                            0
                            • Y Yegor

                              @Calum **thanks to everyone ** . One question ( maybe a little bit stupid) XD . What material the cylinder is made of ? And the cylinder sleeve ? ( Yamaha DT 125R )

                              The cylinder sleeve Iron?
                              Cylinder Aluminium ?

                              Have you tuned Yamaha cylinder ? ( admision / exhaust transfers etc ?)

                              Cheers !

                              CalumC Offline
                              CalumC Offline
                              Calum
                              wrote on last edited by
                              #24

                              @yegor YEah that's correct. I imagine the bore will be a steel alloy.

                              I've had my barrel ported by a tuner.

                              Always Originate, Never Pirate!

                              declanD 1 Reply Last reply
                              0
                              • CalumC Calum

                                @yegor YEah that's correct. I imagine the bore will be a steel alloy.

                                I've had my barrel ported by a tuner.

                                declanD Offline
                                declanD Offline
                                declan
                                wrote on last edited by
                                #25

                                @calum how much did that cost bud and can it just bolt back on no jet changes etc

                                CalumC 1 Reply Last reply
                                0
                                • declanD declan

                                  @calum how much did that cost bud and can it just bolt back on no jet changes etc

                                  CalumC Offline
                                  CalumC Offline
                                  Calum
                                  wrote on last edited by
                                  #26

                                  @declan No, porting is going to drastically change the characteristics of a two stroke engine.

                                  I wouldn't advise it on a daily, or on stock ignition.

                                  You don't get something for nothing. I'm not going into it here, but the principle is, peak almost always alters performance elsewhere, usually torque.

                                  There are exceptions where engines are poorly designed and modifications improve performance with no effect. But the end of it is, these engines are pretty well designed. When it comes to porting them, you're making a sacrafice somewhere else in the rev range for more power.

                                  Always Originate, Never Pirate!

                                  1 Reply Last reply
                                  1
                                  • Y Offline
                                    Y Offline
                                    Yegor
                                    wrote on last edited by
                                    #27

                                    Hello ) !
                                    I will go tomorrow to the workshop with the cylinder for bore. I know is privileged information and long testing time but do you know where I can find information about tuning cylinder transfers, I think is good idea do something there before it will be bored. Maybe in the same workshop they do that for extra €, will ask.

                                    all this marked with color dots can be modified/enlarged : ?
                                    0_1513007430177_cilindro marcado.jpg
                                    at the top of ALL the transfers: (?)
                                    0_1513007813829_IMG_20171205_163907.jpg

                                    so, thank you again for the help, and gas gas !

                                    1 Reply Last reply
                                    0
                                    • CalumC Offline
                                      CalumC Offline
                                      Calum
                                      wrote on last edited by
                                      #28

                                      Depending on how good your English reading is, I HIGHLY recommend Graham Bell's Two Stroke Performance Tuning.

                                      That will give you a lot of knowledge on tuning two strokes.

                                      I would NOT recommend porting the barrel, or altering the port timings, without a programmable CDI.

                                      Always Originate, Never Pirate!

                                      1 Reply Last reply
                                      0
                                      • Y Offline
                                        Y Offline
                                        Yegor
                                        wrote on last edited by Yegor
                                        #29

                                        @calum said in Time to change wheels and ...:

                                        Graham Bell's Two Stroke Performance Tuning

                                        Thanks for the tip Calum . also I have dowloaded the Two-Stroke TUNER'S HANDBOOK By Gordon Jennings. Time to read.
                                        ( http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php )

                                        so, for now I'm going to polish a little bit where it is needed , also the power valve , because it is very dirty.
                                        Mitaka pistons are good ? where you can buy original Yamaha DT R parts online ( like water pump complete repair kit) ? <--- have find this official site : http://www.recambios-yamaha.com/es/dt125r/2002/bomba-de-agua.html

                                        Thank you very much everyone, your answers are very useful.

                                        CalumC 1 Reply Last reply
                                        0
                                        • Y Yegor

                                          @calum said in Time to change wheels and ...:

                                          Graham Bell's Two Stroke Performance Tuning

                                          Thanks for the tip Calum . also I have dowloaded the Two-Stroke TUNER'S HANDBOOK By Gordon Jennings. Time to read.
                                          ( http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php )

                                          so, for now I'm going to polish a little bit where it is needed , also the power valve , because it is very dirty.
                                          Mitaka pistons are good ? where you can buy original Yamaha DT R parts online ( like water pump complete repair kit) ? <--- have find this official site : http://www.recambios-yamaha.com/es/dt125r/2002/bomba-de-agua.html

                                          Thank you very much everyone, your answers are very useful.

                                          CalumC Offline
                                          CalumC Offline
                                          Calum
                                          wrote on last edited by
                                          #30

                                          @yegor I'd recommend PJME, they're based in England but are Two Stroke Specialist, I believe they ship world wide.

                                          Polishing will get you so far, gasket matching is going to be far more effective.

                                          If you're going for performance, I'd avoid mitaka. Nothing wrong with them, but they are cheap CAST pistons designed to offer a cheap alternative to OEM.

                                          For performance, go forged. Grab yourself a forged Wiesco piston and a set of chromium rings.

                                          Always Originate, Never Pirate!

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