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DT125R FORUM

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  4. Yamaha DT 125 DERESTRICTING

Yamaha DT 125 DERESTRICTING

Scheduled Pinned Locked Moved Derestricting
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  • L Offline
    L Offline
    Lukas55
    wrote on last edited by
    #21

    Here is video of power valve, maybe its something wrong with it... If video quality is bad I will make better one tomorrow...
    https://youtu.be/naA3Zt0piGs

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    • L Lukas55

      Here is video of power valve, maybe its something wrong with it... If video quality is bad I will make better one tomorrow...
      https://youtu.be/naA3Zt0piGs

      D Offline
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      DTR+NSR
      wrote on last edited by
      #22

      @Lukas55 the powervalve seems to operate as expected. It'd be worth taking the exhaust off to see if the valve is in the open position when it's supposed to be. It can be fitted 180° out. And to check there's no restrict ions in the exhuast it self.

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      • D DTR+NSR

        @Lukas55 the powervalve seems to operate as expected. It'd be worth taking the exhaust off to see if the valve is in the open position when it's supposed to be. It can be fitted 180° out. And to check there's no restrict ions in the exhuast it self.

        L Offline
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        Lukas55
        wrote on last edited by
        #23

        @DTR-NSR I will check that tomorrow. One more question, so is there any chance of putting different CDI with higher rev limiter?

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        • L Lukas55

          @DTR-NSR I will check that tomorrow. One more question, so is there any chance of putting different CDI with higher rev limiter?

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          DTR+NSR
          wrote on last edited by
          #24

          @Lukas55 yours looks to have a earlier cdi which are considered the best.

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          • D DTR+NSR

            @Lukas55 yours looks to have a earlier cdi which are considered the best.

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            Lukas55
            wrote on last edited by
            #25

            @DTR-NSR Hmmm okay, that's great. It tops at 5500 rpms in 6 gear so it must be because of exhaust...

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            • S Offline
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              SpookDog
              wrote on last edited by
              #26

              In my opinion, If it’s only doing 50mph, it’s not because of restrictions, it’s cause there is something wrong with it...
              How long have you had the bike? Has it always been so slow? It might just be rebuilding time...

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              • L Offline
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                Lukas55
                wrote on last edited by
                #27

                I have it for about 3 months and it was like that when I bought it. It had 13-57 gearing so I thought it's because of that but when I bought 16t front sprocket then I noticed it's something wrong... The piston and bearings in the crankshaft are changed 400km ago...

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                • L Offline
                  L Offline
                  Lukas55
                  wrote on last edited by
                  #28

                  I removed the exhaust and the piston looks like this...
                  https://i.postimg.cc/Bj4tBnD6/adw.jpg
                  https://i.postimg.cc/xcrXqR1L/daw.jpg
                  https://i.postimg.cc/ykFkRZDt/daws.jpg

                  Btw is YVPS set good? Is it supposed to look like that in the cylinder?

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                  • L Lukas55

                    I removed the exhaust and the piston looks like this...
                    https://i.postimg.cc/Bj4tBnD6/adw.jpg
                    https://i.postimg.cc/xcrXqR1L/daw.jpg
                    https://i.postimg.cc/ykFkRZDt/daws.jpg

                    Btw is YVPS set good? Is it supposed to look like that in the cylinder?

                    declanD Offline
                    declanD Offline
                    declan
                    wrote on last edited by
                    #29

                    @Lukas55 looks like the ypvs can be set better did you have proof that the piston was changed

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                    • declanD declan

                      @Lukas55 looks like the ypvs can be set better did you have proof that the piston was changed

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                      L Offline
                      Lukas55
                      wrote on last edited by
                      #30

                      @declan
                      No ... Very stupid mistake, Next time I'll take off the exhaust to check ...Never can't trust people I guess.

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                      • L Lukas55

                        @declan
                        No ... Very stupid mistake, Next time I'll take off the exhaust to check ...Never can't trust people I guess.

                        declanD Offline
                        declanD Offline
                        declan
                        wrote on last edited by
                        #31

                        @Lukas55 the piston doesn't look too bad just doubt it was changed

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                        • declanD declan

                          @Lukas55 the piston doesn't look too bad just doubt it was changed

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                          DTR+NSR
                          wrote on last edited by
                          #32

                          Does it rev higher in the other gears? The powervalve looks ok.

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                          • L Offline
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                            Lukas55
                            wrote on last edited by
                            #33

                            Yes it revs little bit higher in lower gears.

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                            • S Offline
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                              SpookDog
                              wrote on last edited by
                              #34

                              I’m pretty sure that my power valve is set in the fully open position when the ignition is off. If you have a working power valve servo it’s set wrong...

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                              • S Offline
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                                SpookDog
                                wrote on last edited by SpookDog
                                #35

                                All you’re gonna have to do is undo the pulley bolt and rotate the power valve till it’s ‘smooth’ with the exhaust port and refit the pulley. It should cycle closed then open when you turn on the ignition. It should only close again when you run the engine...
                                Should take you 30 mins, then enjoy!! 😜

                                P.S. there’s a good chance that you will have to adjust the cables as well. Just make sure that the power valve is at the open/smooth position, that the pulley pointer/thing is set towards the little 3mm hole and adjust to fit..

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                                • S Offline
                                  S Offline
                                  SpookDog
                                  wrote on last edited by
                                  #36

                                  By the way you have the power valve set I’m guessing you don’t really get past 7000 rpm in any gear?...

                                  I have an early Dtr like yours. I also have a working power valve servo fitted. Finding out information on how to properly fit it was nearly impossible. I had to watch videos of 3wire servos starting up on ignition then running. I don’t know about later 5wire servos, but your power valve needs to be set in the ‘pinned open’ position when the engine isn’t running. The way it is set at the moment it is restricted and the servo will only try to close it more. It’s a wonder that it runs any sense at all the way it’s set...

                                  CalumC 1 Reply Last reply
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                                  • S SpookDog

                                    By the way you have the power valve set I’m guessing you don’t really get past 7000 rpm in any gear?...

                                    I have an early Dtr like yours. I also have a working power valve servo fitted. Finding out information on how to properly fit it was nearly impossible. I had to watch videos of 3wire servos starting up on ignition then running. I don’t know about later 5wire servos, but your power valve needs to be set in the ‘pinned open’ position when the engine isn’t running. The way it is set at the moment it is restricted and the servo will only try to close it more. It’s a wonder that it runs any sense at all the way it’s set...

                                    CalumC Offline
                                    CalumC Offline
                                    Calum
                                    wrote on last edited by
                                    #37

                                    @SpookDog That's how I usually set my valve.

                                    I've never encountered problems aligning the valve.

                                    Going from a completely broken setup to work.

                                    Turn ignition on and off. This is how the powervalve should be when it is fully open.

                                    So it is just a case of adjusting the cables so that the valve is flush with the exhaust port. In some instances people have put the cables around the wrong way so that it is not operating correctly. But that's easily rectified.

                                    Always Originate, Never Pirate!

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                                      SpookDog
                                      wrote on last edited by
                                      #38

                                      Yeah, the cables are clearly numbered 1 & 2. In my case they didn’t match up. I had to cut some outer off of one as well, to make it fit and work. 😐 unbelievable!

                                      Getting the power valve fitted and the servo working was like one of the biggest mine-fields since the Somme ☠️

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                                      • S SpookDog

                                        Yeah, the cables are clearly numbered 1 & 2. In my case they didn’t match up. I had to cut some outer off of one as well, to make it fit and work. 😐 unbelievable!

                                        Getting the power valve fitted and the servo working was like one of the biggest mine-fields since the Somme ☠️

                                        L Offline
                                        L Offline
                                        Lukas55
                                        wrote on last edited by
                                        #39

                                        @SpookDog Thanks for advance dude!

                                        1 Reply Last reply
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                                        • L Offline
                                          L Offline
                                          Lukas55
                                          wrote on last edited by
                                          #40

                                          Does my DT sound properly?
                                          https://youtu.be/Id1jsvah8T8

                                          declanD 1 Reply Last reply
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