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DT125R FORUM

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  3. YVPS.

YVPS.

Scheduled Pinned Locked Moved Technical Zone
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  • A andrewj1680

    @Kieron12345 I've seen it where it's fried the piston All down the front with the power valve shut too where it can't get the exhaust gasses out quick enough apparently, It's 2 stroke it's gonna go through pistons no matter how you ride it so you may aswell get the most out of it

    MightymanM Offline
    MightymanM Offline
    Mightyman
    wrote on last edited by
    #10

    @andrewj1680 that really doesn't seem very accurate to me...

    TDR 125 - 2001

    CalumC A 2 Replies Last reply
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    • MightymanM Mightyman

      @andrewj1680 that really doesn't seem very accurate to me...

      CalumC Online
      CalumC Online
      Calum
      wrote on last edited by
      #11

      @Mightyman Frying pistons? Yeah that sounds about right to me.

      Having the powervalve pinned open damages the engine as it puts undue stress on the bottom end.

      You are talking about reducing its life by a fraction. As Andrew says, pistons are serviceable items on two smokes.

      Always Originate, Never Pirate!

      MightymanM 1 Reply Last reply
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      • MightymanM Mightyman

        @andrewj1680 that really doesn't seem very accurate to me...

        A Offline
        A Offline
        andrewj1680
        wrote on last edited by
        #12

        @Mightyman I've seen it first hand mate it melts the front of the piston dead in line with the exhaust port, I personally pinned the power valve with the idea it's 2 stroke it's gonna want rebuilding from time to time

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        • CalumC Calum

          @Mightyman Frying pistons? Yeah that sounds about right to me.

          Having the powervalve pinned open damages the engine as it puts undue stress on the bottom end.

          You are talking about reducing its life by a fraction. As Andrew says, pistons are serviceable items on two smokes.

          MightymanM Offline
          MightymanM Offline
          Mightyman
          wrote on last edited by
          #13

          @Calum I meant when @andrewj1680 said he has seen a piston fried because the power valve was shut not letting the exhaust gasses out quick enough. @andrewj1680 are you sure it wasn't just coming into contact with the power valve? As they do need shaving down if the cylinder has been rebored.

          TDR 125 - 2001

          A 1 Reply Last reply
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          • MightymanM Mightyman

            @Calum I meant when @andrewj1680 said he has seen a piston fried because the power valve was shut not letting the exhaust gasses out quick enough. @andrewj1680 are you sure it wasn't just coming into contact with the power valve? As they do need shaving down if the cylinder has been rebored.

            A Offline
            A Offline
            andrewj1680
            wrote on last edited by andrewj1680
            #14

            @Mightyman 0_1494937297359_Screenshot_2017-05-16-13-19-20-1.png
            That's result of a piston hitting a power valve the cylinder melting shows the carbon buildup etc I know the difference

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            • CalumC Online
              CalumC Online
              Calum
              wrote on last edited by
              #15

              When the servo is operated there is no risk of this happening.

              With the servo pinned shut, yeah I could see why this would happen.

              Always Originate, Never Pirate!

              1 Reply Last reply
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              • MightymanM Offline
                MightymanM Offline
                Mightyman
                wrote on last edited by
                #16

                I must be getting the wrong end of the stick here, but are you saying that from the factory, a restricted DT (ie servo not operating) has a chance of the front of the piston melting because of the exhaust gases not getting out of the cylinder fast enough...?

                TDR 125 - 2001

                CalumC 1 Reply Last reply
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                • MightymanM Mightyman

                  I must be getting the wrong end of the stick here, but are you saying that from the factory, a restricted DT (ie servo not operating) has a chance of the front of the piston melting because of the exhaust gases not getting out of the cylinder fast enough...?

                  CalumC Online
                  CalumC Online
                  Calum
                  wrote on last edited by
                  #17

                  @Mightyman The Powervalves from the factory were pinned open, not shut.

                  It styfuls the engine having the valve shut.

                  The exhaust is unable to scavenge effectively and reduce the NoX gaes, as a result the engine goes into detonation, which is an engine killer.

                  Now that's the theory, I don't know whether the DT is tuned enough to do this. But I don't doubt its possibility.

                  Always Originate, Never Pirate!

                  MightymanM 1 Reply Last reply
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                  • CalumC Calum

                    @Mightyman The Powervalves from the factory were pinned open, not shut.

                    It styfuls the engine having the valve shut.

                    The exhaust is unable to scavenge effectively and reduce the NoX gaes, as a result the engine goes into detonation, which is an engine killer.

                    Now that's the theory, I don't know whether the DT is tuned enough to do this. But I don't doubt its possibility.

                    MightymanM Offline
                    MightymanM Offline
                    Mightyman
                    wrote on last edited by
                    #18

                    @Calum even DTREs were pinned open from factory?! I thought they were restricted to conform to the 15bhp limit of younger riders? Surely pinned open they would have the full power at higher revs?

                    TDR 125 - 2001

                    CalumC 1 Reply Last reply
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                    • MightymanM Mightyman

                      @Calum even DTREs were pinned open from factory?! I thought they were restricted to conform to the 15bhp limit of younger riders? Surely pinned open they would have the full power at higher revs?

                      CalumC Online
                      CalumC Online
                      Calum
                      wrote on last edited by Calum
                      #19

                      @Mightyman Nah the DTRE's were given full YPVS servos.

                      Although you make a good point, the YPVS does shut off at 10'000 rpm as a restriction.

                      But the point here is the build up of NoX's gases. So whilst they did shut off, the normal person would be part throttle anyway. And if you were pinning it, well you would expect it to give up eventually and this might be why.

                      Always Originate, Never Pirate!

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