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    • NINJA
      NINJA last edited by

      I spotted this on ebay and although there are some details in the description, it's still a bit vague. So can anyone more knowledgeable shed some light on it's pro's and con's please ???

      http://www.ebay.co.uk/itm/272944109095?ul_noapp=true

      SEDUCED BY THE DARK SIDE!!!

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      • Calum
        Calum last edited by

        I would get a VHM Head personally mate.

        alt text

        It will describe what piston to use with it.

        pjme.co.uk/acatalog/Aprilia_RS125_Engine_Top_End_.html

        Always Originate, Never Pirate!

        NINJA 1 Reply Last reply Reply Quote 1
        • NINJA
          NINJA @Calum last edited by

          @calum So correct me if I've got this wrong, but after reading the reviews from the PJME link, by swapping the head it will change the compression ratio's, alter the squish band and give better heat transfer over the stock head? Which equates to a higher compression ratio, thus giving more torque, more power and hopefully less detonation by reducing the heat build-up ???

          SEDUCED BY THE DARK SIDE!!!

          declan Calum 2 Replies Last reply Reply Quote 0
          • declan
            declan @NINJA last edited by

            @ninja wouldn’t mind one for the dt

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            • Calum
              Calum @NINJA last edited by

              @ninja No it's not going to be a straight swap no mods.

              My advice is, if you don't want to fannying around with jetting, I would stay well clear. But if you want to maximise the power band, then yeah, this is a treat!

              Go for flat domed piston to close down the squishband, narrowing the powerband.

              Always Originate, Never Pirate!

              NINJA 2 Replies Last reply Reply Quote 0
              • NINJA
                NINJA @Calum last edited by

                @calum So head swap, re-jet and are there any others mods required on top of those ???

                SEDUCED BY THE DARK SIDE!!!

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                • Calum
                  Calum @NINJA last edited by

                  @ninja Base gasket. You'll need to get the squish to the desired dimensons

                  Always Originate, Never Pirate!

                  NINJA 1 Reply Last reply Reply Quote 0
                  • NINJA
                    NINJA @Calum last edited by

                    @calum The thickness of head gasket will determine the correct height for the squish band I take it ???

                    SEDUCED BY THE DARK SIDE!!!

                    Calum 1 Reply Last reply Reply Quote 0
                    • Calum
                      Calum @NINJA last edited by

                      @ninja since you will be using a flat top piston, you will be changing where tdc is in relation to the port tomings. You can use a thicker base gasket to alter this.

                      Always Originate, Never Pirate!

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                      • NINJA
                        NINJA @Calum last edited by

                        @calum said in Billet Head:

                        @ninja No it's not going to be a straight swap no mods.

                        My advice is, if you don't want to fannying around with jetting, I would stay well clear. But if you want to maximise the power band, then yeah, this is a treat!

                        Go for flat domed piston to close down the squishband, narrowing the powerband.

                        Just to clarify should I go for a flat top or domed top piston/head set-up???

                        SEDUCED BY THE DARK SIDE!!!

                        Calum 1 Reply Last reply Reply Quote 0
                        • Calum
                          Calum @NINJA last edited by

                          @ninja What are you after?

                          If you raise the compression, you potentially increase the horsepower, but over a narrower band.

                          You do lose torque mind you.

                          Always Originate, Never Pirate!

                          NINJA 1 Reply Last reply Reply Quote 0
                          • NINJA
                            NINJA @Calum last edited by NINJA

                            @calum My preference would be for more pulling power in the low to mid range for faster acceleration, (Quicker 0-60 & 1/4 mile times), over more top end speed. I would not want to loose any torque, as I would guess that I would need more torque to achieve my goal above.

                            SEDUCED BY THE DARK SIDE!!!

                            Calum 1 Reply Last reply Reply Quote 0
                            • Calum
                              Calum @NINJA last edited by

                              @ninja As a general rule of thumb, the greater the compression ratio the lower torque spread but the greater the peak power. I don't know the figures, but I'd look to go with a domed head.

                              Always Originate, Never Pirate!

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