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DT125R FORUM

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  4. The Helios Project (Aprilia RS 125 Rotax 122 Biaggi Race Replica)

The Helios Project (Aprilia RS 125 Rotax 122 Biaggi Race Replica)

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  • NINJAN NINJA

    @calum The Magura clutches are expensive, but apart from the cheap Chinese ones on ebay, there's not a lot else too choose from. I want one on my MX for-sure, can you post a link to the thread you found detailing the hydro conversion please???

    CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #100

    @ninja You won't like it, lol. It was using PhotoFuckit and all the photos are messed up.

    I'll have this one done by the end of the week.

    Here is how Honda did it

    alt text
    alt text

    They've used the original clutch actuation for it.

    Here is the thread.

    http://www.125ccsportsbikes.com/forums/index.php?showtopic=100907

    Always Originate, Never Pirate!

    NINJAN 1 Reply Last reply
    1
    • CalumC Calum

      @ninja You won't like it, lol. It was using PhotoFuckit and all the photos are messed up.

      I'll have this one done by the end of the week.

      Here is how Honda did it

      alt text
      alt text

      They've used the original clutch actuation for it.

      Here is the thread.

      http://www.125ccsportsbikes.com/forums/index.php?showtopic=100907

      NINJAN Offline
      NINJAN Offline
      NINJA
      wrote on last edited by
      #101

      @calum OK Thanks, perhaps if you have the time you could post a tutorial on how to do it and the parts needed etc. please. 😉

      SEDUCED BY THE DARK SIDE!!!

      CalumC 1 Reply Last reply
      0
      • NINJAN NINJA

        @calum OK Thanks, perhaps if you have the time you could post a tutorial on how to do it and the parts needed etc. please. 😉

        CalumC Offline
        CalumC Offline
        Calum
        wrote on last edited by
        #102

        @ninja I plan to 😄

        Always Originate, Never Pirate!

        NINJAN 1 Reply Last reply
        1
        • CalumC Calum

          @ninja I plan to 😄

          NINJAN Offline
          NINJAN Offline
          NINJA
          wrote on last edited by
          #103

          @calum COOL Thanks, does either bike have the choke/hot start lever incorporated in the overall clutch lever/mount???

          SEDUCED BY THE DARK SIDE!!!

          CalumC 1 Reply Last reply
          0
          • NINJAN NINJA

            @calum COOL Thanks, does either bike have the choke/hot start lever incorporated in the overall clutch lever/mount???

            CalumC Offline
            CalumC Offline
            Calum
            wrote on last edited by
            #104

            @ninja Built into the left hand controls.

            Always Originate, Never Pirate!

            1 Reply Last reply
            0
            • NINJAN Offline
              NINJAN Offline
              NINJA
              wrote on last edited by NINJA
              #105

              I want a SuMo one;

              https://www.youtube.com/watch?v=Nxxasvsbe_Y

              SEDUCED BY THE DARK SIDE!!!

              CalumC 1 Reply Last reply
              1
              • NINJAN NINJA

                I want a SuMo one;

                https://www.youtube.com/watch?v=Nxxasvsbe_Y

                CalumC Offline
                CalumC Offline
                Calum
                wrote on last edited by
                #106

                @ninja I know mate, but you got to import them and by which time they are really expensive.

                Always Originate, Never Pirate!

                NINJAN 1 Reply Last reply
                0
                • CalumC Calum

                  @ninja I know mate, but you got to import them and by which time they are really expensive.

                  NINJAN Offline
                  NINJAN Offline
                  NINJA
                  wrote on last edited by
                  #107

                  @calum True but isn't owning rare gems every enthusiast's dreams???

                  SEDUCED BY THE DARK SIDE!!!

                  CalumC 1 Reply Last reply
                  0
                  • NINJAN NINJA

                    @calum True but isn't owning rare gems every enthusiast's dreams???

                    CalumC Offline
                    CalumC Offline
                    Calum
                    wrote on last edited by
                    #108

                    @ninja I think, for the money, you could have a supermoto Honda CR500.

                    So it's kinda like, well they're rarer and better.

                    Always Originate, Never Pirate!

                    1 Reply Last reply
                    0
                    • CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by Calum
                      #109

                      So this arrived this morning.

                      alt text

                      It's the Italkit Gilardoni 140cc cylinder kit for the Rotax 122 engine.

                      I feel like a bit of history is needed to really appreciate this cylinder.

                      Gilardoni is the original designer of the Rotax 122 cylinder way back when.

                      alt text

                      Original Barrel for reference

                      A few years ago he revises the cylinder in the form of this cylinder. This cylinder reflects lessons learnt over all of the years people have been racing these engines. All of this is reflected in the barrels design.

                      alt text

                      alt text

                      Now I was tossing and turning trying to decide what route to take with this engine. Initially, sticking with the Gilardoni Rotax 122 original cylinder, opting to have it ported to reflect my systems designed.

                      But no matter what engine I bought, the cylinders were all scrap,and it was going to cost £300 to remanufacture the cylinder to usable condition.

                      I have ridden Aprilia RS 125's since I was 16, that's a little under a decade of riding experience on these engines alone. I have ridden bad ones and I've ridden good ones. I've ridden bog standard ones, and highly tuned ones.

                      The thing that stuck in my mind the most is how the original engine revs to 14K, and I always appreciated that out of the original cylinder.

                      When riding Polini's 160cc kit, you lose around 2K over rev. This isn't the case with this barrel. It'll continue to pull hard to 14k, granted it's not the extra CC's that give you the bang.

                      The porting work on this engine is superfluous, it's extremely well done for a casted material.

                      alt text
                      alt text

                      Sure there are further refinements that could be done here, a few edges taken off and some minor flaws altered, but on the whole, it's a very well designed cylinder.

                      Combine this with PJME's Reworked VHM billet head, and you have yourself a very capable top end.

                      alt text

                      The cylinder is running a relatively high 12.1:1 compression ratio, less than ideal for reliable road use. The fueling on this cylinder needs to be finely tuned to avoid running the risk of detonation. This engine must be run on Shell Super Unleaded, else it's just going to detonate.

                      alt text

                      All this power is no good if you can't stop for the corners.

                      alt text

                      I've ran these on my DT, with the older style Aprilia braking system. So running this on the radials will surely surprise me.

                      These Brembo Sintered brakes are £40 a pop, if you can find a set. Were sold out everyone I looked.

                      I refurbished the brakes themselves back in Christmas time, and I've just ordered titanium retainer pins and titanium bolts to fix it to the forks.

                      alt text

                      alt text

                      So far so good.

                      I need to calculate the squish on the engine I'm building to ensure I get the right compression ratio, then drop the engine into the frame.

                      I need to order some titanium head bolts, V-Force3 Reed cage and 34mm inlet. The dellorto racing carburettor has been ordered. Some £1000 spent this month already, with more to follow...

                      Always Originate, Never Pirate!

                      declanD 1 Reply Last reply
                      0
                      • CalumC Calum

                        So this arrived this morning.

                        alt text

                        It's the Italkit Gilardoni 140cc cylinder kit for the Rotax 122 engine.

                        I feel like a bit of history is needed to really appreciate this cylinder.

                        Gilardoni is the original designer of the Rotax 122 cylinder way back when.

                        alt text

                        Original Barrel for reference

                        A few years ago he revises the cylinder in the form of this cylinder. This cylinder reflects lessons learnt over all of the years people have been racing these engines. All of this is reflected in the barrels design.

                        alt text

                        alt text

                        Now I was tossing and turning trying to decide what route to take with this engine. Initially, sticking with the Gilardoni Rotax 122 original cylinder, opting to have it ported to reflect my systems designed.

                        But no matter what engine I bought, the cylinders were all scrap,and it was going to cost £300 to remanufacture the cylinder to usable condition.

                        I have ridden Aprilia RS 125's since I was 16, that's a little under a decade of riding experience on these engines alone. I have ridden bad ones and I've ridden good ones. I've ridden bog standard ones, and highly tuned ones.

                        The thing that stuck in my mind the most is how the original engine revs to 14K, and I always appreciated that out of the original cylinder.

                        When riding Polini's 160cc kit, you lose around 2K over rev. This isn't the case with this barrel. It'll continue to pull hard to 14k, granted it's not the extra CC's that give you the bang.

                        The porting work on this engine is superfluous, it's extremely well done for a casted material.

                        alt text
                        alt text

                        Sure there are further refinements that could be done here, a few edges taken off and some minor flaws altered, but on the whole, it's a very well designed cylinder.

                        Combine this with PJME's Reworked VHM billet head, and you have yourself a very capable top end.

                        alt text

                        The cylinder is running a relatively high 12.1:1 compression ratio, less than ideal for reliable road use. The fueling on this cylinder needs to be finely tuned to avoid running the risk of detonation. This engine must be run on Shell Super Unleaded, else it's just going to detonate.

                        alt text

                        All this power is no good if you can't stop for the corners.

                        alt text

                        I've ran these on my DT, with the older style Aprilia braking system. So running this on the radials will surely surprise me.

                        These Brembo Sintered brakes are £40 a pop, if you can find a set. Were sold out everyone I looked.

                        I refurbished the brakes themselves back in Christmas time, and I've just ordered titanium retainer pins and titanium bolts to fix it to the forks.

                        alt text

                        alt text

                        So far so good.

                        I need to calculate the squish on the engine I'm building to ensure I get the right compression ratio, then drop the engine into the frame.

                        I need to order some titanium head bolts, V-Force3 Reed cage and 34mm inlet. The dellorto racing carburettor has been ordered. Some £1000 spent this month already, with more to follow...

                        declanD Offline
                        declanD Offline
                        declan
                        wrote on last edited by
                        #110

                        @calum im expecting the very first attempt to start the bike on here 🤤

                        CalumC 1 Reply Last reply
                        0
                        • declanD declan

                          @calum im expecting the very first attempt to start the bike on here 🤤

                          CalumC Offline
                          CalumC Offline
                          Calum
                          wrote on last edited by
                          #111

                          @declan Yeah I'll get a video up when that happens don't you worry 😄

                          I'm still probably another payday off yet.

                          Needs CDI (Zeeltronic), indicators, wing mirrors and a good number of other electronics.

                          I've got the radiator now and hoses.

                          I expect there is going to be the odd bit here and there left to do.

                          Fairings have been ordered. They are made to order so they take ten days plus shipping.

                          And then there are the custom fabriacted bits, plus a little more painting that needs doing.

                          Should have it dyno'd towards the later end of the summer, see what she's making.

                          Always Originate, Never Pirate!

                          1 Reply Last reply
                          0
                          • Irongamer727I Offline
                            Irongamer727I Offline
                            Irongamer727
                            wrote on last edited by
                            #112

                            The compassion ratio on my Athena is supposedly 13:1. And yours 12:1:1? What's the difference? Cool stuff you got there!

                            CalumC 1 Reply Last reply
                            0
                            • Irongamer727I Irongamer727

                              The compassion ratio on my Athena is supposedly 13:1. And yours 12:1:1? What's the difference? Cool stuff you got there!

                              CalumC Offline
                              CalumC Offline
                              Calum
                              wrote on last edited by Calum
                              #113

                              @irongamer727 That's savagely highly.

                              The stock DT is 8:1 lol.

                              The higher the CR, in general, the more extremely the powerband and the less torque.

                              I'd be very surprised if the somewhat powerless Athena kit is 13:1. You can have too much which has adverse affects.

                              I'd be more inclined to say the Athena is a lot lower, as it's generally a more torquey setup.

                              The higher the CR the more...unreliable an engine becomes. A lot of stresses on the bottom end and components you see.

                              Always Originate, Never Pirate!

                              Irongamer727I 1 Reply Last reply
                              0
                              • CalumC Calum

                                @irongamer727 That's savagely highly.

                                The stock DT is 8:1 lol.

                                The higher the CR, in general, the more extremely the powerband and the less torque.

                                I'd be very surprised if the somewhat powerless Athena kit is 13:1. You can have too much which has adverse affects.

                                I'd be more inclined to say the Athena is a lot lower, as it's generally a more torquey setup.

                                The higher the CR the more...unreliable an engine becomes. A lot of stresses on the bottom end and components you see.

                                Irongamer727I Offline
                                Irongamer727I Offline
                                Irongamer727
                                wrote on last edited by
                                #114

                                @calum http://www.rrd-preparation.com/en/kit-high-engine-motor-bike-125cc-2-time/671-kit-170cc-athena-moteur-125cc-derbi-gpr-yamaha-tdr-dt-tzr-2-temps.html

                                Here's where I got the info.

                                1 Reply Last reply
                                0
                                • Irongamer727I Offline
                                  Irongamer727I Offline
                                  Irongamer727
                                  wrote on last edited by
                                  #115

                                  http://www.athenaparts.com/eng/kits/view/7483/cylinder-kit-with-head-170-cc

                                  The data sheet says 13:2:1. No clue if that's the same as 13:1

                                  CalumC 1 Reply Last reply
                                  0
                                  • Irongamer727I Irongamer727

                                    http://www.athenaparts.com/eng/kits/view/7483/cylinder-kit-with-head-170-cc

                                    The data sheet says 13:2:1. No clue if that's the same as 13:1

                                    CalumC Offline
                                    CalumC Offline
                                    Calum
                                    wrote on last edited by
                                    #116

                                    @irongamer727 I don't know. But 13:1 is very high

                                    Always Originate, Never Pirate!

                                    1 Reply Last reply
                                    0
                                    • D Offline
                                      D Offline
                                      DTR+NSR
                                      wrote on last edited by
                                      #117

                                      Those compression ratio's are both probably un corrected values, hence so high. The 'true' or corrected CR is worked out from the stroke once the piston has covered the ports, when your truly compressing the mixture. Not from bdc.

                                      CalumC 1 Reply Last reply
                                      1
                                      • D DTR+NSR

                                        Those compression ratio's are both probably un corrected values, hence so high. The 'true' or corrected CR is worked out from the stroke once the piston has covered the ports, when your truly compressing the mixture. Not from bdc.

                                        CalumC Offline
                                        CalumC Offline
                                        Calum
                                        wrote on last edited by
                                        #118

                                        @dtr-nsr Yes that would make sense.

                                        The Aprilia barrel's transfer ports, like the KTM, are incredibly low in the barrel. The Athena barrels are relatively high by comparison.

                                        Always Originate, Never Pirate!

                                        1 Reply Last reply
                                        0
                                        • J Offline
                                          J Offline
                                          Jens Eskildsen
                                          wrote on last edited by
                                          #119

                                          Generally, higher CR gives more torque, and a better powerband, not the other way around. Otherwise they would surely reduce the CR on endurobikes compared to their MX rivals, to give them broader powerband, but they dont...

                                          "A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency"

                                          This pic from the book "basic 2 stroke tuning":
                                          0_1525368861786_torque.png

                                          1 Reply Last reply
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