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DT125R FORUM

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  3. Engine
  4. Gearbox failure

Gearbox failure

Scheduled Pinned Locked Moved Engine
27 Posts 7 Posters 2.2k Views 1 Watching
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  • L Offline
    L Offline
    lllDennis
    wrote on last edited by
    #18
    This post is deleted!
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    • T theportingmaster

      @lllDennis Two-stroke piston seizures are either thermal-related or lubrication-failure-related. That one appears to me to be lubrication in nature. Could be overly rich jetting that allowed liquid fuel to wash oil off of the piston skirt as the fuel comes through the transfer ports, causing a lubrication failure.
      If you need a gearbox have a couple of complete low mileage boxes can do you cheap.

      L Offline
      L Offline
      lllDennis
      wrote on last edited by
      #19

      @theportingmaster The jetting was extremely rich. Apparently there are 2 sorts of mikuni jet 'sizes'. In my carb there was a 250 mikuni jet. So i ordered aftermarket 250-300 for the Athena kit to test with. But the aftermarket 180 size is the same as original 250.

      It was overlay rich while tuning the carb until i figured this out.

      If you got a excellent low milage gearbox for me send me a message with some details. Really appreciate it 👌
      I looked at new original parts but it's a little expensive for my student wallet 😂

      CalumC 1 Reply Last reply
      0
      • L lllDennis

        @theportingmaster The jetting was extremely rich. Apparently there are 2 sorts of mikuni jet 'sizes'. In my carb there was a 250 mikuni jet. So i ordered aftermarket 250-300 for the Athena kit to test with. But the aftermarket 180 size is the same as original 250.

        It was overlay rich while tuning the carb until i figured this out.

        If you got a excellent low milage gearbox for me send me a message with some details. Really appreciate it 👌
        I looked at new original parts but it's a little expensive for my student wallet 😂

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

        @llldennis dayum, that's not a stripped gear, that's completely melted

        Always Originate, Never Pirate!

        L 1 Reply Last reply
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        • T Offline
          T Offline
          theportingmaster
          wrote on last edited by
          #21

          @lllDennis Best jetting for Athena 170 is 300 main jet on the
          Mikuni tm28 but with the powerjet blocked off. Just cut the
          rubber tube in half from the float chamber to the powerjet then block the 2 halves of the rubber tube with a couple of 5mm threaded bolts or similar.

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          • CalumC Calum

            @llldennis dayum, that's not a stripped gear, that's completely melted

            L Offline
            L Offline
            lllDennis
            wrote on last edited by lllDennis
            #22

            @calum Any recommendations on a crankshaft? While everything is open I want to replace it anyway (Has some small grooves where the bearing is). Best with original or aftermarket?

            CalumC 1 Reply Last reply
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            • L lllDennis

              @calum Any recommendations on a crankshaft? While everything is open I want to replace it anyway (Has some small grooves where the bearing is). Best with original or aftermarket?

              CalumC Online
              CalumC Online
              Calum
              wrote on last edited by
              #23

              @llldennis Didn't know they do aftermarket cranks?

              Always Originate, Never Pirate!

              NottsbikerN jimmydc98J 2 Replies Last reply
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              • CalumC Calum

                @llldennis Didn't know they do aftermarket cranks?

                NottsbikerN Offline
                NottsbikerN Offline
                Nottsbiker
                wrote on last edited by
                #24

                @calum

                There's some on ebay for less than £200

                jimmydc98J 1 Reply Last reply
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                • CalumC Calum

                  @llldennis Didn't know they do aftermarket cranks?

                  jimmydc98J Offline
                  jimmydc98J Offline
                  jimmydc98
                  wrote on last edited by
                  #25

                  @calum pretty sure they sell the aftermarket cranks on PJME as well

                  DT200WR 1997 - New Project
                  DTR 125 1997 - The Bike That Got Stolen
                  DTR 125 2002 - Project
                  DT 125 LC 1986 - Old Bike

                  1 Reply Last reply
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                  • NottsbikerN Nottsbiker

                    @calum

                    There's some on ebay for less than £200

                    jimmydc98J Offline
                    jimmydc98J Offline
                    jimmydc98
                    wrote on last edited by
                    #26

                    @nottsbiker https://www.pjme.co.uk/acatalog/Yamaha-DT125R-Complete-Crankshaft-Top-Racing--4596.html#SID=103

                    DT200WR 1997 - New Project
                    DTR 125 1997 - The Bike That Got Stolen
                    DTR 125 2002 - Project
                    DT 125 LC 1986 - Old Bike

                    CalumC 1 Reply Last reply
                    0
                    • jimmydc98J jimmydc98

                      @nottsbiker https://www.pjme.co.uk/acatalog/Yamaha-DT125R-Complete-Crankshaft-Top-Racing--4596.html#SID=103

                      CalumC Online
                      CalumC Online
                      Calum
                      wrote on last edited by
                      #27

                      @jimmydc98 Cheap 😍

                      That's good to know at least. Connecting Rod for my RS is that price alone 😛

                      Always Originate, Never Pirate!

                      1 Reply Last reply
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