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DT125R FORUM

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Dt125 mikuni carb

Scheduled Pinned Locked Moved Carburetor
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  • K kevin

    It’s also worth remembering that carburettors like still air, that’s why the air box is so big, so if you have that strange bottle on the side of the pipe that connects the air box to the carb, it needs blocking as it’s designed to disrupt air flow as a form of restriction.

    Irongamer727I Offline
    Irongamer727I Offline
    Irongamer727
    wrote on last edited by
    #4

    @kevin no it's not restrictive, it's meant to fill up blind spots

    1 Reply Last reply
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    • Irongamer727I Offline
      Irongamer727I Offline
      Irongamer727
      wrote on last edited by
      #5

      Could you link some pilot jets?

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      • K Offline
        K Offline
        kevin
        wrote on last edited by
        #6

        :311670245943 eBay item no.
        No I didn’t mean the yeis bottle I was referring to the other one on the air box side of the carb.

        Irongamer727I 1 Reply Last reply
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        • K kevin

          :311670245943 eBay item no.
          No I didn’t mean the yeis bottle I was referring to the other one on the air box side of the carb.

          Irongamer727I Offline
          Irongamer727I Offline
          Irongamer727
          wrote on last edited by
          #7

          @kevin
          https://imgur.com/gallery/bGFxgyY

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          • Irongamer727I Offline
            Irongamer727I Offline
            Irongamer727
            wrote on last edited by
            #8

            Is is this one?

            K 1 Reply Last reply
            0
            • Irongamer727I Irongamer727

              Is is this one?

              K Offline
              K Offline
              kevin
              wrote on last edited by
              #9

              Yes that’s the one. l would love to see the maths behind it,unfortunately dtpedia.de doesn’t mention it when referring to the vergaser or carburettor as we know it.

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              • Irongamer727I Offline
                Irongamer727I Offline
                Irongamer727
                wrote on last edited by
                #10

                @Calum is it really a restrictor?

                CalumC 1 Reply Last reply
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                • Irongamer727I Irongamer727

                  @Calum is it really a restrictor?

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

                  @irongamer727 Not to my knowledge, the little box on the side of the air box can also be found on the competition bike WR200, they wouldn't restrict a competition bike. At least that's what @AndyYam told me. And he has a lot of experience with all of that.

                  Secondly, the PowerJet, to my knowledge (Happy to be corrected) is a clever mechanism to lean the fuel off at wide open throttle, when actually you don't need as much fuel.

                  The logic is that at WOT, you should be easing off the load of the engine and now it's all about refining that combustible mix. The leaner you can run that engine, the better the burn of combustible mix can be.

                  The trick is to lean it off as much as possible, without causing detonation.

                  Always Originate, Never Pirate!

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                  • Glynn123G Offline
                    Glynn123G Offline
                    Glynn123
                    wrote on last edited by
                    #12

                    Removed that little airbox bottle on mine, can't say I noticed any difference but bike runs strong with pleanty pull with it removed and plugged.

                    CalumC 1 Reply Last reply
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                    • Glynn123G Glynn123

                      Removed that little airbox bottle on mine, can't say I noticed any difference but bike runs strong with pleanty pull with it removed and plugged.

                      CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #13

                      @glynn123 There are better ways to restrict the bike than some plastic box on the inlet tract lol.

                      I don't know the science behind it, I figured it would work in a similar fashion to the YEIS. But it's as mystery.

                      The DTRE also had YAIS as well.

                      Always Originate, Never Pirate!

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                      • Irongamer727I Offline
                        Irongamer727I Offline
                        Irongamer727
                        wrote on last edited by
                        #14

                        My Haynes manual says stock pilot jet fit the Dtx is 17.5? What the hell? Thought it was 25.

                        K 1 Reply Last reply
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                        • Irongamer727I Irongamer727

                          My Haynes manual says stock pilot jet fit the Dtx is 17.5? What the hell? Thought it was 25.

                          K Offline
                          K Offline
                          kevin
                          wrote on last edited by
                          #15

                          @irongamer727 first flatslides came with 22.5 and later models 17.5 and 210 mainjet

                          Irongamer727I 1 Reply Last reply
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                          • K kevin

                            @irongamer727 first flatslides came with 22.5 and later models 17.5 and 210 mainjet

                            Irongamer727I Offline
                            Irongamer727I Offline
                            Irongamer727
                            wrote on last edited by
                            #16

                            @kevin Alright, thx

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                            • Irongamer727I Offline
                              Irongamer727I Offline
                              Irongamer727
                              wrote on last edited by
                              #17

                              So I was finally able to unscrew my pilot jet for my dtx. It is a nightmare to start now with the Athena kit. I looked in the Haynes manual and it claimed stock pilot jet for the dtx was 17.5.
                              Mine was a 35! What on earth? How is it possible it is hard to start NOW and not when it was 100% stock?

                              Pilot jet size 35 https://imgur.com/gallery/fS02dV8

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                              • Irongamer727I Offline
                                Irongamer727I Offline
                                Irongamer727
                                wrote on last edited by
                                #18

                                Either way, it is too big right?

                                1 Reply Last reply
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                                • Irongamer727I Offline
                                  Irongamer727I Offline
                                  Irongamer727
                                  wrote on last edited by
                                  #19

                                  Response please...

                                  K 1 Reply Last reply
                                  0
                                  • CalumC Offline
                                    CalumC Offline
                                    Calum
                                    wrote on last edited by
                                    #20

                                    Ask any tuner how to set up a carburettor and you'll get the same response.

                                    It depends on your setup.

                                    Everything from Atmospheric conditions to state of the engine and even altitude will affect jetting.

                                    It's imperative that ones carb is tuned to these varying conditions.

                                    20 years ago, Yamaha spent thousands on designing the perfect carburettor settings to get the DT roughly in the right ball park.

                                    The moment you started modifying the bike, you throw all of Yamaha's hard work out the window.

                                    Just because it had some ridiculous settings on it, doesn't necessarily mean it was wrong.

                                    Jetting should be done to suit, and there is reams of guides on here to help you get the bike in right area.

                                    Always Originate, Never Pirate!

                                    Irongamer727I 1 Reply Last reply
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                                    • CalumC Calum

                                      Ask any tuner how to set up a carburettor and you'll get the same response.

                                      It depends on your setup.

                                      Everything from Atmospheric conditions to state of the engine and even altitude will affect jetting.

                                      It's imperative that ones carb is tuned to these varying conditions.

                                      20 years ago, Yamaha spent thousands on designing the perfect carburettor settings to get the DT roughly in the right ball park.

                                      The moment you started modifying the bike, you throw all of Yamaha's hard work out the window.

                                      Just because it had some ridiculous settings on it, doesn't necessarily mean it was wrong.

                                      Jetting should be done to suit, and there is reams of guides on here to help you get the bike in right area.

                                      Irongamer727I Offline
                                      Irongamer727I Offline
                                      Irongamer727
                                      wrote on last edited by
                                      #21

                                      @calum guess so. Only way is to buy and try stuff I guess

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                                      • Irongamer727I Irongamer727

                                        Response please...

                                        K Offline
                                        K Offline
                                        kevin
                                        wrote on last edited by
                                        #22

                                        @irongamer727 I’m a firm believer in leaving things the way they are and not thinking I’m better than the designers.
                                        To answer your question 35 is very big for your carb.
                                        Does Athena give any tips on resetting.
                                        You say it’s hard to start, have you checked the fuel feed pipe when the cold start lever is on as it’s very narrow and often gets blocked.

                                        Irongamer727I 1 Reply Last reply
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                                        • K kevin

                                          @irongamer727 I’m a firm believer in leaving things the way they are and not thinking I’m better than the designers.
                                          To answer your question 35 is very big for your carb.
                                          Does Athena give any tips on resetting.
                                          You say it’s hard to start, have you checked the fuel feed pipe when the cold start lever is on as it’s very narrow and often gets blocked.

                                          Irongamer727I Offline
                                          Irongamer727I Offline
                                          Irongamer727
                                          wrote on last edited by
                                          #23

                                          @kevin nope. Athena don't give any recommendations at all. Do you mean the fuel hose itself? That's brand new. The choke works, could there be some debris in the mechanism you think?

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