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DT125R FORUM

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Runs with choke

Scheduled Pinned Locked Moved Engine
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  • OllieDTRO Offline
    OllieDTRO Offline
    OllieDTR
    wrote on last edited by
    #15

    Update:
    Took the carb apart again, checked float height 16mm
    Everything is perfect emulsion tube is missing an o ring, all the kits I see don’t come with one, but on my other dtr carb it has one. Where is best to get a rebuild kit that actually is decent rather than the Chinese cheap stuff? My needle is also bent, what needle code has everyone got?
    Thank you,

    After that if nothing has changed then the left hand side seal has gone already I’m taking it even only being just fitted maybe the cheaper seals don’t last at all

    S 1 Reply Last reply
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    • OllieDTRO OllieDTR

      Update:
      Took the carb apart again, checked float height 16mm
      Everything is perfect emulsion tube is missing an o ring, all the kits I see don’t come with one, but on my other dtr carb it has one. Where is best to get a rebuild kit that actually is decent rather than the Chinese cheap stuff? My needle is also bent, what needle code has everyone got?
      Thank you,

      After that if nothing has changed then the left hand side seal has gone already I’m taking it even only being just fitted maybe the cheaper seals don’t last at all

      S Offline
      S Offline
      SpookDog
      wrote on last edited by
      #16

      @OllieDTR

      None of my carbs have an o-ring fitted to the tube. Just a brass washer under the main jet.
      What size is your pilot?…

      I’ll get needle size posted later when I get back to my shed 🙂 …

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      • OllieDTRO Offline
        OllieDTRO Offline
        OllieDTR
        wrote on last edited by
        #17

        Little update: changed pilot jet from 22.5 all the way to 27.5 and no difference in running without choke, air screw not doing anything, put the needle to the richest possible still nothing, so it’s got to be an air leak only place now is the left hand side crank seal, I’ve replaced them all but they was only eBay ones so could be that, so gone with viton high quality one now.

        What is the float height guys for the TM28ss? It’s at 16mm at the moment
        Thank you

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        • OllieDTRO OllieDTR

          Little update: changed pilot jet from 22.5 all the way to 27.5 and no difference in running without choke, air screw not doing anything, put the needle to the richest possible still nothing, so it’s got to be an air leak only place now is the left hand side crank seal, I’ve replaced them all but they was only eBay ones so could be that, so gone with viton high quality one now.

          What is the float height guys for the TM28ss? It’s at 16mm at the moment
          Thank you

          S Offline
          S Offline
          SpookDog
          wrote on last edited by
          #18

          @OllieDTR

          If it’s your first time fitting them you may of fuxed up the inner spring or not seated them level. I’ve done it myself, more than once. You don’t have to split the cases to replace them…
          I need to reread your thread to see what carb you have fitted. My memory is not wot it used to be 🙂 …

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          • S SpookDog

            @OllieDTR

            If it’s your first time fitting them you may of fuxed up the inner spring or not seated them level. I’ve done it myself, more than once. You don’t have to split the cases to replace them…
            I need to reread your thread to see what carb you have fitted. My memory is not wot it used to be 🙂 …

            S Offline
            S Offline
            SpookDog
            wrote on last edited by SpookDog
            #19

            2004 onwards:

            1DO I.D. mark
            210 main
            17.5 pilot
            5J40 needle 2nd clip from Top
            Q2M (938) emulsion tube
            2.8 throttle slide cutaway
            15.5 ~ 16.5 float height

            You may have an earlier carb though. Check the marks your needle & tube have on them…

            The earlier one is:
            I.D. 3MB00

            210 main
            22.5 pilot
            5J25 needle 4th groove from Top
            Q-2 tube
            2.5 throttle slide cutaway

            Try and suss out what carb you have by the slide cutaway. It’s stamped on it somewhere…

            I may have a needle you can borrow to try swapping out. Let me know the markings on yours & slide…

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            • OllieDTRO Offline
              OllieDTRO Offline
              OllieDTR
              wrote on last edited by
              #20

              Thanks @SpookDog

              My needle is NJ25
              I’ve copied all them settings for my carb and still the same runs good with choke but soon as you turn it off it revs high then dies so definitely a lean state.

              I’ve ordered a viton crank seal now as I bet it’s that. Being cheap quality this one must of some how broke in the process of install.

              As the air screw doesn’t change anything so got to be an airleak there as no where else it could be, as all the other gaskets, are

              OEM from fowlers headgasket
              And the rest of the gaskets are Vertex so decent
              I just ordered a seal kit from eBay for £20 for the lot so that probably explains why the crank seal has gone already lol. These nitrile ones are not strong and no good with fuel I’ve heard.

              Other seal is arriving Tuesday/ Wednesday so I’ll update you then.

              All the best everyone and thank you

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              • OllieDTRO OllieDTR

                Thanks @SpookDog

                My needle is NJ25
                I’ve copied all them settings for my carb and still the same runs good with choke but soon as you turn it off it revs high then dies so definitely a lean state.

                I’ve ordered a viton crank seal now as I bet it’s that. Being cheap quality this one must of some how broke in the process of install.

                As the air screw doesn’t change anything so got to be an airleak there as no where else it could be, as all the other gaskets, are

                OEM from fowlers headgasket
                And the rest of the gaskets are Vertex so decent
                I just ordered a seal kit from eBay for £20 for the lot so that probably explains why the crank seal has gone already lol. These nitrile ones are not strong and no good with fuel I’ve heard.

                Other seal is arriving Tuesday/ Wednesday so I’ll update you then.

                All the best everyone and thank you

                S Offline
                S Offline
                SpookDog
                wrote on last edited by
                #21

                @OllieDTR

                I inadvertently dimpled the side of my seal when I fitted it. I used a flathead screwdriver and was careful, but the contact area you want to hit is only about 1mm of the outermost edge. I only ever use an old seal as a buffer now and use a tube 🙂
                Good luck…

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                • OllieDTRO Offline
                  OllieDTRO Offline
                  OllieDTR
                  wrote on last edited by OllieDTR
                  #22

                  Got the flywheel off this evening and just as we suspected, crank seal failed, lesson learnt! Got new one coming tomorrow

                  Someone’s had a little go before and marked the outside of casing, I drill a little hole, screw a screw in and pull the old seal out. Lucky inside is fine

                  EDIT: when putting new one in i’m going to do what you said @SpookDog use this old one as a “buffer” would you say to put a little oil on the inner so it doesn’t ruin the lip?

                  alt text

                  S 1 Reply Last reply
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                  • OllieDTRO OllieDTR

                    Got the flywheel off this evening and just as we suspected, crank seal failed, lesson learnt! Got new one coming tomorrow

                    Someone’s had a little go before and marked the outside of casing, I drill a little hole, screw a screw in and pull the old seal out. Lucky inside is fine

                    EDIT: when putting new one in i’m going to do what you said @SpookDog use this old one as a “buffer” would you say to put a little oil on the inner so it doesn’t ruin the lip?

                    alt text

                    S Offline
                    S Offline
                    SpookDog
                    wrote on last edited by SpookDog
                    #23

                    @OllieDTR

                    Red rubber grease is the best I recon…

                    Yep, make sure the casing is clean ally, no white oxidation or crud. Then anything that helps it slip in easily. Then push it in with your thumbs. Then gentle, even tapping. It’s so easy to distort the seals ‘face’ and sealing lips 😘
                    Good luck bud! You’ll get there…

                    Just re-looked at the pic. That’s pretty much what happened to me. Hell of a learning curve. I did it to fork seals as well! 🥴 What did you use, a socket, or extension bar?…

                    OllieDTRO 1 Reply Last reply
                    1
                    • S SpookDog

                      @OllieDTR

                      Red rubber grease is the best I recon…

                      Yep, make sure the casing is clean ally, no white oxidation or crud. Then anything that helps it slip in easily. Then push it in with your thumbs. Then gentle, even tapping. It’s so easy to distort the seals ‘face’ and sealing lips 😘
                      Good luck bud! You’ll get there…

                      Just re-looked at the pic. That’s pretty much what happened to me. Hell of a learning curve. I did it to fork seals as well! 🥴 What did you use, a socket, or extension bar?…

                      OllieDTRO Offline
                      OllieDTRO Offline
                      OllieDTR
                      wrote on last edited by
                      #24

                      @SpookDog

                      A socket mate on the edge of the seal but must of not put it in even, I’ve got my old seal now and a tube that slots over so should be smooth sailing..
                      will update you tomorrow 😊

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                      • OllieDTRO OllieDTR

                        @SpookDog

                        A socket mate on the edge of the seal but must of not put it in even, I’ve got my old seal now and a tube that slots over so should be smooth sailing..
                        will update you tomorrow 😊

                        S Offline
                        S Offline
                        SpookDog
                        wrote on last edited by SpookDog
                        #25

                        @OllieDTR

                        I forgot to ask! Did you check your clutch side seal for similar damage? Might as well do it while the doings good, no?…
                        I did most damage to that side on mine! 🥴

                        OllieDTRO 1 Reply Last reply
                        0
                        • S SpookDog

                          @OllieDTR

                          I forgot to ask! Did you check your clutch side seal for similar damage? Might as well do it while the doings good, no?…
                          I did most damage to that side on mine! 🥴

                          OllieDTRO Offline
                          OllieDTRO Offline
                          OllieDTR
                          wrote on last edited by
                          #26

                          @SpookDog

                          Seals arrived today! Didn’t get time to put it in as finished work late and wanted a fresh head on it.
                          Yes I’m going to do both sides, I’ve removed both seals the other day by drilling a small hole in them and then use a screw couple turns and then pull it out.
                          I’ve got with high quality viton seals this time as fuel and high heat resistant 😁

                          Finally can put the bike back together tomorrow! Being the electric start engine that’s 2004+? Correct?

                          So carburettor settings is and correct me if I’m wrong
                          240 main
                          25 pilot
                          4th clip

                          Oh I’ve also ordered a snorkel for the airbox as previous owner decided to remove it but I’ve always found they run better with them in.

                          alt text

                          S 1 Reply Last reply
                          0
                          • OllieDTRO OllieDTR

                            @SpookDog

                            Seals arrived today! Didn’t get time to put it in as finished work late and wanted a fresh head on it.
                            Yes I’m going to do both sides, I’ve removed both seals the other day by drilling a small hole in them and then use a screw couple turns and then pull it out.
                            I’ve got with high quality viton seals this time as fuel and high heat resistant 😁

                            Finally can put the bike back together tomorrow! Being the electric start engine that’s 2004+? Correct?

                            So carburettor settings is and correct me if I’m wrong
                            240 main
                            25 pilot
                            4th clip

                            Oh I’ve also ordered a snorkel for the airbox as previous owner decided to remove it but I’ve always found they run better with them in.

                            alt text

                            S Offline
                            S Offline
                            SpookDog
                            wrote on last edited by
                            #27

                            @OllieDTR

                            Looks good! Yep the needle should be 2nd groove up from the bottom (4 from top) So it could only go one groove higher if wanted…

                            It’ll run like a dream after this bud! 👍 …

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                            • OllieDTRO Offline
                              OllieDTRO Offline
                              OllieDTR
                              wrote on last edited by
                              #28

                              Update:

                              Changed crank seals, no change, so I thought I’d check everything again, cleaned all jets, checked float height and it was 16mm, so I did some research and the float heigh is 20 - 21mm it says in the Haynes anybody got there’s at that?
                              Alittle better but not full fixed, so I thought fresh fuel Abit better again can get it to bog on rev now but will rev past,

                              Thing I’ve ruled it down to now is air…
                              Previous owner cut the airbox, so I’ve ordered a snorkel and what I’m going to do is stick a plastic cover back onto the top of the air box and then cut out a slot with a dremel so the snorkel fits so it’s back to oem, as when you rev it you can hear the mass amount of air being rushed in.

                              I still don’t know why people remove the snorkel and cut the airbox.. Yamaha has probably done so much testing and that is what is best for the flow and feed of air. So I’m 100% certain it’s that as makes sense now runs on choke so that means it’s getting more fuel and when you’ve got more air you’ll need more fuel so choke is the answer.

                              If someone can please let me know on the float height if I’m wrong above thank you !

                              Hopefully it’s here before weekend and then I’ll be back to update you all 😅

                              HOTSHOT IIIH 1 Reply Last reply
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                              • OllieDTRO OllieDTR

                                Update:

                                Changed crank seals, no change, so I thought I’d check everything again, cleaned all jets, checked float height and it was 16mm, so I did some research and the float heigh is 20 - 21mm it says in the Haynes anybody got there’s at that?
                                Alittle better but not full fixed, so I thought fresh fuel Abit better again can get it to bog on rev now but will rev past,

                                Thing I’ve ruled it down to now is air…
                                Previous owner cut the airbox, so I’ve ordered a snorkel and what I’m going to do is stick a plastic cover back onto the top of the air box and then cut out a slot with a dremel so the snorkel fits so it’s back to oem, as when you rev it you can hear the mass amount of air being rushed in.

                                I still don’t know why people remove the snorkel and cut the airbox.. Yamaha has probably done so much testing and that is what is best for the flow and feed of air. So I’m 100% certain it’s that as makes sense now runs on choke so that means it’s getting more fuel and when you’ve got more air you’ll need more fuel so choke is the answer.

                                If someone can please let me know on the float height if I’m wrong above thank you !

                                Hopefully it’s here before weekend and then I’ll be back to update you all 😅

                                HOTSHOT IIIH Offline
                                HOTSHOT IIIH Offline
                                HOTSHOT III
                                wrote on last edited by
                                #29

                                @OllieDTR I've always set the float heights on all my TM28SS carbs to 16mm and never had an issue ('93 3NC, '98 3MB and my '98 3NC on which the carb had been so butchered with silicone sealant down the vent holes etc. I ended up just replacing it with one good carb made of two spares). I read in the TZR125R Yamaha service manual that it's 15.5-16.5mm for that bike where the TM28SS is fitted (UK, France etc.) and I didn't have any other Yamaha service info at the time and so just went with it. The moulding line around the plastic parts of the floats is about parallel with the float bowl gasket face at 16mm and that is usually a good indicator that the float height is about right on most Japanese bike carbs.

                                I'm afraid Haynes never quite got their head around the fact the '88 DTR has a VM26SS carb (same as the original TZR125) and then changed over to the TM28SS flat slide in '89 after one year of production. So various editions of the Haynes manual for the DTR have some pretty big mistakes in the carb section; I think where they specify 20-21mm float height for the TM28SS they got mixed up with the VM26SS, and they list VM26 jet sizes for the TM28 in some parts of the manual, and in others they just say all DTRs have a VM26!

                                It sounds to me like the previous owner has cut a big hole in the top of the airbox "because YZ125" and this is probably what is causing the lean running condition as you say. It's certainly not helping so fixing this and refitting the snorkel before trying anything else is the right approach IMO 👍

                                OllieDTRO 1 Reply Last reply
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                                • HOTSHOT IIIH HOTSHOT III

                                  @OllieDTR I've always set the float heights on all my TM28SS carbs to 16mm and never had an issue ('93 3NC, '98 3MB and my '98 3NC on which the carb had been so butchered with silicone sealant down the vent holes etc. I ended up just replacing it with one good carb made of two spares). I read in the TZR125R Yamaha service manual that it's 15.5-16.5mm for that bike where the TM28SS is fitted (UK, France etc.) and I didn't have any other Yamaha service info at the time and so just went with it. The moulding line around the plastic parts of the floats is about parallel with the float bowl gasket face at 16mm and that is usually a good indicator that the float height is about right on most Japanese bike carbs.

                                  I'm afraid Haynes never quite got their head around the fact the '88 DTR has a VM26SS carb (same as the original TZR125) and then changed over to the TM28SS flat slide in '89 after one year of production. So various editions of the Haynes manual for the DTR have some pretty big mistakes in the carb section; I think where they specify 20-21mm float height for the TM28SS they got mixed up with the VM26SS, and they list VM26 jet sizes for the TM28 in some parts of the manual, and in others they just say all DTRs have a VM26!

                                  It sounds to me like the previous owner has cut a big hole in the top of the airbox "because YZ125" and this is probably what is causing the lean running condition as you say. It's certainly not helping so fixing this and refitting the snorkel before trying anything else is the right approach IMO 👍

                                  OllieDTRO Offline
                                  OllieDTRO Offline
                                  OllieDTR
                                  wrote on last edited by
                                  #30

                                  @HOTSHOT-III

                                  I can always change float height back to 16mm not an issue, I’ve got the snorkel hopefully coming tomorrow so I can patch the airbox up and have the correct amount of air coming in as it should be so can work from there as it’s all guess work without 👍🏻

                                  S 2 Replies Last reply
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                                  • OllieDTRO OllieDTR

                                    @HOTSHOT-III

                                    I can always change float height back to 16mm not an issue, I’ve got the snorkel hopefully coming tomorrow so I can patch the airbox up and have the correct amount of air coming in as it should be so can work from there as it’s all guess work without 👍🏻

                                    S Offline
                                    S Offline
                                    SpookDog
                                    wrote on last edited by SpookDog
                                    #31

                                    @OllieDTR

                                    Off the top of my head it does say 21mm in the Haynes manual, but like @HOTSHOT-III says, they make fux ups all over the place with carbs and wiring diagrams just being ones I’ve had ‘problems’ with 🙂 …

                                    21 sounds like such a big leap for a carb with the same bowl as the other iterations. But, like you said, you can always change it back. I’d try anything if I was in your shoes bud…

                                    1 Reply Last reply
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                                    • OllieDTRO OllieDTR

                                      @HOTSHOT-III

                                      I can always change float height back to 16mm not an issue, I’ve got the snorkel hopefully coming tomorrow so I can patch the airbox up and have the correct amount of air coming in as it should be so can work from there as it’s all guess work without 👍🏻

                                      S Offline
                                      S Offline
                                      SpookDog
                                      wrote on last edited by SpookDog
                                      #32

                                      @OllieDTR

                                      Have you checked the gasket on the carbs slide body? Or the slide top? Anywhere that unmetered air can be getting in? Cracks in the rubber mount even? I personally can’t see the air box being the problem, but it’s a good idea to put every variable back to standard…

                                      If it helps I’d be up to lending you my spare carb to see if swapping it out makes any difference. The jets I have for it are richer, I accidentally opened up the .25 pilot and I only have an aftermarket 250 main for it, but it works…
                                      It’s in Poole…

                                      PS have you got the little tube connecting the power jet from the throttle body to the bowl? If that wasn’t connected it could suck air in there…

                                      OllieDTRO 1 Reply Last reply
                                      1
                                      • CalumC Offline
                                        CalumC Offline
                                        Calum
                                        wrote on last edited by
                                        #33

                                        The airbox on the DTR is pretty restrictive to be fair. Was a common modification by a lot of people tuning their DTRs to cut the entire top section of the airbox off, when these bikes were a dime a dozen.

                                        I purely ran a pod filter on my DTR and am very happy with how it performs. Cutting the box these days seems sacralige but that's just how it was back then.

                                        Either way, when you're diagnosing faults it's always good to go to known working.

                                        Always Originate, Never Pirate!

                                        S 1 Reply Last reply
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                                        • CalumC Calum

                                          The airbox on the DTR is pretty restrictive to be fair. Was a common modification by a lot of people tuning their DTRs to cut the entire top section of the airbox off, when these bikes were a dime a dozen.

                                          I purely ran a pod filter on my DTR and am very happy with how it performs. Cutting the box these days seems sacralige but that's just how it was back then.

                                          Either way, when you're diagnosing faults it's always good to go to known working.

                                          S Offline
                                          S Offline
                                          SpookDog
                                          wrote on last edited by SpookDog
                                          #34

                                          @Calum

                                          The only thing that the pod filter would affect would be the power jet…

                                          Ram Air used to make a kit for the Z1000’s (back at the end of the last century!) they used to supply a drill tap and ‘recalibrated’ screw-in brass jet because it looses some of the ‘suction’ caused by the standard long air intake. Interesting stuff!…

                                          OllieDTRO 1 Reply Last reply
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