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  4. DT 125 R '88... New project

DT 125 R '88... New project

Scheduled Pinned Locked Moved DTR
89 Posts 11 Posters 26.1k Views 1 Watching
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  • J Offline
    J Offline
    jgr72
    wrote on last edited by
    #35

    Actually I haven't tried it yet... But it supposed to be a good setup!? Original carb feels a bit out of right setup... It feels rich in mid rev and it won't rev above 8k... top speed is hardly 110km/h. But I have no intention to do anything for it... new carb is only waiting to "step in" 😄

    Still waiting for that oil hose nose from ebay... It's taking many weeks from china to europe sometimes... Meanwhile I had to do something... I drilled a 2.5mm hole for oil feed hose nose and tapped M3 threads with a screw drive style handle... M3 is so small and alu so soft that it was an easy to turn...

    alt text

    alt text

    1 Reply Last reply
    1
    • J Offline
      J Offline
      jgr72
      wrote on last edited by
      #36

      Finally hose noses arrived:

      I bought few of them in case I need one in future...

      alt text

      There it is... I also added some "thread glue":

      alt text

      alt text/20170704_092559.jpg)

      alt text

      Okey, now I have all I need to change the carb. But how about the carb throttle cable? Is it a straight swap, or do I have to make some modifications? I've been trying to find answers from google...

      declanD 1 Reply Last reply
      1
      • J jgr72

        Finally hose noses arrived:

        I bought few of them in case I need one in future...

        alt text

        There it is... I also added some "thread glue":

        alt text

        alt text/20170704_092559.jpg)

        alt text

        Okey, now I have all I need to change the carb. But how about the carb throttle cable? Is it a straight swap, or do I have to make some modifications? I've been trying to find answers from google...

        declanD Offline
        declanD Offline
        declan
        wrote on last edited by
        #37

        @jgr72 it should fit but the only way to know for sure is to actually try it

        1 Reply Last reply
        0
        • CalumC Offline
          CalumC Offline
          Calum
          wrote on last edited by
          #38

          For my dellorto VHSA carb the cable needed modifying.

          Always Originate, Never Pirate!

          1 Reply Last reply
          0
          • J Offline
            J Offline
            jgr72
            wrote on last edited by jgr72
            #39

            Yes, it fits, but I need to strip throttle cable about 30mm... Sorry that my phone focus to the engine, and not the cable 😄 :

            alt text

            But there it is now:

            alt text

            alt text

            TM30 comes quite close to clutch, it can't be installed straight... must be a little bit askew... Maybe some other intake would give better position?:

            alt text

            Next problem is this:

            alt text

            alt text

            It wouldn't line up nice... Maybe DT230 Lanza intake would correct this problem?

            Or then I just make my own boot for universal air filter, and forget the whole original airbox... I tried the bike without air filter and it runs quite nice, no torque loss at low rpm, and still have more power at high rpm... feels good, even I might not have the best jetting setup jet... If I remember right, the best main jet was 135 etc...

            But... I can't ride without an air filter, and I need to fine some solution that I can ride with while I'm planning my next move:

            alt text

            I sprayed urethane, and "glued" 50mm alu pipe to the air box 😄 This wasn't a very professional style, but its easy to remove and airbox is still original, while I don't know what to do next 😄

            CalumC 1 Reply Last reply
            2
            • J jgr72

              Yes, it fits, but I need to strip throttle cable about 30mm... Sorry that my phone focus to the engine, and not the cable 😄 :

              alt text

              But there it is now:

              alt text

              alt text

              TM30 comes quite close to clutch, it can't be installed straight... must be a little bit askew... Maybe some other intake would give better position?:

              alt text

              Next problem is this:

              alt text

              alt text

              It wouldn't line up nice... Maybe DT230 Lanza intake would correct this problem?

              Or then I just make my own boot for universal air filter, and forget the whole original airbox... I tried the bike without air filter and it runs quite nice, no torque loss at low rpm, and still have more power at high rpm... feels good, even I might not have the best jetting setup jet... If I remember right, the best main jet was 135 etc...

              But... I can't ride without an air filter, and I need to fine some solution that I can ride with while I'm planning my next move:

              alt text

              I sprayed urethane, and "glued" 50mm alu pipe to the air box 😄 This wasn't a very professional style, but its easy to remove and airbox is still original, while I don't know what to do next 😄

              CalumC Offline
              CalumC Offline
              Calum
              wrote on last edited by
              #40

              @jgr72 You are running a 3BN barrel.

              They have slightly shorter strokes with bigger bores than the classic 3MB. Be mindful of that when it comes to engine rebuild time.

              Always Originate, Never Pirate!

              1 Reply Last reply
              0
              • J Offline
                J Offline
                jgr72
                wrote on last edited by jgr72
                #41

                Okey, owners manual says that bore is 56mm and stroke 50.7... Does Athena 170cc kit fit into this?

                By the way, someone claims that this bike std carb is 26mm mikuni, here's snap from owners manual, and it clearly says TM28SS:

                alt text

                Isn't TM a flat slide and VM round slide? Carb that I took away, was 28mm round slide! Isn't that a VM28?

                1 Reply Last reply
                0
                • J Offline
                  J Offline
                  jgr72
                  wrote on last edited by
                  #42

                  Now I'm confused, manual of an 3MB page 84 says that 3MB is also 56x50.7:

                  link text

                  1 Reply Last reply
                  0
                  • CalumC Offline
                    CalumC Offline
                    Calum
                    wrote on last edited by
                    #43

                    Again, if your barrel was the 3MB this would be correct.

                    It's not it's the 3BN which I think were off really early DTR's before they swapped the carb for a 28mm and a 3MB barrel.

                    So no, Athena 170 kit is not designed for this engine. You will need to put a 3MB connecting rod, assuming it's just the rod length that's changed, or a 3MB crank.

                    It's not anything big, I just thought I'd mention it incase you wanted to rebuild the engine, it is ever so slightly different.

                    Always Originate, Never Pirate!

                    1 Reply Last reply
                    0
                    • J Offline
                      J Offline
                      jgr72
                      wrote on last edited by
                      #44

                      Okey, barrel have 3BN00 stamp on it... I think I will rebuild it someday... I'll get back then 😄 Hmm... 3MB crank & rod + 3BN piston and barrel would give a little bigger engine 😄

                      CalumC 1 Reply Last reply
                      1
                      • J jgr72

                        Okey, barrel have 3BN00 stamp on it... I think I will rebuild it someday... I'll get back then 😄 Hmm... 3MB crank & rod + 3BN piston and barrel would give a little bigger engine 😄

                        CalumC Offline
                        CalumC Offline
                        Calum
                        wrote on last edited by
                        #45

                        @jgr72 Yeah that was my thought exactly way back way.

                        Approx 133cc if my memory serves me correctly. Or that might have been if it was bored out.

                        I know it's only minor, but you wouldn't want to throw out the characteristics of the engine.

                        I'm pretty sure Yamaha swapped the configuration for a reason.

                        So if it were me, I'd throw a 3MB crank in there and use a 3MB head and barrel.

                        But I have no proof to back this up as beneficial.

                        Always Originate, Never Pirate!

                        1 Reply Last reply
                        0
                        • J Offline
                          J Offline
                          jgr72
                          wrote on last edited by
                          #46

                          Or something bigger? If I have to dismantle whole engine in pieces... why not build up with the biggest available pieces 😛 WR200 or DT200/230 crank, barrel and piston!? I've seen that swap somewhere... Or Athena 170/180cc Its the same job anyway... only some more money to waste 😄

                          declanD CalumC 2 Replies Last reply
                          0
                          • J jgr72

                            Or something bigger? If I have to dismantle whole engine in pieces... why not build up with the biggest available pieces 😛 WR200 or DT200/230 crank, barrel and piston!? I've seen that swap somewhere... Or Athena 170/180cc Its the same job anyway... only some more money to waste 😄

                            declanD Offline
                            declanD Offline
                            declan
                            wrote on last edited by
                            #47

                            @jgr72 id love to have a spare dt to tune

                            1 Reply Last reply
                            0
                            • J jgr72

                              Or something bigger? If I have to dismantle whole engine in pieces... why not build up with the biggest available pieces 😛 WR200 or DT200/230 crank, barrel and piston!? I've seen that swap somewhere... Or Athena 170/180cc Its the same job anyway... only some more money to waste 😄

                              CalumC Offline
                              CalumC Offline
                              Calum
                              wrote on last edited by
                              #48

                              @jgr72 Might as well just swap out the engine when you get to that point.

                              In my opinion, for the bike you currently own. Leave it as original as possible. It's a gorgeous bike in standard trim, any modifications to it is just criminal if you ask me.

                              Always Originate, Never Pirate!

                              declanD J 2 Replies Last reply
                              0
                              • CalumC Calum

                                @jgr72 Might as well just swap out the engine when you get to that point.

                                In my opinion, for the bike you currently own. Leave it as original as possible. It's a gorgeous bike in standard trim, any modifications to it is just criminal if you ask me.

                                declanD Offline
                                declanD Offline
                                declan
                                wrote on last edited by
                                #49

                                @Calum I have a 3mb barrel and a 3bn bottom end what does this mean I don't understand the codes?

                                CalumC 1 Reply Last reply
                                0
                                • declanD declan

                                  @Calum I have a 3mb barrel and a 3bn bottom end what does this mean I don't understand the codes?

                                  CalumC Offline
                                  CalumC Offline
                                  Calum
                                  wrote on last edited by
                                  #50

                                  @declan That's just normal.

                                  Always Originate, Never Pirate!

                                  declanD 1 Reply Last reply
                                  0
                                  • CalumC Calum

                                    @declan That's just normal.

                                    declanD Offline
                                    declanD Offline
                                    declan
                                    wrote on last edited by
                                    #51

                                    @Calum ahh okay thanks

                                    1 Reply Last reply
                                    0
                                    • CalumC Calum

                                      @jgr72 Might as well just swap out the engine when you get to that point.

                                      In my opinion, for the bike you currently own. Leave it as original as possible. It's a gorgeous bike in standard trim, any modifications to it is just criminal if you ask me.

                                      J Offline
                                      J Offline
                                      jgr72
                                      wrote on last edited by
                                      #52

                                      @Calum You're right about keeping this bike original... but since I'm only a human, and I have only one bike that should do all that I want... I will try to keep it look as much original as possible... You simply just can't have too much power... at least this small engine... But to be honest, I can't see very big difference, when accelerating from 0 to 80km/h, when I compare it to my ex XT600... After about 80km/h XT600 would disappear into a horizon...

                                      Is there a inlet that would rise carb a bit? few centimeters would rise it over the clutch thing... And also inlet should have more angle towards to airbox in order to duck around rear shock...

                                      I can't even find inlet bolt pattern... It's not so hard job to do by my self... Or it would be nice to know which inlets would fit direct to 3BN engine... Then I could try to find one from somewhere...

                                      DartyD 1 Reply Last reply
                                      0
                                      • J jgr72

                                        @Calum You're right about keeping this bike original... but since I'm only a human, and I have only one bike that should do all that I want... I will try to keep it look as much original as possible... You simply just can't have too much power... at least this small engine... But to be honest, I can't see very big difference, when accelerating from 0 to 80km/h, when I compare it to my ex XT600... After about 80km/h XT600 would disappear into a horizon...

                                        Is there a inlet that would rise carb a bit? few centimeters would rise it over the clutch thing... And also inlet should have more angle towards to airbox in order to duck around rear shock...

                                        I can't even find inlet bolt pattern... It's not so hard job to do by my self... Or it would be nice to know which inlets would fit direct to 3BN engine... Then I could try to find one from somewhere...

                                        DartyD Offline
                                        DartyD Offline
                                        Darty
                                        wrote on last edited by
                                        #53

                                        @jgr72 There are no direct replacement inlets for a DTR engine.

                                        Believe me I've looked.

                                        Why don't you try modifying a WR200 inlet? They were made for the Mikuni TM30ss...

                                        Keep it real

                                        J 1 Reply Last reply
                                        1
                                        • DartyD Darty

                                          @jgr72 There are no direct replacement inlets for a DTR engine.

                                          Believe me I've looked.

                                          Why don't you try modifying a WR200 inlet? They were made for the Mikuni TM30ss...

                                          J Offline
                                          J Offline
                                          jgr72
                                          wrote on last edited by
                                          #54

                                          @Darty

                                          I will loose inlet bottle with WR200 inlet!? How much does it effect anyway? Have you any idea how much higher carb will be sitting with WR200 inlet?

                                          NINJAN 1 Reply Last reply
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