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DT125R FORUM

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Time to change wheels and ...

Scheduled Pinned Locked Moved Top End
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  • declanD declan

    @calum how much did that cost bud and can it just bolt back on no jet changes etc

    CalumC Online
    CalumC Online
    Calum
    wrote on last edited by
    #26

    @declan No, porting is going to drastically change the characteristics of a two stroke engine.

    I wouldn't advise it on a daily, or on stock ignition.

    You don't get something for nothing. I'm not going into it here, but the principle is, peak almost always alters performance elsewhere, usually torque.

    There are exceptions where engines are poorly designed and modifications improve performance with no effect. But the end of it is, these engines are pretty well designed. When it comes to porting them, you're making a sacrafice somewhere else in the rev range for more power.

    Always Originate, Never Pirate!

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    1
    • Y Offline
      Y Offline
      Yegor
      wrote on last edited by
      #27

      Hello ) !
      I will go tomorrow to the workshop with the cylinder for bore. I know is privileged information and long testing time but do you know where I can find information about tuning cylinder transfers, I think is good idea do something there before it will be bored. Maybe in the same workshop they do that for extra €, will ask.

      all this marked with color dots can be modified/enlarged : ?
      0_1513007430177_cilindro marcado.jpg
      at the top of ALL the transfers: (?)
      0_1513007813829_IMG_20171205_163907.jpg

      so, thank you again for the help, and gas gas !

      1 Reply Last reply
      0
      • CalumC Online
        CalumC Online
        Calum
        wrote on last edited by
        #28

        Depending on how good your English reading is, I HIGHLY recommend Graham Bell's Two Stroke Performance Tuning.

        That will give you a lot of knowledge on tuning two strokes.

        I would NOT recommend porting the barrel, or altering the port timings, without a programmable CDI.

        Always Originate, Never Pirate!

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        • Y Offline
          Y Offline
          Yegor
          wrote on last edited by Yegor
          #29

          @calum said in Time to change wheels and ...:

          Graham Bell's Two Stroke Performance Tuning

          Thanks for the tip Calum . also I have dowloaded the Two-Stroke TUNER'S HANDBOOK By Gordon Jennings. Time to read.
          ( http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php )

          so, for now I'm going to polish a little bit where it is needed , also the power valve , because it is very dirty.
          Mitaka pistons are good ? where you can buy original Yamaha DT R parts online ( like water pump complete repair kit) ? <--- have find this official site : http://www.recambios-yamaha.com/es/dt125r/2002/bomba-de-agua.html

          Thank you very much everyone, your answers are very useful.

          CalumC 1 Reply Last reply
          0
          • Y Yegor

            @calum said in Time to change wheels and ...:

            Graham Bell's Two Stroke Performance Tuning

            Thanks for the tip Calum . also I have dowloaded the Two-Stroke TUNER'S HANDBOOK By Gordon Jennings. Time to read.
            ( http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php )

            so, for now I'm going to polish a little bit where it is needed , also the power valve , because it is very dirty.
            Mitaka pistons are good ? where you can buy original Yamaha DT R parts online ( like water pump complete repair kit) ? <--- have find this official site : http://www.recambios-yamaha.com/es/dt125r/2002/bomba-de-agua.html

            Thank you very much everyone, your answers are very useful.

            CalumC Online
            CalumC Online
            Calum
            wrote on last edited by
            #30

            @yegor I'd recommend PJME, they're based in England but are Two Stroke Specialist, I believe they ship world wide.

            Polishing will get you so far, gasket matching is going to be far more effective.

            If you're going for performance, I'd avoid mitaka. Nothing wrong with them, but they are cheap CAST pistons designed to offer a cheap alternative to OEM.

            For performance, go forged. Grab yourself a forged Wiesco piston and a set of chromium rings.

            Always Originate, Never Pirate!

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            • Y Offline
              Y Offline
              Yegor
              wrote on last edited by
              #31

              @calum said in Time to change wheels and ...:

              Grab yourself a forged Wiesco piston and a set of chromium rings.

              can't find Wiseco ( one ring ?) piston for my model. But in PJME I have find Wossner piston ( 2 rings) , they are good I think, also forged (?)

              Do you know if in PJME there Wiseco piston for the DT R ?

              waiting answer from this site . http://www.paramimoto.com/pistones/343-wiseco-piston-yamaha-2-tiempos.html#/piston-dt_125_75_76_684m05600

              CalumC 1 Reply Last reply
              0
              • Y Yegor

                @calum said in Time to change wheels and ...:

                Grab yourself a forged Wiesco piston and a set of chromium rings.

                can't find Wiseco ( one ring ?) piston for my model. But in PJME I have find Wossner piston ( 2 rings) , they are good I think, also forged (?)

                Do you know if in PJME there Wiseco piston for the DT R ?

                waiting answer from this site . http://www.paramimoto.com/pistones/343-wiseco-piston-yamaha-2-tiempos.html#/piston-dt_125_75_76_684m05600

                CalumC Online
                CalumC Online
                Calum
                wrote on last edited by
                #32

                @yegor Ahh yeah sorry mate, vertex and Wossner are perfectly good forged components, I run Wossner myself, but will be switiching to wiseco for my new engine I'm building.

                For reliability, I'd stick to twin rings rather than just one.

                Always Originate, Never Pirate!

                1 Reply Last reply
                0
                • Y Offline
                  Y Offline
                  Yegor
                  wrote on last edited by Yegor
                  #33

                  Hello friends !

                  Finnaly I've recived the piston. While they still fix the cylinder, I am reading carburation manuals and cleaning the Mikuni. I'll buy carburetor jet kit from 180 to 250.

                  I have noticed that the Yamaha piston rings are different while the Wossner ones are the same:
                  0_1514472080448_26177755_10214388893254589_184702224_o.jpg

                  The Small End Bearing is 17mm ( the one that was put ) but the original bearing for Yamaha piston is 19.5 mm, so is very important replace it ?
                  0_1514472465753_26179304_10214388983376842_1813155606_o.jpg

                  And I see that the Wossner piston does not have holes that lubricate the gudgeon pin:
                  0_1514472779932_26237588_10214388991897055_396085839_o.jpg

                  ( it might be a good idea to do them? although I do not think so ) )

                  I have a base gasket but the Genuine Base Gasket it is made of metal (aluminium?) , so It is highly recommended put the metal one ?

                  uf a lot of questions but thank you in advance . :man_biking_tone1:

                  declanD 1 Reply Last reply
                  0
                  • Y Yegor

                    Hello friends !

                    Finnaly I've recived the piston. While they still fix the cylinder, I am reading carburation manuals and cleaning the Mikuni. I'll buy carburetor jet kit from 180 to 250.

                    I have noticed that the Yamaha piston rings are different while the Wossner ones are the same:
                    0_1514472080448_26177755_10214388893254589_184702224_o.jpg

                    The Small End Bearing is 17mm ( the one that was put ) but the original bearing for Yamaha piston is 19.5 mm, so is very important replace it ?
                    0_1514472465753_26179304_10214388983376842_1813155606_o.jpg

                    And I see that the Wossner piston does not have holes that lubricate the gudgeon pin:
                    0_1514472779932_26237588_10214388991897055_396085839_o.jpg

                    ( it might be a good idea to do them? although I do not think so ) )

                    I have a base gasket but the Genuine Base Gasket it is made of metal (aluminium?) , so It is highly recommended put the metal one ?

                    uf a lot of questions but thank you in advance . :man_biking_tone1:

                    declanD Offline
                    declanD Offline
                    declan
                    wrote on last edited by
                    #34

                    @yegor as far as I know stock bikes don’t have the metal base gasket I wouldn’t bother with the lubrication hole if it was needed they would of already done it

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                    • CalumC Online
                      CalumC Online
                      Calum
                      wrote on last edited by
                      #35

                      OEM gaskets are far superior, but Athena gaskets are perfectly good. You MUST use either genuine or Athena for the head gasket. The base gasket doesn't matter.

                      Be sure to measure the piston ring end gaps on those wossner rings. I have never had a set that were perfect, they've always needed fettling.

                      Always Originate, Never Pirate!

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                      0
                      • terry.tzT Offline
                        terry.tzT Offline
                        terry.tz
                        wrote on last edited by
                        #36

                        @yegor said in Time to change wheels and ...:

                        http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php

                        I have read this and I would say read something else after reading it to put information in a better order for understanding

                        "Muddy water is best cleared by leaving it alone" Alan Watts

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                        0
                        • Y Offline
                          Y Offline
                          Yegor
                          wrote on last edited by Yegor
                          #37

                          @declan ok thanks, I think the same. But in PJME you can find the Genuine Yamaha base gasket and is the same that I have , made of metal ( I think steel )
                          http://www.pjme.co.uk/acatalog/4FU-11351-00.jpg

                          @Calum thx , I will pay attention to ring end gaps. And have bought the Athena head gasket and the original yamaha water pump radial shaft seal.

                          @terry-tz Thanks , will try read it in English ( I'm from Spain) , and find some literature in spanish.

                          Now I have disassembled the carburetor and I have understood much better how it works and how they connect the holes. this video helped me a lot:
                          Chicho Lorenzo ( Lorenzo's father MotoGP)
                          https://www.youtube.com/watch?v=niNn0LZESfg

                          My questions are. Our Mikuni carb ( TM 28 ) main original jet is 180 ?
                          in this webpage you can see specs and the main jet is 180 .
                          -> https://www.japanbaiku.com/mikuni/mikuni-tm/mikuni-tm28

                          . Now I have seen that I have 240 all this time , without problems. With the Romeu exhaust will try with 250/260. BUT this jet :
                          https://www.japanbaiku.com/image/cache/data/chicles_tornillos/kys-00b-500x500.jpg <--- ralenti/starter jet ? the original is 15 . will try 17.5

                          where do you buy jets kit ? www.japanbaiku.com is a little bit expensive.

                          Thanks in advance !

                          CalumC 1 Reply Last reply
                          0
                          • Y Yegor

                            @declan ok thanks, I think the same. But in PJME you can find the Genuine Yamaha base gasket and is the same that I have , made of metal ( I think steel )
                            http://www.pjme.co.uk/acatalog/4FU-11351-00.jpg

                            @Calum thx , I will pay attention to ring end gaps. And have bought the Athena head gasket and the original yamaha water pump radial shaft seal.

                            @terry-tz Thanks , will try read it in English ( I'm from Spain) , and find some literature in spanish.

                            Now I have disassembled the carburetor and I have understood much better how it works and how they connect the holes. this video helped me a lot:
                            Chicho Lorenzo ( Lorenzo's father MotoGP)
                            https://www.youtube.com/watch?v=niNn0LZESfg

                            My questions are. Our Mikuni carb ( TM 28 ) main original jet is 180 ?
                            in this webpage you can see specs and the main jet is 180 .
                            -> https://www.japanbaiku.com/mikuni/mikuni-tm/mikuni-tm28

                            . Now I have seen that I have 240 all this time , without problems. With the Romeu exhaust will try with 250/260. BUT this jet :
                            https://www.japanbaiku.com/image/cache/data/chicles_tornillos/kys-00b-500x500.jpg <--- ralenti/starter jet ? the original is 15 . will try 17.5

                            where do you buy jets kit ? www.japanbaiku.com is a little bit expensive.

                            Thanks in advance !

                            CalumC Online
                            CalumC Online
                            Calum
                            wrote on last edited by
                            #38

                            @yegor Hi bud,

                            240 main jet is fine, in your climate it probably about right. In colder climates then you would want to up jet slightly.

                            Jets are expensive, I cannot stress enough how important it is to buy genuine jets from reputable sellers.

                            Always Originate, Never Pirate!

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                            • terry.tzT Offline
                              terry.tzT Offline
                              terry.tz
                              wrote on last edited by
                              #39

                              @Yegor if your Spanish don't bother reading that old notebook crap it got everything you need to know but badly rote and explain get something in your native tongue

                              "Muddy water is best cleared by leaving it alone" Alan Watts

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                              • Y Offline
                                Y Offline
                                Yegor
                                wrote on last edited by
                                #40

                                @calum yes. those are original Mikuni jets. But what size is the ralenti jet ? 25 or 15 or what ?

                                ( https://www.japanbaiku.com/image/cache/data/chicles_tornillos/kys-00b-500x500.jpg ) thx!

                                CalumC 1 Reply Last reply
                                0
                                • Y Yegor

                                  @calum yes. those are original Mikuni jets. But what size is the ralenti jet ? 25 or 15 or what ?

                                  ( https://www.japanbaiku.com/image/cache/data/chicles_tornillos/kys-00b-500x500.jpg ) thx!

                                  CalumC Online
                                  CalumC Online
                                  Calum
                                  wrote on last edited by
                                  #41

                                  @yegor Pretty sure that's called the atomiser. No idea what a ralenti jet is, neither do I know what size it is. I don't run a mikuni carburetor so I cannot help you I am afraid.

                                  Always Originate, Never Pirate!

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                                  • Y Offline
                                    Y Offline
                                    Yegor
                                    wrote on last edited by
                                    #42

                                    @calum I was researching. I think in english is called " Pilot jet " and Mikuni TM28 pilot jet size is 15.

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                                    • Y Offline
                                      Y Offline
                                      Yegor
                                      wrote on last edited by
                                      #43

                                      sorry, the DT 125 "R" version is 17,5 pilot jet.

                                      1 Reply Last reply
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                                      • Y Offline
                                        Y Offline
                                        Yegor
                                        wrote on last edited by Yegor
                                        #44

                                        Hello, I don't know if is good idea to write in this thread . Today I was checking the oil pump and I realized that the color of the oil changed: it has a suspicious color )
                                        ( I have put a transparent tube to check the oil flow)
                                        0_1518129315115_27901538_10214764034192878_1048204166_o.jpg
                                        I think it's because of oil seal or o'ring
                                        0_1518129996122_27783450_10214764084834144_352994660_n.jpg
                                        11. O-RING
                                        -- 13. OIL SEAL

                                        WHat do you think ? Thanks in advance

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                                        0
                                        • CalumC Online
                                          CalumC Online
                                          Calum
                                          wrote on last edited by
                                          #45

                                          Is the pipe suitable for oil?

                                          Always Originate, Never Pirate!

                                          Y 1 Reply Last reply
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