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DT125R FORUM

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  3. Derestricting
  4. Need to verify my bike year and model so i can look for restrictions

Need to verify my bike year and model so i can look for restrictions

Scheduled Pinned Locked Moved Derestricting
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  • OllieDTRO OllieDTR

    My French import (96) fitted with 3 pin power valve and full power cdi (3NC-00) happily do off the clocks and pulls better than my mates uk bikes, and that’s even with the 3BN restricted cylinder head. I’m in the process of rebuilding it and got the dome 3MB head off @HOTSHOT-III so I’m interested to see how that goes

    How many wires does your PV have?

    E Offline
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    erionmustafa
    wrote on last edited by
    #7

    @OllieDTR yes it 3cable 2with one plug and a black one with a different plug

    E 1 Reply Last reply
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    • E erionmustafa

      @OllieDTR yes it 3cable 2with one plug and a black one with a different plug

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      erionmustafa
      wrote on last edited by
      #8

      @erionmustafa im rebuilding it too rn my piston got fucked

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      • E erionmustafa

        @erionmustafa im rebuilding it too rn my piston got fucked

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        SpookDog
        wrote on last edited by
        #9

        @erionmustafa

        Well it happens to nearly everyone in time. At least you have the unrestricted version of the dtr125

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        • S SpookDog

          @erionmustafa

          Well it happens to nearly everyone in time. At least you have the unrestricted version of the dtr125

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          erionmustafa
          wrote on last edited by
          #10

          @SpookDog does it have exhaust restriction or can i do the speedo trick to get full speed or smth what can i do to it

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          • E erionmustafa

            @SpookDog does it have exhaust restriction or can i do the speedo trick to get full speed or smth what can i do to it

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            SpookDog
            wrote on last edited by
            #11

            @erionmustafa

            You have the 3 wire servo fitted to your power valve. Your bike is a full power model. There are no restrictions. Changing the exhaust may help unleash a few ponies, but your model was never intentionally restricted…

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            • S SpookDog

              @erionmustafa

              You have the 3 wire servo fitted to your power valve. Your bike is a full power model. There are no restrictions. Changing the exhaust may help unleash a few ponies, but your model was never intentionally restricted…

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              erionmustafa
              wrote on last edited by
              #12

              @SpookDog i want to cut the exhaust and remove the restrictor will i need to get a bigger carb jet or not

              S HOTSHOT IIIH 2 Replies Last reply
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              • E erionmustafa

                @SpookDog i want to cut the exhaust and remove the restrictor will i need to get a bigger carb jet or not

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                SpookDog
                wrote on last edited by SpookDog
                #13

                @erionmustafa

                You will never need to make the mixture richer with a bigger jet!…
                What makes you think that the exhaust is restricted? It’s a full power model, why would Yamaha go out of their way to restrict it? That said there are better ‘tuned’ exhausts out there…

                Someone else please chime in here?…

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                • E erionmustafa

                  @SpookDog i want to cut the exhaust and remove the restrictor will i need to get a bigger carb jet or not

                  HOTSHOT IIIH Offline
                  HOTSHOT IIIH Offline
                  HOTSHOT III
                  wrote on last edited by
                  #14

                  @erionmustafa Don't gut the stock exhaust, you'll probably lose power by doing that. When the DTR came out in 1988, they based the styling on the '88 YZ250 and the DTR front pipe is roughly the same size as the YZ, which is a single-skin racing exhaust system. On the DTR this allowed them to fit into this space an appropriately sized expansion chamber for a 125cc road bike and enough noise suppression material for the bike to be quiet enough for the roads/trails. So in most cases the front pipe isn't restricted on the DTR, I've heard stories of some of them having a washer in the header pipe but this would be pretty obvious and you wouldn't have to cut open the pipe to get to it.

                  You'd be better off getting an aftermarket pipe and trying that. On my 3NC the Tecno front pipe/DEP silencer combo worked well and the Tecno pipe costs around £100 even though it's identical to the Athena pipe. It gives a good spread of power from 5k to around 9k and I think the DEP front pipe would allow it to rev out a bit more, a bit faster but maybe not as good off road. I didn't need to re-jet for the Tecno and DEP advised me I wouldn't need to for their pipe either. @SpookDog runs the Romeu Henriques pipe and is happy with it. Any of these options will be good depending on what you want the bike to do, and if you ever want to sell it it will be worth more with a decent (i.e uncut) stock pipe fitted so paint this heatproof black and store it.

                  S 1 Reply Last reply
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                  • CalumC Offline
                    CalumC Offline
                    Calum
                    wrote on last edited by
                    #15

                    On my 2005 Yamaha DTRE, as well as the header restriction and a breather pipe back into the airbox, there was a huge honeycombe system inside the expansion chamber.

                    Regardless, the biggest resulting factor for me was the weight of the DEP compared to the stock pipe.

                    Always Originate, Never Pirate!

                    markus.wM 1 Reply Last reply
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                    • HOTSHOT IIIH HOTSHOT III

                      @erionmustafa Don't gut the stock exhaust, you'll probably lose power by doing that. When the DTR came out in 1988, they based the styling on the '88 YZ250 and the DTR front pipe is roughly the same size as the YZ, which is a single-skin racing exhaust system. On the DTR this allowed them to fit into this space an appropriately sized expansion chamber for a 125cc road bike and enough noise suppression material for the bike to be quiet enough for the roads/trails. So in most cases the front pipe isn't restricted on the DTR, I've heard stories of some of them having a washer in the header pipe but this would be pretty obvious and you wouldn't have to cut open the pipe to get to it.

                      You'd be better off getting an aftermarket pipe and trying that. On my 3NC the Tecno front pipe/DEP silencer combo worked well and the Tecno pipe costs around £100 even though it's identical to the Athena pipe. It gives a good spread of power from 5k to around 9k and I think the DEP front pipe would allow it to rev out a bit more, a bit faster but maybe not as good off road. I didn't need to re-jet for the Tecno and DEP advised me I wouldn't need to for their pipe either. @SpookDog runs the Romeu Henriques pipe and is happy with it. Any of these options will be good depending on what you want the bike to do, and if you ever want to sell it it will be worth more with a decent (i.e uncut) stock pipe fitted so paint this heatproof black and store it.

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                      SpookDog
                      wrote on last edited by
                      #16

                      @HOTSHOT-III

                      Is the Tecno the “unrestricted pipe” that appears on eBay, for about £100? Doesn’t look too shabbily made (though not well finished/painted) It was going to be my first choice until I got put into touch with HR. I wasn’t willing to throw down the money for a DEP. I think that they’re overpriced, but that’s just my gut feeling. Not that they’re bad. Just flimsy with no longevity. I’d rather pay £350 once, not once every couple years 😛 …

                      Dtre’s seem to be one of the most horribly restricted iterations of the bike from what I’ve read!…

                      PS I think that Hotshot has a really sweet 3MB front pipe for sale. I would of bought it if I had enough disposable income 🙂 …

                      HOTSHOT IIIH E CalumC 3 Replies Last reply
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                      • S SpookDog

                        @HOTSHOT-III

                        Is the Tecno the “unrestricted pipe” that appears on eBay, for about £100? Doesn’t look too shabbily made (though not well finished/painted) It was going to be my first choice until I got put into touch with HR. I wasn’t willing to throw down the money for a DEP. I think that they’re overpriced, but that’s just my gut feeling. Not that they’re bad. Just flimsy with no longevity. I’d rather pay £350 once, not once every couple years 😛 …

                        Dtre’s seem to be one of the most horribly restricted iterations of the bike from what I’ve read!…

                        PS I think that Hotshot has a really sweet 3MB front pipe for sale. I would of bought it if I had enough disposable income 🙂 …

                        HOTSHOT IIIH Offline
                        HOTSHOT IIIH Offline
                        HOTSHOT III
                        wrote on last edited by
                        #17

                        @SpookDog The Tecno is the unrestricted pipe on ebay yes. It's well made, fits well and is pretty solid, only bad point is the clearcoat that bubbles off the header and is too tough to remove for painting everywhere else. If I bought another brand new one now I'd probably try paintstripper before fitting it, then just paint it heatproof black

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                        • S SpookDog

                          @HOTSHOT-III

                          Is the Tecno the “unrestricted pipe” that appears on eBay, for about £100? Doesn’t look too shabbily made (though not well finished/painted) It was going to be my first choice until I got put into touch with HR. I wasn’t willing to throw down the money for a DEP. I think that they’re overpriced, but that’s just my gut feeling. Not that they’re bad. Just flimsy with no longevity. I’d rather pay £350 once, not once every couple years 😛 …

                          Dtre’s seem to be one of the most horribly restricted iterations of the bike from what I’ve read!…

                          PS I think that Hotshot has a really sweet 3MB front pipe for sale. I would of bought it if I had enough disposable income 🙂 …

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                          erionmustafa
                          wrote on last edited by
                          #18

                          @SpookDog i tried my best to understand the derestricting guides but as you guys are saying it seems for me to be blessed with a unrestricted one
                          PS i didn't notice that the power valve was stuck half open and wasn't getting enough power so i reduced front sprocket to 14 and seemed to catch 80kmh i can't wait till i fix the cylinder and get a piston to test it i was surprised when i found out that i wasn't getting full power and with a 14tooth sprocket doing 80kmh its crazy

                          1 Reply Last reply
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                          • S SpookDog

                            @HOTSHOT-III

                            Is the Tecno the “unrestricted pipe” that appears on eBay, for about £100? Doesn’t look too shabbily made (though not well finished/painted) It was going to be my first choice until I got put into touch with HR. I wasn’t willing to throw down the money for a DEP. I think that they’re overpriced, but that’s just my gut feeling. Not that they’re bad. Just flimsy with no longevity. I’d rather pay £350 once, not once every couple years 😛 …

                            Dtre’s seem to be one of the most horribly restricted iterations of the bike from what I’ve read!…

                            PS I think that Hotshot has a really sweet 3MB front pipe for sale. I would of bought it if I had enough disposable income 🙂 …

                            CalumC Offline
                            CalumC Offline
                            Calum
                            wrote on last edited by
                            #19

                            @SpookDog The RE's/X's are the easiest to derestrict. Green/Black wire on the CDI needs to be earthed to the frame and the CDI is fully derestricted. Then it's just an aftermarket pipe.

                            Always Originate, Never Pirate!

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                            • CalumC Calum

                              On my 2005 Yamaha DTRE, as well as the header restriction and a breather pipe back into the airbox, there was a huge honeycombe system inside the expansion chamber.

                              Regardless, the biggest resulting factor for me was the weight of the DEP compared to the stock pipe.

                              markus.wM Offline
                              markus.wM Offline
                              markus.w
                              wrote on last edited by
                              #20

                              @Calum the RE/X models have catalytic converters inside the expansion chambers. Unlike the the Japanese built 125R models, they had to conform to European emmisions regulations. This rule came out in 2003.

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                              • CalumC Calum

                                @SpookDog The RE's/X's are the easiest to derestrict. Green/Black wire on the CDI needs to be earthed to the frame and the CDI is fully derestricted. Then it's just an aftermarket pipe.

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                                erionmustafa
                                wrote on last edited by
                                #21

                                @Calum previous owner put a fake akrapovic slip on that is for 4strokes can it make lose power or anything ??

                                CalumC S 2 Replies Last reply
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                                • E erionmustafa

                                  @Calum previous owner put a fake akrapovic slip on that is for 4strokes can it make lose power or anything ??

                                  CalumC Offline
                                  CalumC Offline
                                  Calum
                                  wrote on last edited by Calum
                                  #22

                                  @erionmustafa Uhhmm absolutely. You want a proper two stroke exhaust to go with the expansion chamber.

                                  https://www.motorcycle.com/how-to/how-twostroke-expansion-chambers-work-and-why-you-should-care-3423.html

                                  In addition to head pipe length, divergent and convergent cone lengths, an expansion chamber has three more crucial dimensions. 
                                  The length of the straight 'belly' between the divergent and the convergent cones, the length of the tailpiece 'stinger', or muffler, and the diameter of the belly section.
                                  The stinger acts as a pressure bleed, allowing pressure to escape from the pipe. Back pressure in the pipe, caused by a smaller-diameter or longer stinger section, helps the wave action of the pipe, and can increase the engine's performance. 
                                  

                                  Always Originate, Never Pirate!

                                  1 Reply Last reply
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                                  • E erionmustafa

                                    @Calum previous owner put a fake akrapovic slip on that is for 4strokes can it make lose power or anything ??

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                                    SpookDog
                                    wrote on last edited by
                                    #23

                                    @erionmustafa

                                    My bike would barely do 55mph when I tried a 14 tooth front sprocket, I use a 17 tooth front sprocket now and it’s absolutely perfect gearing for me…

                                    E 1 Reply Last reply
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                                    • S SpookDog

                                      @erionmustafa

                                      My bike would barely do 55mph when I tried a 14 tooth front sprocket, I use a 17 tooth front sprocket now and it’s absolutely perfect gearing for me…

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                                      erionmustafa
                                      wrote on last edited by
                                      #24

                                      @SpookDog 17is too bog for offroad as i use the bike for enduro to its limits so i need smaller front to climb better maybe i'll upgrade to 15 or 16 but 17 is a little to much

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                                      • E erionmustafa

                                        @SpookDog 17is too bog for offroad as i use the bike for enduro to its limits so i need smaller front to climb better maybe i'll upgrade to 15 or 16 but 17 is a little to much

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                                        SpookDog
                                        wrote on last edited by SpookDog
                                        #25

                                        @erionmustafa

                                        Oh hell yeah, 17 is road cruise stuff, but it really suits the 22 horses I think are going on with my bike…

                                        It’s whatever suits you. If you need some 15 or 16 front sprockets let me know, you can have them (unused) I might even have a 13 kicking around somewhere, unless my memory has finally failed me! Just pay the postage 🙂 …

                                        I’ve got a ‘hardly used’ 55 rear as well, just to confuse the mix 😛. …

                                        Regarding the tailpipe/silencer, as long as the inner diameter of the baffle isn’t smaller than the ‘stinger’ end of the expansion chamber-front end, I wouldn’t of thought it would make any difference to performance. But! I am no expert by any means. Also I don’t mind being proven wrong ☠️ …

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                                        • S SpookDog

                                          @erionmustafa

                                          Oh hell yeah, 17 is road cruise stuff, but it really suits the 22 horses I think are going on with my bike…

                                          It’s whatever suits you. If you need some 15 or 16 front sprockets let me know, you can have them (unused) I might even have a 13 kicking around somewhere, unless my memory has finally failed me! Just pay the postage 🙂 …

                                          I’ve got a ‘hardly used’ 55 rear as well, just to confuse the mix 😛. …

                                          Regarding the tailpipe/silencer, as long as the inner diameter of the baffle isn’t smaller than the ‘stinger’ end of the expansion chamber-front end, I wouldn’t of thought it would make any difference to performance. But! I am no expert by any means. Also I don’t mind being proven wrong ☠️ …

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                                          erionmustafa
                                          wrote on last edited by
                                          #26

                                          @SpookDog its for 4strokes or road bikes im not sure my cousin welded it somehow but the silencer itself is wider where it connects and wider on the inside to it has the db killer removed and all the packing burnt on pourpuse it makes hella noise you can hear it from far away like if its a 250 or smth

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