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DT125R FORUM

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Bike running fast revs

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  • declanD declan

    @calum lol got it in pretty easy but it’s still revving to the moon no air leaks cable is 100% free safe to say I’m pretty clue less and pissed off

    CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #15

    @declan If it was working fine before hand, then it's going to be something properly simple. Rushing isn't going to fix the problem.

    My guess is that it's an air leak, because this is the most common type of problem.

    The inlet manifold gasket should be renewed. As said previously, these are prone to failure upon renewal.

    You said your inlet had a split in it, have you replaced the inlet? Sounds like it's past its best and I would renew it with a new one whilsy Yamaha still make them...

    Always Originate, Never Pirate!

    declanD 1 Reply Last reply
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    • CalumC Calum

      @declan If it was working fine before hand, then it's going to be something properly simple. Rushing isn't going to fix the problem.

      My guess is that it's an air leak, because this is the most common type of problem.

      The inlet manifold gasket should be renewed. As said previously, these are prone to failure upon renewal.

      You said your inlet had a split in it, have you replaced the inlet? Sounds like it's past its best and I would renew it with a new one whilsy Yamaha still make them...

      declanD Offline
      declanD Offline
      declan
      wrote on last edited by
      #16

      @calum your right it just has to be an air leak there’s no other explanation so if I use wd40 should I be looking for bubbles as rpm change will not be reliable

      CalumC 1 Reply Last reply
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      • declanD declan

        @calum your right it just has to be an air leak there’s no other explanation so if I use wd40 should I be looking for bubbles as rpm change will not be reliable

        CalumC Offline
        CalumC Offline
        Calum
        wrote on last edited by
        #17

        @declan The added WD-40 should be combustable, bringing the mixture down so the idle should drop.

        It'll be something simple. It might be that the reeds are installed incorrectly. Too Much overlap at the end etc...

        Always Originate, Never Pirate!

        declanD 1 Reply Last reply
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        • CalumC Calum

          @declan The added WD-40 should be combustable, bringing the mixture down so the idle should drop.

          It'll be something simple. It might be that the reeds are installed incorrectly. Too Much overlap at the end etc...

          declanD Offline
          declanD Offline
          declan
          wrote on last edited by
          #18

          @calum checked before install they were a perfect fit and actuall were the same ones that were already in there

          declanD 1 Reply Last reply
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          • declanD declan

            @calum checked before install they were a perfect fit and actuall were the same ones that were already in there

            declanD Offline
            declanD Offline
            declan
            wrote on last edited by
            #19

            @declan should there be a gasket between the engine and the reed block spacer

            CalumC 1 Reply Last reply
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            • O Offline
              O Offline
              oldman
              wrote on last edited by
              #20

              Yes 0_1507742590451_20171011_182026-979x1305.jpg

              1 Reply Last reply
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              • declanD declan

                @declan should there be a gasket between the engine and the reed block spacer

                CalumC Offline
                CalumC Offline
                Calum
                wrote on last edited by
                #21

                @declan That was literally one of the things I rattled off before hand...

                Always Originate, Never Pirate!

                declanD 1 Reply Last reply
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                • CalumC Calum

                  @declan That was literally one of the things I rattled off before hand...

                  declanD Offline
                  declanD Offline
                  declan
                  wrote on last edited by
                  #22

                  @calum yes but my bike doesent have one @oldman is there two of those gaskets?

                  CalumC 1 Reply Last reply
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                  • declanD declan

                    @calum yes but my bike doesent have one @oldman is there two of those gaskets?

                    CalumC Offline
                    CalumC Offline
                    Calum
                    wrote on last edited by Calum
                    #23

                    @declan No

                    alt text

                    Item 8 and be sure to buy either genuine or Athena.

                    As said, it's common for them to go there on these bikes because people either do naff copies, use inferior parts or reuse gaskets.

                    Always Originate, Never Pirate!

                    declanD 1 Reply Last reply
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                    • CalumC Calum

                      @declan No

                      alt text

                      Item 8 and be sure to buy either genuine or Athena.

                      As said, it's common for them to go there on these bikes because people either do naff copies, use inferior parts or reuse gaskets.

                      declanD Offline
                      declanD Offline
                      declan
                      wrote on last edited by
                      #24

                      @calum see I have a gasket underneath the inlet manifold is this in the wrong place then Bud?

                      CalumC 1 Reply Last reply
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                      • declanD declan

                        @calum see I have a gasket underneath the inlet manifold is this in the wrong place then Bud?

                        CalumC Offline
                        CalumC Offline
                        Calum
                        wrote on last edited by
                        #25

                        @declan The inlet is "Rubber" therefore doesn't need a gasket.

                        The Engine is metal and therefore needs a gasket.

                        So yes. As I said at the start, it's an airleak. It's where I suspected it to be.

                        Always Originate, Never Pirate!

                        declanD 1 Reply Last reply
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                        • CalumC Calum

                          @declan The inlet is "Rubber" therefore doesn't need a gasket.

                          The Engine is metal and therefore needs a gasket.

                          So yes. As I said at the start, it's an airleak. It's where I suspected it to be.

                          declanD Offline
                          declanD Offline
                          declan
                          wrote on last edited by
                          #26

                          @calum I’ll get the gasket switched round tomorrow and we will see how it goes thanks for you time mate

                          CalumC 1 Reply Last reply
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                          • declanD declan

                            @calum I’ll get the gasket switched round tomorrow and we will see how it goes thanks for you time mate

                            CalumC Offline
                            CalumC Offline
                            Calum
                            wrote on last edited by
                            #27

                            @declan As said, really that gasket should be renewed!

                            It's your bike do as you please, If you were a more experienced engine builder, I would defer to your judgement on whether or not that gasket could be reused.

                            But as you got it the wrong way around, I would say you're not too experienced.

                            It may work and cause no problems, it may fail on you when you're out and miles from home.

                            I would renew the gasket personally, saves yourself from headache down the line.

                            Always Originate, Never Pirate!

                            declanD 1 Reply Last reply
                            1
                            • CalumC Calum

                              @declan As said, really that gasket should be renewed!

                              It's your bike do as you please, If you were a more experienced engine builder, I would defer to your judgement on whether or not that gasket could be reused.

                              But as you got it the wrong way around, I would say you're not too experienced.

                              It may work and cause no problems, it may fail on you when you're out and miles from home.

                              I would renew the gasket personally, saves yourself from headache down the line.

                              declanD Offline
                              declanD Offline
                              declan
                              wrote on last edited by declan
                              #28

                              @calum I didn’t put it on the wrong way it was already like that and I’ve worked on bikes all my life and did 2 years mechanics course at college but no I couldn’t say I’m an experienced engine builder but I wouldn’t re use a gasket if I thought it was bad

                              CalumC 1 Reply Last reply
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                              • declanD declan

                                @calum I didn’t put it on the wrong way it was already like that and I’ve worked on bikes all my life and did 2 years mechanics course at college but no I couldn’t say I’m an experienced engine builder but I wouldn’t re use a gasket if I thought it was bad

                                CalumC Offline
                                CalumC Offline
                                Calum
                                wrote on last edited by
                                #29

                                @declan Okay sorry bud. Was jut the vibe I was getting.

                                Put it this way, on engines, if you have two meeting surfaces, they should be surpressed with a gasket.

                                The reason why the inlet manifold doesn't need a gasket between the reed cage is because the inlet manifold is rubber,

                                But metal on metal definitely needs a gasket.

                                Always Originate, Never Pirate!

                                1 Reply Last reply
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                                • O Offline
                                  O Offline
                                  oldman
                                  wrote on last edited by
                                  #30

                                  Experience has kicked me up the butt more than once (I am, after all, an old man!) and personally always use new seals,gaskets etc when refitting something, mainly because when problems arise like you are experiencing I know I can rule out a duff seal (you do get duff new ones occasionally, quality counts) and have been using Athena kits that have proved to be reliable.There is nothing worse than stripping something down you have just meticulously rebuilt because of a "minor" hiccup. By the way, I hate fitting that rubber boot as well, my fingers are a bit to pudgy to fit comfortably in the airbox

                                  declanD 1 Reply Last reply
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                                  • O oldman

                                    Experience has kicked me up the butt more than once (I am, after all, an old man!) and personally always use new seals,gaskets etc when refitting something, mainly because when problems arise like you are experiencing I know I can rule out a duff seal (you do get duff new ones occasionally, quality counts) and have been using Athena kits that have proved to be reliable.There is nothing worse than stripping something down you have just meticulously rebuilt because of a "minor" hiccup. By the way, I hate fitting that rubber boot as well, my fingers are a bit to pudgy to fit comfortably in the airbox

                                    declanD Offline
                                    declanD Offline
                                    declan
                                    wrote on last edited by
                                    #31

                                    @oldman thanks guys just pretty discouraged right now just feel like I can’t catch a break hopefully if I keep going it will work as it should

                                    1 Reply Last reply
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                                    • O Offline
                                      O Offline
                                      oldman
                                      wrote on last edited by
                                      #32

                                      Know how you feel, felt the same when my inlet rubber split, take a break and get back to it with a clear head.

                                      declanD 1 Reply Last reply
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                                      • O oldman

                                        Know how you feel, felt the same when my inlet rubber split, take a break and get back to it with a clear head.

                                        declanD Offline
                                        declanD Offline
                                        declan
                                        wrote on last edited by
                                        #33

                                        @oldman thank you hopefully it will start and idle tomorrow

                                        1 Reply Last reply
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                                        • S Offline
                                          S Offline
                                          scrimsmustang
                                          wrote on last edited by
                                          #34

                                          Is this reving high as soon as you start it ? Common things that will cause it also are a blown or incorrectly sealed cylinder base gasket or a leaking left crank seal, its usually the left side that goes they dry out and perish over time. Only a couple of quid and easy to fit, same with the base gasket.

                                          declanD 1 Reply Last reply
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