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DT125R FORUM

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Piston movement

Scheduled Pinned Locked Moved Engine
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  • OllieDTRO Offline
    OllieDTRO Offline
    OllieDTR
    wrote on last edited by
    #1

    Hi guys
    With my bike before I got it, it had a rebore and new piston 1.00 oversize, I’ve done the run in and I’m only getting 105psi so I thought I’d take the head off to look at the inside, cross hatching is lovely but piston has knock when you have it at TDC and rub it with your fingers you can feel it has play and see it also, what would cause that? The barrel is in perfect condition aswell as the piston, do you think I need another rebore or get some new rings for the piston and should sort it?

    S 1 Reply Last reply
    0
    • CalumC Offline
      CalumC Offline
      Calum
      wrote on last edited by
      #2

      105 PSI is way too low. Something doesn't sound right. The piston should be snug in the bore.

      Time to get out the bore indicator gauge and measure it and the piston.

      Always Originate, Never Pirate!

      1 Reply Last reply
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      • OllieDTRO OllieDTR

        Hi guys
        With my bike before I got it, it had a rebore and new piston 1.00 oversize, I’ve done the run in and I’m only getting 105psi so I thought I’d take the head off to look at the inside, cross hatching is lovely but piston has knock when you have it at TDC and rub it with your fingers you can feel it has play and see it also, what would cause that? The barrel is in perfect condition aswell as the piston, do you think I need another rebore or get some new rings for the piston and should sort it?

        S Offline
        S Offline
        SpookDog
        wrote on last edited by SpookDog
        #3

        @OllieDTR

        I’ve had same issues when I bought a barrel with an amateur rebore. It was noisy and horrible. I get my rebores done by PJME, they are always snug as a bug in the barrel…
        I’d be inclined to send your barrel & piston off to a reputable company to get it checked out properly by someone with the proper tools who knows what they’re doing…

        OllieDTRO 1 Reply Last reply
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        • S SpookDog

          @OllieDTR

          I’ve had same issues when I bought a barrel with an amateur rebore. It was noisy and horrible. I get my rebores done by PJME, they are always snug as a bug in the barrel…
          I’d be inclined to send your barrel & piston off to a reputable company to get it checked out properly by someone with the proper tools who knows what they’re doing…

          OllieDTRO Offline
          OllieDTRO Offline
          OllieDTR
          wrote on last edited by
          #4

          @SpookDog

          PJME looks spot on mate what’s the turn around time do you know?
          do you know if they do porting aswell?
          I’ll get in contact with them

          S 1 Reply Last reply
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          • OllieDTRO OllieDTR

            @SpookDog

            PJME looks spot on mate what’s the turn around time do you know?
            do you know if they do porting aswell?
            I’ll get in contact with them

            S Offline
            S Offline
            SpookDog
            wrote on last edited by
            #5

            @OllieDTR

            I don’t know about porting, I’ve never had any interest, so I never looked into it. If I was going to do anything it’d be an abused 2nd hand Athena 170 that I’d get sleeved with a cast liner…

            Turn around depends on how busy they are. Sorry, not what you want to hear! 🙂 I’ve waited 3 weeks at the height of covid, then well under 2 recently…

            Callum would be the person for advice about porting. Mike Abbot, or Mike someone 🙂 As long as they’re reputable then you only have to pay once…

            OllieDTRO 1 Reply Last reply
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            • S SpookDog

              @OllieDTR

              I don’t know about porting, I’ve never had any interest, so I never looked into it. If I was going to do anything it’d be an abused 2nd hand Athena 170 that I’d get sleeved with a cast liner…

              Turn around depends on how busy they are. Sorry, not what you want to hear! 🙂 I’ve waited 3 weeks at the height of covid, then well under 2 recently…

              Callum would be the person for advice about porting. Mike Abbot, or Mike someone 🙂 As long as they’re reputable then you only have to pay once…

              OllieDTRO Offline
              OllieDTRO Offline
              OllieDTR
              wrote on last edited by
              #6

              @SpookDog

              I’ve messaged Mickey abbey tuning and see what price he gives me! I did remember speaking to him on the phone awhile ago as he was going to machine my 3bn head so it’s like the 3mb head so will get it all done at once, I’ve heard proper porting on a 125 is the nuts

              S 1 Reply Last reply
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              • OllieDTRO OllieDTR

                @SpookDog

                I’ve messaged Mickey abbey tuning and see what price he gives me! I did remember speaking to him on the phone awhile ago as he was going to machine my 3bn head so it’s like the 3mb head so will get it all done at once, I’ve heard proper porting on a 125 is the nuts

                S Offline
                S Offline
                SpookDog
                wrote on last edited by
                #7

                @OllieDTR

                Bud! You’re talking to the wrong person! I think you’re wasting your money…
                I’ll shut up now 😛 …

                OllieDTRO 1 Reply Last reply
                0
                • S SpookDog

                  @OllieDTR

                  Bud! You’re talking to the wrong person! I think you’re wasting your money…
                  I’ll shut up now 😛 …

                  OllieDTRO Offline
                  OllieDTRO Offline
                  OllieDTR
                  wrote on last edited by
                  #8

                  @SpookDog

                  Rang Mickey abbey, he said porting is pretty good on the dts anyways so probably won’t do to much that is crazy noticeable, did ring PJME, same turn around time 2 to 3 weeks I’ve seen and read good things about Mickey abbey tuning and been going years so will be sending to him and he’s only £35 for rebore! Win win

                  1 Reply Last reply
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                  • CalumC Offline
                    CalumC Offline
                    Calum
                    wrote on last edited by
                    #9

                    I've had a few barrels done my Mick on my bikes. Both the 3MB000P and a 170 barrel and the difference in porting has always been night and day. The difference in performance is something else. I have never been great at actually "feeling" the difference.

                    Bikes with the dyno at the moment so I can post up how it gets on.

                    The base performance of the DTR is weak IMO. Compared to Aprilia/Cagiva barrels it is a very slow/detuned motor. Porting it may help, but you're very limited in what you can achieve with the standard setup.

                    In my experience, the DTR never favoured aggressive porting as it's best ridden in the mid range, due to its setup of being a trail bike. My fondest memories of the bike was probably when it was mildly tuned before I had it ported.

                    I was, at the time, 70kgs wet and that obviously accounted for most of the performance.

                    Now, coming in at more around the 90kgs, having the 170 kit makes the world of difference, but the bike has lost a lot of overrev. Now I pootle around at 4k and probably maxes it out at 10k.

                    It's setup lovely how it is at the moment and I cannot wait to get it back from the dyno.

                    Always Originate, Never Pirate!

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