Skip to content
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
Skins
  • Light
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (Slate)
  • No Skin
Collapse
Brand Logo

DT125R FORUM

  1. Home
  2. Tuning
  3. Top End
  4. Lapping

Lapping

Scheduled Pinned Locked Moved Top End
19 Posts 5 Posters 1.6k Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • CalumC Offline
    CalumC Offline
    Calum
    wrote on last edited by
    #2

    I doubt you'll get it to seal.

    Back in the Air Cooled days, the engines were cast iron. As such they were less prone to warping. Aluminium will literally just warp.

    The best you can get is a machine O-Ring into the head to eliminate the head gasket. The Rotax engines use these.

    You have to be careful with how much compression you run, pre-ignition and detonation is going to creep in at these sorts of levels and kill your engine.

    Always Originate, Never Pirate!

    1 Reply Last reply
    0
    • BluestoesonnoseB Offline
      BluestoesonnoseB Offline
      Bluestoesonnose
      wrote on last edited by
      #3

      LC motors are alloy and it seems to be a wide spread practice with the aircooled and watercool boys back in the heydays.

      2002 DT125R

      CalumC 1 Reply Last reply
      0
      • BluestoesonnoseB Bluestoesonnose

        LC motors are alloy and it seems to be a wide spread practice with the aircooled and watercool boys back in the heydays.

        CalumC Offline
        CalumC Offline
        Calum
        wrote on last edited by
        #4

        @Bluestoesonnose I know LC motors are alloy, I was specifically referring to the AC motors since I'd expect this to be where it would work reliably.

        But I've not heard anyone do it to DT's. I guess there must be a reason why it's not so common these days.

        Always Originate, Never Pirate!

        1 Reply Last reply
        0
        • BluestoesonnoseB Offline
          BluestoesonnoseB Offline
          Bluestoesonnose
          wrote on last edited by
          #5

          Not totally clear in your reply

          2002 DT125R

          CalumC 1 Reply Last reply
          0
          • BluestoesonnoseB Bluestoesonnose

            Not totally clear in your reply

            CalumC Offline
            CalumC Offline
            Calum
            wrote on last edited by
            #6

            @Bluestoesonnose I'm not saying it's not possible, I do question it's reliability. O-Ring modification would probably be your best bet. But the discussed factors should be considered.

            Always Originate, Never Pirate!

            1 Reply Last reply
            0
            • 2 Offline
              2 Offline
              2stroketerry
              wrote on last edited by
              #7

              The O-ring conversion on a DT 125 using a 90,s YZ 125 O-ring , the tighter squish and less combustion volume really helped. On average I would say this mod gives around 1,0 a 1,5 HP. This will lower the squish from +/-1.35 to a +/-0.95mm
              0_1541544295916_DT.jpg

              CalumC 1 Reply Last reply
              1
              • 2 2stroketerry

                The O-ring conversion on a DT 125 using a 90,s YZ 125 O-ring , the tighter squish and less combustion volume really helped. On average I would say this mod gives around 1,0 a 1,5 HP. This will lower the squish from +/-1.35 to a +/-0.95mm
                0_1541544295916_DT.jpg

                CalumC Offline
                CalumC Offline
                Calum
                wrote on last edited by
                #8

                @2stroketerry That looks the tits. Who did that for you?

                Always Originate, Never Pirate!

                1 Reply Last reply
                0
                • 2 Offline
                  2 Offline
                  2stroketerry
                  wrote on last edited by
                  #9

                  Cost £30 to cut the groove from a machine shop in Southbank
                  0_1541546069494_DT2.jpg

                  declanD 1 Reply Last reply
                  0
                  • 2 2stroketerry

                    Cost £30 to cut the groove from a machine shop in Southbank
                    0_1541546069494_DT2.jpg

                    declanD Offline
                    declanD Offline
                    declan
                    wrote on last edited by
                    #10

                    @2stroketerry I’m surprised you lot like the o rings I hate them with a passion I love the simple metal one like dt has I’m always having leaks and such from poorly fitted o rings even though I try my best to fit them perfectly

                    CalumC 1 Reply Last reply
                    0
                    • declanD declan

                      @2stroketerry I’m surprised you lot like the o rings I hate them with a passion I love the simple metal one like dt has I’m always having leaks and such from poorly fitted o rings even though I try my best to fit them perfectly

                      CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #11

                      @declan That's your problem then isn't it. Poorly fitted.

                      I've not had issues with O-Ring gaskets. Usually a dab of grease to hold it in situ is enough to sort any problems out if you're having them.

                      Always Originate, Never Pirate!

                      declanD 1 Reply Last reply
                      0
                      • CalumC Calum

                        @declan That's your problem then isn't it. Poorly fitted.

                        I've not had issues with O-Ring gaskets. Usually a dab of grease to hold it in situ is enough to sort any problems out if you're having them.

                        declanD Offline
                        declanD Offline
                        declan
                        wrote on last edited by
                        #12

                        @Calum none of that worked for me they wouldn’t sit still the last one I did I used the lightest amount of super glue just enough to keep it in the groove and that worked any other time and it would always slip out an pinch the ring I should add this is on the cheap replica rs cylinders so the machining wasn’t exactly flawless

                        1 Reply Last reply
                        0
                        • 2 Offline
                          2 Offline
                          2stroketerry
                          wrote on last edited by
                          #13

                          @declan using glue is the last thing you want on an O-ring just a bit of silicone grease, but having a poorly machined groove the O-ring sits in probably doesn't help.
                          Yamaha use an O-ring on there best 125 cylinders the SP although don't actualy make that cylinder themselves.

                          declanD 1 Reply Last reply
                          0
                          • NINJAN Offline
                            NINJAN Offline
                            NINJA
                            wrote on last edited by NINJA
                            #14

                            I seem to remember someone once said that applying a bit of petroleum jelly, aka the good ole Vaseline works wonders for keeping your 'O' ring in good order.

                            :grinning_face_with_smiling_eyes: :winking_face: :grinning_face_with_smiling_eyes::winking_face: :grinning_face_with_smiling_eyes:

                            SEDUCED BY THE DARK SIDE!!!

                            declanD 1 Reply Last reply
                            1
                            • 2 2stroketerry

                              @declan using glue is the last thing you want on an O-ring just a bit of silicone grease, but having a poorly machined groove the O-ring sits in probably doesn't help.
                              Yamaha use an O-ring on there best 125 cylinders the SP although don't actualy make that cylinder themselves.

                              declanD Offline
                              declanD Offline
                              declan
                              wrote on last edited by
                              #15

                              @2stroketerry the only bike I didn’t have a problem with was a yz 125 that was no issues what so ever

                              1 Reply Last reply
                              0
                              • NINJAN NINJA

                                I seem to remember someone once said that applying a bit of petroleum jelly, aka the good ole Vaseline works wonders for keeping your 'O' ring in good order.

                                :grinning_face_with_smiling_eyes: :winking_face: :grinning_face_with_smiling_eyes::winking_face: :grinning_face_with_smiling_eyes:

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

                                @NINJA you’d know

                                NINJAN 1 Reply Last reply
                                0
                                • declanD declan

                                  @NINJA you’d know

                                  NINJAN Offline
                                  NINJAN Offline
                                  NINJA
                                  wrote on last edited by
                                  #17

                                  @declan Do not tell me that you did not laugh at that one???

                                  SEDUCED BY THE DARK SIDE!!!

                                  declanD 1 Reply Last reply
                                  0
                                  • NINJAN NINJA

                                    @declan Do not tell me that you did not laugh at that one???

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

                                    @NINJA sorry to say I didn’t i take my o rings very seriously I’m quite anal about o rings

                                    1 Reply Last reply
                                    1
                                    • CalumC Offline
                                      CalumC Offline
                                      Calum
                                      wrote on last edited by
                                      #19

                                      Like with most things, the work is in the preparation.

                                      Always Originate, Never Pirate!

                                      1 Reply Last reply
                                      0
                                      Reply
                                      • Reply as topic
                                      Log in to reply
                                      • Oldest to Newest
                                      • Newest to Oldest
                                      • Most Votes


                                      • Login

                                      • Don't have an account? Register

                                      • Login or register to search.
                                      • First post
                                        Last post
                                      0
                                      • Recent
                                      • Tags
                                      • Popular
                                      • Users
                                      • Groups