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DT125R FORUM

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  4. Power valve o rings?

Power valve o rings?

Scheduled Pinned Locked Moved Engine
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  • S Offline
    S Offline
    SpookDog
    wrote on last edited by
    #1

    Where do the o rings fit, the orange ones? Also is there a gasket? Whoever built my engine last even had a black o ring sandwiched in. I really need a schematic or iTunes vid on how to reassemble the PV. I have the fixed PV with diamond end. It’s a 3bn engine with a 3mb barrel and head...
    Ta!

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    • S Offline
      S Offline
      SpookDog
      wrote on last edited by
      #2

      That’s utube not iTunes! Ducking spellcheck!

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      • CalumC Offline
        CalumC Offline
        Calum
        wrote on last edited by
        #3

        alt text

        You don't need a video to know how to disassemble it. It's like 5 pieces.

        Always Originate, Never Pirate!

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        • S Offline
          S Offline
          SpookDog
          wrote on last edited by
          #4

          I don’t know where the seal fit is all. Putting it together and in is no problem. I just don’t think it was correct when I took it out..

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

            Or are the orange seals for servo PVs only?...

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

              No 19 are the seals. They sit in the bushes.

              Always Originate, Never Pirate!

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

                The kickstart side is straightforward, simple groove that fits perfectly. It’s the gearchange side that has no groove or place for a seal. The previous owner had the orange one just flopping around and a black smaller o ring squashed flat between the bush and the cover. Neither of those two are affecting a seal. I’ll check and see if there’s a paper gasket for that side. That would be enough of a seal...
                It’s frustrating when the last owner didn’t know what they were doing, it makes reassembly a bear!...

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

                  The pictures are a give away.

                  The bush there has a groove cut out of it, the O-Ring sits inside the groove, the bush secures to powervalve in place.

                  Always Originate, Never Pirate!

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                  • S Offline
                    S Offline
                    SpookDog
                    wrote on last edited by
                    #9

                    Sorry bud? Pics? I get a link with ‘all text’ access denied.
                    Neither my bush or the cover have oring grooves on them, on that side. I wish I could post pics to show you what I mean but I just have a phone.

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                    • CalumC Offline
                      CalumC Offline
                      Calum
                      wrote on last edited by
                      #10

                      @SpookDog Oh Yeah 🤣 How annoying.

                      Sorry, it looks like they are blocking that resource.

                      It's a parts diagram showing you where the O-Rings go.

                      https://www.fowlersparts.co.uk/main/img/assemblies/large/e2bbdd33f448b949dadded717beb407f.png?6

                      I'll get it hosted elsewhere and link it in.

                      Always Originate, Never Pirate!

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                      • S Offline
                        S Offline
                        SpookDog
                        wrote on last edited by
                        #11

                        Fowler’s don’t like hotlinking apparently!😊
                        I found the diagram, unfortunately it is different from what I have fitted. I found I can affect a seal if I slip the oring over the end cap. Without it the whole cap/bush is very loose. It slops around loads! Whereas the other side is a good fit.
                        I wasn’t even sure if it was original to the barrel. Who knows what butchery was done before. The PV has 3bn on it I think, yet the barrel is 3mb. I don’t know if there’s a difference. I’m still fumbling around in the dark. The only other 2strokes I’ve worked on were air cooled, ts er’s, and more shedloads of Vespa & Lambretta’s than I can recall. I don’t recall them having an oring between them 🙂
                        Cheers bud!

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                        • CalumC Offline
                          CalumC Offline
                          Calum
                          wrote on last edited by
                          #12

                          The bushes wear out.

                          There were different types of powervalves, not sure how they differed on the bush side of things though.

                          Always Originate, Never Pirate!

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                          • S Offline
                            S Offline
                            SpookDog
                            wrote on last edited by
                            #13

                            One more question! Do you know what the black oring is for? I’ve got a full gasket set with black oring, but the only black oring I found was squashed into the PV and is obviously not right.
                            It’s about 3/4 inch.

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                            • S Offline
                              S Offline
                              SpookDog
                              wrote on last edited by
                              #14

                              Sorry, was busy thumb typing on a tiny screen!🤪
                              It’s not just the bush, the end cap it fits into also seems small. Plus it’s fixed, doesn’t move...
                              I’m guessing that the 3mb was a later servo operated valve? Totally different end cap on that side?...

                              CalumC 1 Reply Last reply
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                              • S SpookDog

                                Sorry, was busy thumb typing on a tiny screen!🤪
                                It’s not just the bush, the end cap it fits into also seems small. Plus it’s fixed, doesn’t move...
                                I’m guessing that the 3mb was a later servo operated valve? Totally different end cap on that side?...

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

                                @SpookDog the markings on the powervalve are misleading. I can't remember what is on the 3mb barrel. I do know that the two barrels take different valves, but I don't think the codes are representative.

                                Always Originate, Never Pirate!

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                                • NottsbikerN Offline
                                  NottsbikerN Offline
                                  Nottsbiker
                                  wrote on last edited by
                                  #16

                                  Dont do what I did when I was being stupid and try and fit the o-rings onto the power valve itself lol

                                  They go into the end caps and there is also an orange seal for the pulley end as well

                                  I also got a black o-ring in my Athena gasket kit from PJME and have no idea where it goes

                                  Wish it was the thermostat one as I need one but its the wrong size

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

                                    Thermostat is paper gasket IIRC. Kellogs Cereal will do.

                                    Always Originate, Never Pirate!

                                    NottsbikerN 1 Reply Last reply
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                                    • S Offline
                                      S Offline
                                      SpookDog
                                      wrote on last edited by
                                      #18

                                      Same as in my gasket set, it’s to small. You need a 33mm one for the thermostat. Get one from eBay. If you don’t have an account someone here will probably order it for you. It’ll be pennies ...

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                                      • S Offline
                                        S Offline
                                        SpookDog
                                        wrote on last edited by
                                        #19

                                        Sorry it’s 27mm Inner Diametre X 2.5 or 3mm Cross Section.

                                        Calum, cheers for the info bud, it puts my mind to rest. I always worry more when learning a new engine...

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                                        • CalumC Calum

                                          Thermostat is paper gasket IIRC. Kellogs Cereal will do.

                                          NottsbikerN Offline
                                          NottsbikerN Offline
                                          Nottsbiker
                                          wrote on last edited by
                                          #20

                                          @Calum there is an o-ring under the thermostat itself with the gasket above that

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