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DT125R FORUM

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1988 bike

Scheduled Pinned Locked Moved DTR
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  • O Offline
    O Offline
    oldman
    wrote on last edited by
    #21

    Will not need to though if it's an 88 engine? Just need to make sure crank is correct for stroke, will check part nos to be sure.

    CalumC 1 Reply Last reply
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    • O oldman

      Will not need to though if it's an 88 engine? Just need to make sure crank is correct for stroke, will check part nos to be sure.

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

      @oldman If it was running a 3MB and you put a 3BN barrel on it, the stroke will be too long. Is it the crank, is it the rod? I don't know. But the stroke is definitely different. So you will want to make sure you have clearance.

      Always Originate, Never Pirate!

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      • O Offline
        O Offline
        oldman
        wrote on last edited by
        #23

        Checked fowlers for part no, con rod for 88 listed as separate item, later years checked a(89 and 1990) and shows discontinued with no part nos? Have ordered a genuine 88 one to be sure but any info you have useful? Original barrel was already 1.75 over hence the replacement

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        • O Offline
          O Offline
          oldman
          wrote on last edited by
          #24

          It's definitely an 88 bike and engine, the barrel was consistent with engine and I did have a spare 3mb barrel but sourced like for like. Cant be sure con rod in engine is correct hence ordering correct one from fowlers. Could be whole crank differs from later bikes but don't know (yet) will check clearances as built, lucky to find a matching barrel to be honest

          CalumC 1 Reply Last reply
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          • O oldman

            It's definitely an 88 bike and engine, the barrel was consistent with engine and I did have a spare 3mb barrel but sourced like for like. Cant be sure con rod in engine is correct hence ordering correct one from fowlers. Could be whole crank differs from later bikes but don't know (yet) will check clearances as built, lucky to find a matching barrel to be honest

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

            @oldman Yeah this.

            The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.

            It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.

            As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!

            Always Originate, Never Pirate!

            O 1 Reply Last reply
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            • O Offline
              O Offline
              oldman
              wrote on last edited by
              #26

              Have the original powervalve fortunately, the manual is. 4 or. 04 difference I think from memory, Will be checking when assembling .

              D 1 Reply Last reply
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              • O oldman

                Have the original powervalve fortunately, the manual is. 4 or. 04 difference I think from memory, Will be checking when assembling .

                D Offline
                D Offline
                DTR+NSR
                wrote on last edited by
                #27

                My understanding is the 1988 has the BN barrel and slightly longer stroke 0.5mm or something. 88 on wards they had slightly bigger bore and shorter stroke. Think if you mix and match parts you can end up with a 135cc or similar.

                1 Reply Last reply
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                • CalumC Calum

                  @oldman Yeah this.

                  The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.

                  It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.

                  As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!

                  O Offline
                  O Offline
                  oldman
                  wrote on last edited by
                  #28

                  @Calum said in 1988 bike:

                  @oldman Yeah this.

                  The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.

                  It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.

                  As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!

                  Hello Calum,What's the difference with the powervalve? Have measured and dry assembled and seems no different than one that came with bike, bar original has no grooves for seals and diamond style pulley shaft on end? Frame back but waiting for rack, grab rail, footrest hangers, suspension spring, etc.

                  CalumC 1 Reply Last reply
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                  • O oldman

                    @Calum said in 1988 bike:

                    @oldman Yeah this.

                    The manual specifies both the bore and stroke for the 3BN, I'm sure. I don't have it to hand.

                    It is so minor I doubt it'll be too much of a problem. Powervalves are not interchangeable though.

                    As said, doubling up on base gasket will do the trick. My worry is that the con rod is designed to stretch and compress, how close will it be at 12k RPM is anyones guess!

                    Hello Calum,What's the difference with the powervalve? Have measured and dry assembled and seems no different than one that came with bike, bar original has no grooves for seals and diamond style pulley shaft on end? Frame back but waiting for rack, grab rail, footrest hangers, suspension spring, etc.

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

                    @oldman I must be thinking 4FU and 3MB.

                    One of them didn't fit.

                    Always Originate, Never Pirate!

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                    • O Offline
                      O Offline
                      oldman
                      wrote on last edited by
                      #30

                      OK, thanks Calum. Replacement shock arrived and it's worse than the one I need to replace sadly. Lower ball joint corroded and worn and corrosion on plunger shaft has damaged the seal, very little damping going on. Will keep looking for a decent one.

                      CalumC D 2 Replies Last reply
                      0
                      • O oldman

                        OK, thanks Calum. Replacement shock arrived and it's worse than the one I need to replace sadly. Lower ball joint corroded and worn and corrosion on plunger shaft has damaged the seal, very little damping going on. Will keep looking for a decent one.

                        CalumC Online
                        CalumC Online
                        Calum
                        wrote on last edited by
                        #31

                        @oldman FFS :@

                        Always Originate, Never Pirate!

                        1 Reply Last reply
                        0
                        • O oldman

                          OK, thanks Calum. Replacement shock arrived and it's worse than the one I need to replace sadly. Lower ball joint corroded and worn and corrosion on plunger shaft has damaged the seal, very little damping going on. Will keep looking for a decent one.

                          D Offline
                          D Offline
                          dan28
                          wrote on last edited by
                          #32

                          @oldman said in 1988 bike:

                          OK, thanks Calum. Replacement shock arrived and it's worse than the one I need to replace sadly. Lower ball joint corroded and worn and corrosion on plunger shaft has damaged the seal, very little damping going on. Will keep looking for a decent one.

                          look for a shock from a newer bike they have a white spring an fit on the 89 model

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                          • O Offline
                            O Offline
                            oldman
                            wrote on last edited by
                            #33

                            Finally got a decent shock, waiting for powdercoating to return (have frame back though)so I can start rebuild. Seller of faulty shock not responded yet to return for refund, but covered via PayPal. Looked at getting a new indicator switch gear assembly and they are over £150. Put that on the wish list with everything else. Photos will be posted when there is something to show!

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                            1
                            • O Offline
                              O Offline
                              oldman
                              wrote on last edited by
                              #34

                              Powdercoating back bar 2 items that should be here later this week, now where did I leave the assembly instructions????20190623_231148-460x818.jpg

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                              • CalumC Online
                                CalumC Online
                                Calum
                                wrote on last edited by
                                #35

                                Haha that looks fantastic!

                                Always Originate, Never Pirate!

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                                • O Offline
                                  O Offline
                                  oldman
                                  wrote on last edited by oldman
                                  #36

                                  Thought I had most of it but still missing plenty of bolts and fixings. Returned some of the plating, looked bad to be honest. On top of that rats have chewed the brake pipes on my van so that's being recovered on a flatbed truck tomorrow, revenge for shooting one. Started off with the abs light coming on, took to garage and sensor wire cut. Went to take it for repair and no brakes at all, other rear sensor wire chewed and brake fluid squirting out of chewed hose. How lucky am I

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                                  • O Offline
                                    O Offline
                                    oldman
                                    wrote on last edited by
                                    #37

                                    Progress has been slow, mainly due to the weather this weekend. But important parts are coming back so I will try and press on (especially if it rains!) Attended vjmc show Sunday then a decent ride with both the red and white dt's, my blue 125mx and an rd350lc. I can still taste the 2 stroke oil being at the back (I was riding the 125mx). Covered approx 70 miles without mishaps, bit I so want a rd350, sounds brilliant.20190701_195432-460x818.jpg 20190701_195442-819x461.jpg 20190701_195501-819x461.jpg

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                                    • O Offline
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                                      oldman
                                      wrote on last edited by
                                      #38

                                      IMAG0063-1612x1209.jpg

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                                      • O Offline
                                        O Offline
                                        oldman
                                        wrote on last edited by
                                        #39

                                        Refurbed oil pump arrived back this morning, hard to believe it's almost 31 years old, perfect job!
                                        20190706_103957-460x818.jpg 20190706_104017-460x818.jpg

                                        Powdercoated spring collected yesterday as well, so can crack on a bit.

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                                        • O Offline
                                          O Offline
                                          oldman
                                          wrote on last edited by
                                          #40

                                          Reassembled shock ready for action

                                          20190706_154859-819x461.jpg

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