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    How do you break in your fresh re bores

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    • declan
      declan last edited by

      How many miles/ hours do you guys spend breaking in your fresh piston and re bore?

      Darty 1 Reply Last reply Reply Quote 0
      • Darty
        Darty @declan last edited by

        @declan Around 500 miles -

        Just concentrate on getting a few heat cycles in first,

        then low to midrange running only.

        It's about wearing in the Piston Rings to the bore not the piston.

        declan 1 Reply Last reply Reply Quote 1
        • declan
          declan @Darty last edited by

          @Darty 500 miles seems overly excessive

          Darty 1 Reply Last reply Reply Quote 0
          • Darty
            Darty @declan last edited by

            @declan Why?

            declan 1 Reply Last reply Reply Quote 0
            • declan
              declan @Darty last edited by

              @Darty well the heat cycles are important I get that but 500 miles what if it's not an on road bike it would take me all year to break it in

              1 Reply Last reply Reply Quote 1
              • Calum
                Calum last edited by

                Ahh well you're posting this question on a DT forum.

                I agree with @Darty 500 miles of different riding styles with the first 100 miles being gentle.

                On a DT it's about reliability.

                On a crosser it's about not glazing the cylinder walls and losing compression. So would you really break an engine in on a offroad bike. Probably not.

                1 Reply Last reply Reply Quote 1
                • Darty
                  Darty last edited by

                  It has to be said,

                  It's about the Clearances, they are not like your MX engines...

                  You go out with some full beans with fresh rings and you will begin to melt the edge of them before they have worn,

                  Excess heat from friction will score the bore, and you will seize, I've seen a few seize within 50 miles!

                  It's worth taking the time with it, it should last over 10,000 miles after that!?

                  You can't really run these in unless it's under load either, Steel liners and so...

                  Shame, good ol' YZ engine can be run in on the stand, in the garden...

                  NINJA 1 Reply Last reply Reply Quote 1
                  • NINJA
                    NINJA @Darty last edited by

                    @Darty said Shame, good ol' YZ engine can be run in on the stand, in the garden...

                    Man that's insane, so MX bikes are pretty much low use then rebuild em? I guess that's why their usage is measured in hours then???

                    declan Darty 2 Replies Last reply Reply Quote 0
                    • declan
                      declan @NINJA last edited by

                      @CYBER-NINJA well they don't have clocks so they only have hour meters

                      1 Reply Last reply Reply Quote 0
                      • Darty
                        Darty @NINJA last edited by Darty

                        @CYBER-NINJA 120 hours Max for an Enduro 125,

                        but if you're a racer, more like 35-50 hours

                        Mx bikes can last 5 hours sometimes 😂

                        1 Reply Last reply Reply Quote 1
                        • Calum
                          Calum last edited by

                          I mean a fresh piston rebore. 500 is a lot. If it was full rebuild then I would err on the 500 side. As long as you give enough miles for the rings to bed into the cylinder walls and don't glaze them you will be fine.

                          declan 1 Reply Last reply Reply Quote 0
                          • declan
                            declan @Calum last edited by

                            @Calum well as you might know I'm yet to ride mine but the shop has to bore 1 and a half mil I think not fetched it yet but quick side question for you will this add any torque or power now I'm not asking will it be on the back wheel in every gear I'm asking if it would make a difference no matter how small just curious

                            Calum 1 Reply Last reply Reply Quote 0
                            • Calum
                              Calum @declan last edited by

                              @declan No.

                              declan 1 Reply Last reply Reply Quote 1
                              • declan
                                declan @Calum last edited by

                                @Calum figured so thanks

                                1 Reply Last reply Reply Quote 0
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