Top end rebuild break in

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  • ehkmcveh
    • Feb 2026

    #1

    Top end rebuild break in

    Whats the proper way to break in a fresh top end, piston rings/honed cylinder/ lapped valves. Only had it started for 5 min but hearing different methods for the break in.
  • Nessism
    Forum LongTimer
    GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    • Mar 2006
    • 35790
    • Torrance, CA

    #2
    Just go ride. Use a good bit of throttle but no redline and no lugging for a while. Follow up with a valve clearance check and torque the head after a hundred miles or so. If the head nuts are loose then follow up in another hundred miles until the nuts stop loosening. Some guys advocate the Moto Tune break in method. That's fine and all but I don't think a strict redgment is necessary.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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    • ehkmcveh

      #3
      Originally posted by Nessism
      Just go ride. Use a good bit of throttle but no redline and no lugging for a while. Follow up with a valve clearance check and torque the head after a hundred miles or so. If the head nuts are loose then follow up in another hundred miles until the nuts stop loosening. Some guys advocate the Moto Tune break in method. That's fine and all but I don't think a strict redgment is necessary.
      Ah ok thanks ed, Just a little gun shy right now because when I idle the bike and it the bike warms up, there is some noticeable smoking coming from the engine. Appears from the head gasket. Wonder if it just needs a re-torque.

      I have about 5 min of start time on the new top end, my buddy is telling me to just ride it and see what happens

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      • ehkmcveh

        #4
        No smoke coming out the pipe though, which is a mystery if there is smoke coming out of the head gasket????

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        • Nessism
          Forum LongTimer
          GSResource Superstar
          Past Site Supporter
          Super Site Supporter
          • Mar 2006
          • 35790
          • Torrance, CA

          #5
          Did you spill some oil on the engine that's starting to burn off?
          Ed

          To measure is to know.

          Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

          Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

          Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

          KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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          • Guest

            #6
            Rebuilt motors always smoke for awhile. If it is puffing smoke out the head gasket then you'll be doing the job again.

            Comment

            • ehkmcveh

              #7
              yeah its puffing out a bit I think. Going to try a re-torque today.
              Then maybe take er for a ride.

              Just read that guys re-use the head gasket all the time with no issue
              Just weird that its puffing out the gasket and not the exhaust pipe

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              • ehkmcveh

                #8
                Originally posted by Nessism
                Did you spill some oil on the engine that's starting to burn off?
                No I can see the smoke billowing up between carb 4 and 3. When I move my flashlight down it appears to be coming out of the head gasket... appears

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                • Guest

                  #9
                  You reused your head gasket?

                  Comment

                  • ehkmcveh

                    #10
                    yeah I did

                    Comment

                    • ehkmcveh

                      #11
                      Head bolt torqueing... The service manual says between 25.3 and 29 ibs-ft.
                      you are suppose to step in up... say 10, then do the sequence bolt pattern.. then 20... then final

                      Has anyone gone a little tighter just to get a better seal? I have read some guys going up to 40,

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                      • JTGS850GL
                        Forum Guru
                        Past Site Supporter
                        • Aug 2013
                        • 9735
                        • GA

                        #12
                        Originally posted by ehkmcveh
                        yeah I did
                        I'd bet you'll be pulling the head again. Pick up an OEM head gasket and you wont be doing it again anytime soon.
                        http://img633.imageshack.us/img633/811/douMvs.jpg
                        1980 GS1000GT (Daily rider with a 1983 1100G engine)
                        1998 Honda ST1100 (Daily long distance rider)
                        1982 GS850GLZ (Daily rider when the weather is crap)

                        Darn, with so many daily riders it's hard to decide which one to jump on next.;)

                        JTGS850GL aka Julius

                        GS Resource Greetings

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                        • ehkmcveh

                          #13
                          Originally posted by JTGS850GL
                          I'd bet you'll be pulling the head again. Pick up an OEM head gasket and you wont be doing it again anytime soon.
                          Lol..... more than likely..

                          Gonna try the re-torque first..

                          Anyone with try with a little tighter torques spec?

                          Comment

                          • ehkmcveh

                            #14
                            RE-tightened, started at 10 ft-ibs, tightened in the proper sequence... then 18, then 26, then 32. Boom No smoke

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                            • JTGS850GL
                              Forum Guru
                              Past Site Supporter
                              • Aug 2013
                              • 9735
                              • GA

                              #15
                              We'll see how long it lasts. Hopefully for a long time.
                              http://img633.imageshack.us/img633/811/douMvs.jpg
                              1980 GS1000GT (Daily rider with a 1983 1100G engine)
                              1998 Honda ST1100 (Daily long distance rider)
                              1982 GS850GLZ (Daily rider when the weather is crap)

                              Darn, with so many daily riders it's hard to decide which one to jump on next.;)

                              JTGS850GL aka Julius

                              GS Resource Greetings

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