Crankcase Cracks (Crazing?)

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  • caltrop
    • Jan 2026
    #1

    Crankcase Cracks (Crazing?)

    So I started cleaning up the interior of my crankcase and I noticed what appears to be a rather big issue. All inside the front end of the lower half is a network of what appear to be cracks. At first I thought it was just in the baked-on oil film, but then I realized it was actually in the metal.



    Now I swear I'm not crazy, but the lines are actually formed by raised material. I've pentuple-checked with naked eye, jewelers loop, and pocket microscope, and I'm sure that most of the lines are actually raised, not indented like you'd expect cracks to be. I'm guessing there actually are cracks and that material has just been pushed up by the compression of these cracks, but I was hoping to get some other folk's opinions. I've also found some bits of metal embedded in the surface in some areas around there, and a few instances of small bits of material chipped out of the surface.

    I'm guessing this all related in some way to my damaged bearings, and I take it this case is a goner. Still, I'm trying to figure out what the hell happened to this thing.
    Tags: None
    • 1980GS1000E
      Forum Sage
      Past Site Supporter
      • Aug 2007
      • 1664
      • San Diego, California, USA
      #2
      Not to worry. Every case will exhibit some of this. The cracks are from the casting process and are surface only. They are formed by the different cooling rates of the mold and the metal during case manufacture. If they bother you, just sand them out.
      Last edited by 1980GS1000E; 08-11-2012, 08:24 PM.
      Current Rides: 1980 Suzuki GS1000ET, 2006 H-D Fatboy, 2021 BMW K1600B

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        • Nessism
          Forum LongTimer
          GSResource Superstar
          Past Site Supporter
          Super Site Supporter
          • Mar 2006
          • 35784
          • Torrance, CA
          #3
          Agree. No worry.
          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

            Comment

            • JEEPRUSTY
              #4
              My heads innerds have these too.

                Comment

                • caltrop
                  #5
                  Alright, very good to know. I had thought it might be an artifact of the casting process, but I really didn't want to get my hopes up.

                  Any advice for telling this stuff from actual cracks? There are some places I'm still worried may actually be cracked. Should I just sand it a little and see if it still looks that way?

                    Comment

                    • mustangflyr
                      Forum Mentor
                      • Oct 2004
                      • 308
                      • Green Cove Springs , FL
                      #6
                      Originally posted by caltrop
                      Alright, very good to know. I had thought it might be an artifact of the casting process, but I really didn't want to get my hopes up.

                      Any advice for telling this stuff from actual cracks? There are some places I'm still worried may actually be cracked. Should I just sand it a little and see if it still looks that way?
                      Take it to a machine shop and they can do a dye test that will reveal if they're cracks or not.
                      1980 GS1000E

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