Tight rings

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  • April 29, 2015 at 10:43 pm #1371
    Goman
    Participant

      I put some new rings on a Johnson A-25. I checked the gaps and filed for the pin accordingly. I had to lightly tap the top of the cylinder with a hammer and board to get it to go. I see on you tube that other types of small 2 strokes the cylinder slides on quite easily. I did this last year to a similar motor and it seems to doing ok but I’ve only run it about an hour at low to mid speed. This motor I’m working on seems to be a tad tighter than that one when turning by hand with the flywheel. I was wondering with a slow break in speed if the rings and cylinder will "adapt" to each other. It’s such a pretty thing I’d hate to make a wall hanger of it. 😮 As always thanks for your help.

      Glen

      April 29, 2015 at 11:31 pm #15042
      frankr
      Participant

        US Member

        I guess I don’t have to tell you that it is considered standard practice to try the rings in the cylinder before putting them on the piston. Oh well, too late now. If they truly are tight in the end gaps, It would be a stroke of luck if they wear in enough.

        April 30, 2015 at 12:02 am #15050
        Goman
        Participant

          The rings were placed in the cylinder first to get the proper ring gap. I’ve read in the old forum where another member had this same type of problem with a too thick of a ring in the same type of motor. Nothing was mentioned of a remedy.

          April 30, 2015 at 2:07 am #15075
          garry-in-michigan
          Participant

            Lifetime Member

            I would stick a sheet of sticky back 600 grit wet or dry (carburundum) paper to a sheet of plate glass or a large polished marble floor tile in order to polish both sides of the piston rings. Go in a figure eight motion to be sure of an even coverage. It should give you another thousandth of clearance.

            . . . . . 😉

            April 30, 2015 at 11:19 am #15091
            Goman
            Participant

              Thanks Garry. The width of the rings fit in the lands fine. It’s the thickness of the ring that’s keeping it tight. I took an old ring and placed it in a wood vice and used a dremel with a flap wheel and reduced the thickness a couple of thousands. I will probably try that route and look for a better ring source next time.

              April 30, 2015 at 12:49 pm #15095
              The Boat House
              Participant

                • This reply was modified 6 years ago by The Boat House.
                • This reply was modified 3 years, 9 months ago by The Boat House.
                April 30, 2015 at 6:24 pm #15115
                garry-in-michigan
                Participant

                  Lifetime Member

                  I had an "L" shaped tool with a carbide tip that was designed to remove carbon from the ring grooves. (The factory said to use a broken piston ring) With pressure you could make the grooves deeper. My preference would be to thin the rings. It must be done in a way that ensures uniformaty.

                  April 30, 2015 at 7:45 pm #15125
                  Goman
                  Participant

                    If I did my home work from the get go I would have realized the rings would give me a problem before I started. Lesson learned. As tight as it is right now I don’t think it would pull start with a cord. I’d rather fool with the rings as to mess with the cylinder too much. I had pretty good even results using the flap wheel to remove material from the inside of the ring. Thanks again.
                    Glen

                    May 9, 2015 at 3:58 pm #15583
                    jimparrott
                    Participant

                      US Member

                      If the rings are too thick they will indeed be too tight or not springy enough. If you have a lathe available you can make a fixture to hold the ring in its compressed state and cut the ID as desired. I have just used a pipe with a step cut in the end of it and superglued the ring in place to turn it making light cuts. The superglue holds great and is easily released with a light tap. Hope this helps.

                      Jim

                      May 9, 2015 at 10:11 pm #15616
                      Goman
                      Participant

                        I went ahead and took off two or three thousands with the flap wheel. Before I started I noticed the thickness of the rings varied up to a couple of thousands when measuring around the ring anyway. It helped. I guess I’ll know about performance wise soon enough. May have to get a picture frame for it. 🙂

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