1924 2hp BNL Johnson runs rough

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  • October 14, 2024 at 7:26 am #291488
    The Boat House
    Participant

      Looks like the pistons could be hitting the ground electrodes on the sparkplugs.Tubs

       

       

       

      October 14, 2024 at 1:45 pm #291490
      joecb
      Participant

        US Member

        Lots of good suggestions here for sure. I too am inclined to think something electrical. My default “gremlin” is always the capacitor. I read that you had already changed the cap.  Are you sure that the new one is really good? If it is an old style paper and foil cap they do age out. Do you have a way to stress test the cap? .. a tester that applies significant voltage, something upwards of 100 volt?  Can you source a modern mylar capacitor about .22  to .4 mf range? Try that.

        Joe B

        PS, other thought… points bouncing  from weak spring?

        October 15, 2024 at 4:28 am #291503
        Monte NZ
        Participant

          International Member

          Success at last!

          I fitted the new condenser and gave the points a complete overhaul………the contacts were like a couple of mirrors after I had finished them. I also checked that the timing was correct.

          I then found that with this work done, I could now flick the motor over by hand and get an excellent spark, whereas previously I had to turn the motor over with the cord.

          The motor started on the second pull and ran well compared to performance prior to the installation of new condenser and points overhaul. but  I still think the motor is running a little bit rough…….your comments would be appreciated.

          I have provided a link to two video clips of the motor running so you can see the improvement in performance………as the gearbox is still to be installed, I used my hand to add load to the motor.

          https://photos.app.goo.gl/mePX2XtFfb6KWY319

          Thanks very much once again everyone for all your help.

          Monte NZ

          October 15, 2024 at 5:10 am #291504
          Monte NZ
          Participant

            International Member

            Success!

            Today I fitted the new condenser and gave the points a thorough service  …….the contacts look like mirrors!

            I am very pleased to report that the motor started on second pull and ran much better……..however, I still feel that the motor doesn’t run as well as the ones I have been watching on You Tube.

            Interesting to note that prior to starting the motor I noticed that I can now flick the motor by hand and get a good spark, whereas previously I had to use the cord.

            I have provided a link to two video clips of the motor running and would very much appreciate any comments.

            https://photos.app.goo.gl/NtyTUMru5EdkbVKF8

            Thanks very much once again all of you for your help!

            Monte NZ

            October 15, 2024 at 5:20 am #291505
            Monte NZ
            Participant

              International Member

              Sorry everyone, it looks like the photo I spoke about hasn’t shown in my last post!

              Here it is hopefully!

              https://photos.app.goo.gl/Ht6WFCazQg39dyAv9

              Monte NZ

              October 15, 2024 at 5:36 am #291506
              Monte NZ
              Participant

                International Member

                Hi All

                I appear to be having computer problems, so my apologies for my confusing posts!

                Monte NZ

                October 15, 2024 at 11:15 am #291519
                stanley
                Participant

                  US Member - 2 Years

                  In the video that shows it running the best,it looks pretty typical to me.I have several that I run often.

                  October 15, 2024 at 11:18 pm #291552
                  The Boat House
                  Participant

                    looks to be a nice example and it couldn’t be in a better place. Now that you have it running as it should, you’ll find your 100 year old motor to be very reliable. Its been almost 10 years since this discussion board came on line and it still having issues. Tubs
                    October 16, 2024 at 11:23 am #291555
                    The Boat House
                    Participant

                      I measured a plug from a 1931 model OA-55 I plan on restoring this winter. I think you should check to see that the sparkplugs aren’t making this mark. Tubs

                      October 17, 2024 at 4:41 am #291582
                      Monte NZ
                      Participant

                        International Member

                        Thanks Joecb, you were certainly on the right track regarding  the condenser possibly being a problem.

                        Stanley, thanks very much for your reply. your comments from your experience have made  me feel a lot happier!

                        Thanks very much too Tubs for your  comments. As you can imagine, I’m very much looking forward to having some fun with it in the lake.

                        Regarding the series of dimples on the piston below the spark, I thought too, that the electrode on the plug was responsible, but when I measured the gap with my depth gauge there was still 3/8 inch gap below the plug and the only thing that I can think of, is that someone, many years back, accidently installed a long reach plug.

                        One modification I did, was to bore through the shaft so that I could use a split pin rather than the original setup of two nuts to hold the prop. When drilling I discovered that I was dealing with hardened stainless steel. Needless to say, it  took ages to drill the hole and I lost count of the number of times I had to sharpen the drill! I then made a brass prop nut as used on later motors, which I think looks better and is more practical.

                        One problem I forgot to mention, is that a few days after finishing the tank painting I noticed several paint  blisters pop up about half way up the back where the weld line is.

                        I discovered small pin holes which I thought must have occurred during manufacture. I  bored the holes with my Dremel and sealed them with JB Weld…….needless to say I was very pleased to find the holes before applying the tank decal!

                        I have provided a link to shots of the prop modification and the pinholes in the tank.

                        https://photos.app.goo.gl/MZZ7eJq2Acp5QsBX8

                        https://photos.app.goo.gl/U6oHqXS1YmFKVG7c6

                        Thanks all of you for your help……much appreciated!

                        Monte NZ

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