Old Johnson

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  • April 21, 2017 at 2:46 am #6802
    labrador-guy
    Participant

      US Member

      Hi guys, what can you tell me about a KD15 Johnson. I just picked one up and I am lost but I am learning! This motor is complete and needs a bunch of cleaning. Peter Hunn’s outboard bible tells me it’s a 1941 model. Must be one of the first vertical twins that Johnson built. Maybe a precursor to the QD series? Rewind is now working after much fusing with those wave washers. I have no spark. Getting the flywheel off was a bugger. I found three of those 1/4x 24 threaded bolts! I read about them in another tread. I used the original rewind cog bolts to get a pry on the flywheel and managed to get it off. Strange condensers, strange rotary valve system. Is there a seal in the middle of the cylinders? How does this motor maintain crankshaft pressure? Gonna test the coils tomorrow. Any info or insight on this puppy will be appreciated.

      dale

      April 21, 2017 at 3:02 am #56455
      kevinrude
      Participant

        Well, LG, I have absolutely no insight for you, but I do have two of these motors in the garage, so I will be watching this thread closely. Good luck! I think JoeCB fixed up one of these a few years back, and that guy is a better mechanic than I can ever hope to be. Maybe he’ll be able to help you out?

        April 21, 2017 at 3:16 am #56456
        wedgie
        Participant

          😉

          http://www.austinsailor.net/manuals/manuals.html

          April 21, 2017 at 4:03 am #56458
          crosbyman
          Participant

            Canada Member - 2 Years

            http://boatinfo.no/lib/johnson/manuals/ … on.html#/0

            the book of knowledge page 97 covers a bit on carburation of KD’s ….other sections not to rich with info

            Joining AOMCI has priviledges 🙂

            April 21, 2017 at 4:43 am #56460
            Mumbles
            Participant

              I think the honor of being the first alternate firing Johnson would have to go to the 1930 A-50 and K models. They’d been around a few years before your motor was built and yes, your 71 lb. 9.8 horsepower KD-15 motor was the forerunner to the QD series and calls for an 8:1 fuel mix using 40W oil. AeroShell Oil 80 or AeroShell W80 aviation oils are both SAE 40 W oils. Two rings on the large rotary valve seal the crankcase. The original square condensers were rated at .22 uF and the Champion 5MJ plugs are set a .030" and the points at .020". The magneto is kind of unique with a separate coil for each cylinder. You say you pried the flywheel off? It would be better to use a puller to avoid risking any damage to the flywheel.

              Attachments:

              April 21, 2017 at 10:51 am #56464
              labrador-guy
              Participant

                US Member

                Yup that is the baby! Mine does not have that kill button. It has two metal tabs that look like they contact the housing when the go lever is moved all the way to the left. What is going on with the exhaust damper? A leaver from the carb controls, opens a metal washer on the underside of the exhaust duct. Maybe exhaust relief? Your motor has a cutout on the muffler. Mine has a bolted on cover. Were these motors racers? Plenty thick oil ratio, maybe trying to seal the crankcase? This motor is a learning experience for me. I made an offer and it followed me home!
                thanks dale

                April 21, 2017 at 10:54 am #56465
                labrador-guy
                Participant

                  US Member

                  Try this!

                  Attachments:

                  April 21, 2017 at 2:25 pm #56473
                  garry-in-michigan
                  Participant

                    Lifetime Member

                    The racing model had roller bearings on the crankshaft and top, bottom seals, side draft carburetor and a slimmer gearcase with a higher gear ratio. Also an open exhaust and higher compression ratio with two ring pistons. . . 😀

                    April 21, 2017 at 5:03 pm #56483
                    Doug Wilson
                    Participant

                      US Member - 2 Years

                      I have both A-50 and K-50 motors the original rectangular condensers you are not going to find. Mid 60s chevy condensers work just have to drill and tap a hole to mount them where the originals were. I made little covers to go over the bottom of the mag plate to cover the modern ones I put in there. They work fine neither motor has given me any issues since I put them in.
                      Doug

                      Doug

                      how is it motors multiply when the garage lights get
                      turned off?

                      April 21, 2017 at 7:07 pm #56491
                      mercuryman
                      Participant

                        I have a KA38 I recently acquired and can’t get the flywheel loose. I have pulled the puller as tight as I dare, applied heat and penetrating oil and tap on puller bolt, won’t budge. If I pull real hard what will break first, bolt or flywheel ? I have cleaned the points through the little window on flywheel and got the motor running good maybe I should let it alone.

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