Home Forum Ask A Member 1940 Johnson HD-15 Magneto testing

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  • #60567
    joesnuffy
    Participant

      Time to give it some thought and take a break. If your like me heck I will wake up with the answer. I wonder if bakelite is off it would be nice to know for sure. From what I have read your a great mechanic with carb tuning skills. Looking at everything knowing your good at repairing outboards something is off. I can see looking at pics you have attention to detail.

      Let us know when you figure it out I know you will.

      Joe

      #60569
      Buccaneer
      Participant

        US Member

        Thanks Joe, perhaps someday I’ll stumble upon another
        one of these units and can compare or switch parts.
        Forgot to mention prior regarding the points cam
        that it’s ground into the crankshaft, therefore it’s
        not upside down!

        Prepare to be boarded!

        #60572
        Buccaneer
        Participant

          US Member

          Just found the magneto parts diagram that shows a drawing
          on the inside of the flywheel. Makes me feel better that
          I have the bakelite plate installed correctly.


          Attachments:

          Prepare to be boarded!

          #60578
          garry-in-michigan
          Participant

            Lifetime Member

            If you only have one lobe, you need a magneto with two coils. If it is original and ran before, you have two lobes. If you got it apart in a box, all bets are off. . . 😆

            #60579
            Buccaneer
            Participant

              US Member

              HD-15 crank has two lobes ground in it, so
              all is well there!

              Prepare to be boarded!

              #60585
              joesnuffy
              Participant

                That’s good to know bakelite and tab is in correct position and you weren’t getting double fire that’s also a good thing. Something weird going on might not be ignition.

                Joe

                #60652
                joesnuffy
                Participant

                  I just can’t get this motor out of my mind. lol

                  I downloaded your video with youtube downloader and played it back slow speed several times with VLC media player.

                  I noticed that you have the speed lever pretty high. When I watch video motor seems to slow down then try and pick-up to high speed but just can’t make the transition to wot. It does this several times before it finally dies.

                  When I rebuilt my sea doo 2 stroke jet ski’s like 15 years ago they also have a rotary valve. The crankcase was suppose to be pressure tested using a leakdown test to check crankshaft seals. 2 of those seals are mounted to the center of crank and crank has to be disassembled and pressed back together to change them but you can change the outer 2 easily when rebuilding motor. Those seals are very important with a rotary valve and the case can’t leak either where it clam shells and bolts together. if they do leak you get a motor that won’t run correctly.

                  I wonder if when it was running if you could mist some 2 stroke fuel mix into the throat of carb and see if motor speed increases to wot or close. I have also heard people using some propane gas from an unlit propane torch. By doing this it might let you know if top and bottom seals are doing their job. I don’t know if that motor has an oil slinger on top instead of seal. It might also let you know if perhaps case might be leaking. Since you have motor back together wouldn’t be hard to check.

                  I also got all my electronics to build red atoms yesterday. I would be glad to mail you a couple at no charge once I build them. You could try one in that engine if it won’t work then you could put them into another 2 cylinder omc motor and see what you think about them.

                  I also noticed looking at the pics you didn’t put new wires from coil to brushes. Mumbles looks like he did. That one wire on the left in your picture going from the coil to brush looks pretty close to the coil laminate do you think fire could be jumping there??

                  Hope that helps,
                  Joe

                  Getting ready to go camping this weekend happy 4th!!! to everyone

                  #60663
                  Buccaneer
                  Participant

                    US Member

                    Joe, the HD has been drained of fuel and put back on the
                    rack for now.
                    This 1940 Johnson has "no" crank seals. I did lap the
                    crankcase halves to true up the sealing surfaces, and tighten the crank
                    bearings on the crankshaft, normally I "no-no" I’m
                    guessing, but it actually made the crank bearing halves
                    more "round", and with less clearance. Also I installed
                    new rings. Compression was in the low 60’s when I checked
                    it originally after putting it back together.

                    I didn’t want to take the chance of un-soldering the wires
                    to the coils, but I did coat the old wires with Super Corona Dope.
                    I seen no signs of "burn marks" or arcing anywhere on the mag
                    in the many times I had it apart. 🙁

                    I like your idea of using propane. Maybe it would tell me if
                    the crank case halves are sealed properly.
                    I know that back in the day, ether worked good for checking
                    crankcase seals leaking on the clutch end of snowmobiles!

                    Some day maybe I’ll take you up on the red atom modules, but
                    I should probably try them on a normal running engine first
                    to know if they’d work for me, lol.

                    Hot and heavy into my new to me, but sad looking 52 Fleetwin.
                    I will not forget the little Johnson….. I hate to be defeated!
                    Thanks, Bucc

                    Prepare to be boarded!

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