A 45 Johnson

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  • November 20, 2015 at 1:27 pm #3015
    tji
    Participant

      I came across a A45 Johnson and was wondering if someone could explain the purpose of the compression relief valve on the left cylinder and how to use it. Thanks in advance. TJI

      November 20, 2015 at 4:06 pm #27420
      Tom
      Participant

        US Member

        The compression release closes off the intake port to the motor, which forces more air/fuel mix to the other cylinder. In cold weather, this might help keep the fuel from condensing out, and actually getting to the cylinder. The compression release also opens up the cylinder to the atmosphere, making it easier to crank over the motor.

        I have owned and run A, K, S, and P motors with rotary valves, and never needed to use them. Choke the motor, bounce it a couple of times, open the choke, and start.

        Tom

        November 21, 2015 at 12:15 am #27444
        Mumbles
        Participant

          Will my dealer still honor these prices?

          November 21, 2015 at 1:08 am #27448
          cajuncook1
          Participant
            quote Mumbles:

            Will my dealer still honor these prices?

            😆 😆 😆

            November 22, 2015 at 12:42 am #27489
            george-emmanuel
            Participant

              US Member

              You found a Johnson dealer???? Wow!

              November 22, 2015 at 2:19 am #27493
              tji
              Participant

                Thanks for the info on the A45. Looking at the picture I can see how it works. My motor is missing a lot of pieces, any additional info on this motor would be greatly appreciated. Thanks, TJI

                November 22, 2015 at 2:38 am #27497
                Randy in Tampa
                Participant

                  not sure but this may help 😉 https://drive.google.com/open?id=0B1I_8 … EhyT1FNRFU

                  November 22, 2015 at 6:41 am #27498
                  1946zephyr
                  Participant

                    Not sure if I can help much, but that particular model is the last year of the opposed twin A model Johnson built. In 1930, the model became the A-50 (4hp) and it was an alternate firing twin with the revolutionized "under/over" engine design, which is still in use today. By 1939, the model had become a 5hp. The 1938 was the 4.2hp and the last model year with the "all cast iron" cylinder assembly. 1939 was aluminum with cast iron cylinder linings.
                    Believe it or not, that is also the model that the old TD, CD and all the other 5 and 6hp Johnson outboards derived from.
                    The LT became the TD and the TD became the TN and then the CD went from there.
                    Enjoy that old classic. You will be amazed at how easy it is to run and how reliable it is. The old Johnson A model was the motor that made the definition on "old outboard reliability"

                    November 22, 2015 at 7:58 pm #27517
                    Buccaneer
                    Participant

                      US Member

                      I just acquired an A45 power head, so it was nice to learn
                      a little about it! I see it has "said" compression relief
                      on starboard cylinder. Now I just need a lower unit
                      and gas tank 🙂

                      Attachments:

                      Prepare to be boarded!

                      November 22, 2015 at 9:55 pm #27527
                      dmbono
                      Participant

                        I like my A-45. I often use the compression release to start it, makes pulling rope a bit easier. Very reliable.

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