1928 Johnson "race" motor

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  • adam1961

    Canada Member - 2 Years
    Replies: 366
    Topics: 88
    #69909

    The R designation on the model numbers began in 1928 with the introduction of the 40 series engines. In 1928, the racing engines did not have significant external differences from the service models (ex P40 vs PR40). The changes on the racing models for 1928 included bearings in place of bushings on some late production motors and other internal changes.

    The racers changed significantly in 1929 when the 45 series was introduced. The mid sections got shorter, the gear case was more streamlined, carbs had velocity stacks rather than shielded intakes and the exhaust was above water. The 1929-32 models were similar. There were more refinements after 1933 when the 65 series was introduced.

    Although the 1928, 40 series motors are not what most people would think of as a racer, they are part of the evolution of boat racing and are an important part of my collection when it comes to showing the evolution of Johnson motors.


    Anonymous

    Replies: 251
    Topics: 33
    #69922

    Finally heard back from my friend who’s talking to a guy who’s friends of the guy with the motor. Very frustrating!!! Turns out it’s a KR-40. Trying to cut out all the middlemen so I can take a look at it. Still no more pictures. Hopefully more to come.
    Kirk


    adam1961

    Canada Member - 2 Years
    Replies: 366
    Topics: 88
    #69923

    The KR-40 is still a neat motor. It will look just like the K-40. I thought I had found one a few years back, but the serial number on the rope plate did not match the one on the crankcase, so no way to know if it was a real KR without opening it up. As someone who is interested in Johnson motor history, I think that is a neat motor. If you are looking for speed, the KR series really took of with the introduction of the KR55 as an alternate firing twin.


    spike


    Replies: 37
    Topics: 16
    #69942

    Thought I would show a couple pics of my numbers matching (80750-c) 1928 KR-40.


    Attachments:


    squierka39

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 610
    Topics: 34
    #69943

    The muffler is very different on the one in question and the numbers matching one above. Any thoughts on that? It looks bigger like the PR maybe, but sellers says it’sa KR. Interesting.


    spike


    Replies: 37
    Topics: 16
    #69946

    Squier, Can’t say for sure about the muffler but I have heard is they used the older round can type for the early 28’s and went to the new box type as used on the 1929 K-45 for the late 28’s. My serial 80750 puts it in the middle of the 1928 production so who knows? Hopefully someone with more knowledge will be able to help say for sure.


    Mumbles


    Replies: 5764
    Topics: 298
    #69947

    I’m trying to find my Hubble catalogue to find photos of his racing KR-40’s. I was sure they were alternating twins with a side exhaust similar to these KR-38 and KR-55’s.


    Attachments:


    squierka39

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 610
    Topics: 34
    #69951
    quote Mumbles:

    I’m trying to find my Hubble catalogue to find photos of his racing KR-40’s. I was sure they were alternating twins with a side exhaust similar to these KR-38 and KR-55’s.

    Nope, the K40 and KR40 where opposed twins, the alternate twin did not get made until 1940 with the K50 and KR55 model.
    I’ve seen a KR40 run on a small period correct hydro. Neat to see them go. Not scorchingly fast, but fun all the same.
    I’m pretty sure Hubble did not make anything for the KR40, it was obsolete by then. Lots of stuff for the KR55 though.


    garry-in-michigan

    Lifetime Member
    Replies: 3583
    Topics: 31
    #69956

    The KR-55 powerhead was used on a water pump used by the Army & Navy services During WW2. Hundreds were available as surplus after the war. If your KR-55 has an alnico magnet magneto, it was a late model Army surplus pump, probably built by Hubble. . . 😎


    spike


    Replies: 37
    Topics: 16
    #69957

    There seems to be some confusion arising between the 1928 opposed KR and the much later alternate 1930’s KR.

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