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Thread: 45 Magnum Engine

  1. #1

    Default 45 Magnum Engine

    Good 'Day All,

    I purchased a set of 45 cases that have been welded, machined and what I thought was ready to go to build a 45 magnum engine, however the cylinder bolt pattern do not match the early sportster cylinders I have. Below is a picture of the bolt hole pattern the was installed.
    Can anybody tell which bolt pattern I have?
    Disregard the actual gasket pictured as it was only used for illustration purposes, and measurments.
    Cylinder base gasket measurements.jpg

    Any help would be greatly appreciated.

    Thanks Brian

  2. #2


    Doesn't look like 900cc Sportster, the spigot hole is too small (should be 3.25"). The 1000cc is even bigger.
    Is that gasket rotated? The 2 pairs of left case studs are 2-7/8" apart from each other (same as a 45, but father to the left on the new metal).
    Got a picture of the case deck?

  3. #3


    Sorry for the delay, but I was away on holidays. Here are the pictures as per your request.

    For some reason I cant get them to view the right way???Pic1.jpgPic2.jpgPic3.jpgPic4.jpgPic5.jpg

    Also please accept the crudeness of the down & dirty caliper measurments. Hopefully you can make heads or tail of it.

    Last edited by 45-Brian; 09-10-2018 at 08:07 PM.

  4. #4


    Thanks, but doesn't match any Sportster I know of, everything is too small.
    This may be for an English single, for more about this and some pictures of a Magnum under construction see my page here:

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