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Atlas K2F magneto leads

Discussion in 'Other Norton Motorcycles' started by pierodn, Dec 1, 2019.

  1. pierodn


    Nov 10, 2012
    Hi All.
    Please, i have some difficult to understand where they go the Magneto's leads.
    The rear lead (bottom side far from barrells) should go to the left spark plug, and the upper side lead (close to the barrells) should go to the right spark plug.
    Is it correct, wrong, or are they interchangeable?.
    Thank you.
  2. mdt-son


    Jan 19, 2012
    Inside the K2F, there is one set of points (a contact breaker) and effectively a distributor, linking the opening of the contact breaker with the respective side of the distributor. For most british twins, the points open and the distributor connects every 180 degrees (K2F for Vincent V-twins have a different firing pattern). Hence there is one spark per 180 degree mageto revolution. The drive ratio of the K2F is 1:2, hence there is one spark per 360 degree crankshaft revolution. As long as your magneto is timed correctly, either high tension output of your magneto may connect to either spark plug. I suggest you connect the forward HT output to the left cylinder and the rear HT output to the right cylinder, as this will yield approximately equal length chords.

  3. Triton Thrasher

    Triton Thrasher

    Feb 10, 2009
    Usually, bikes with a K2F had the rear pickup connected to the timing (right hand) side of the engine. What does the Norton manual say?

    However, what is necessary for the engine to run is that the HT pickup brush that is touching the slip ring brass segment is connected to the spark plug in the cylinder that is near the top of the compression stroke.

    The engine cannot run on a spark at the end of the exhaust stroke!
  4. texasSlick

    texasSlick VIP MEMBER

    Jan 2, 2013
    It is fully explained here .....


    The magneto can be timed either way as the above two posters allude to.

    The Norton manual says to time the left cylinder with the lower cam ramp, with the rubbing block at the five o'clock position. When done this way, the lower high tension pickup should be directed to the left cylinder. This is the way the procedure in the link above is written.

    If the left cylinder is timed with the rubbing block on the high cam ramp, at the 11 o'clock position, then the upper high tension pickup is directed to the left cylinder.

    I have seen it done both ways and it should not make any difference in performance.

    As mdt-son says, the internals of the K2F is a distributor, which is the function of the slip ring. When the rubbing block is on the lower cam ramp, the slip ring is directing spark to the lower high tension pickup, and vs. versa.

  5. pierodn


    Nov 10, 2012
    Hi and thank you to All.
    With new 0,20 with little domed head pistins (japanise Teokoku pistons and rings) i have setted Magneto to 31 degree BTDC.
    Thank you.

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