Timing on a KG4H Mercury

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  • tbuck19


    Replies: 2
    Topics: 1
    #4813

    Hello AOMCI,
    I just finished cleaning the points on my rebuilt KG4 Merc, i am doing this because I’m not getting a spark. I was wondering if anyone knows what the gaps should be set to on the points, and should they be set at 50% throttle or something else? Any info is greatly appreciated.


    jeff-register

    US Member - 2 Years
    Replies: 1564
    Topics: 54
    #40695

    Hi,
    I can help you some & if you have a better way. . First pull the flywheel & plugs Turn over the motor till the points just open & stop. Push in a screwdriver to find the piston closest to the top. That matches the points that are opened. Turn the motor over till the same points open as large as possable. Set that set at .18 & turn over the motor over a half a turn to the points are open as high as they will go. The next piston should be very close to the top & set it at .18. Try starting the motor.
    P.S. Clean the points too.


    tbuck19


    Replies: 2
    Topics: 1
    #40696

    Thanks Jeff. I will try that and update on the result soon.


    tbuck19


    Replies: 2
    Topics: 1
    #40697

    What should the throttle be set at when doing this?


    fisherman6

    US Member - 2 Years
    Replies: 1702
    Topics: 34
    #40698

    The throttle setting should be irrelevant since the cam is keyed to the crank. All that matters is that the point gap us set when they are at the highest point on the cam. I usually set them at the idle stop or WOT stop just so the mag plate is least likely to move while setting the point gap. One or the other position usually makes access easier.

    That said, I haven’t worked on any old Mercs yet so if it is somehow different I apologize in advance. By the parts diagram it looks pretty close to any other magneto so I’m assuming this is correct. That is how I set my OMC motors though. I know Carl liked things a little different so anything is possible.
    -Ben

    OldJohnnyRude on YouTube


    dave-bernard

    US Member - 1 Year (includes $3 online payment fee)
    Replies: 2014
    Topics: 30
    #40706

    throttle doesn’t matter just set when they are at the highest point on the cam. get close then I use the throttle to fine tune the high point.


    jeff-register

    US Member - 2 Years
    Replies: 1564
    Topics: 54
    #40707

    .Seems I’m really close the wAY it was describebed. Just watch the crank to see when the points open as far as opened, then set the next set of points 180 degrees out from the first. Very important to be 190 degrees out from the first set as the motor runs perfect 180 degrees out from the other. Next comes thw rest of the motor to see if it is correct too. Next comes the CC the chambers & ports, be sure to check reed valves for being straight. Bearings true & a zillion other items to be correct too, not counting ign & carb.


    John Schubert

    Lifetime Member
    Replies: 82
    Topics: 15
    #40741

    Throttle is irrelevant, actuates the carb throttle shaft. Mag advance lever should be set at full advance (all the way to the right). Points set at the highest point of the cam which if I recall matches up with the tab that slides in to the crankshaft flywheel key slot. The key locks the cam down in it’s correct position.

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