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1985 25HP Mercury outboard, serial 6594271

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  • 1985 25HP Mercury outboard, serial 6594271

    had intermittent spark, pulled flywheel, magnets unglued and next to each other. went to Yamaha for magnet epoxy and reglued magnets in original spots and believe that polarity is correct. had spark on #2 but not on #1. tested stator, coils & trigger. replaced switch box. have great spark both cylinders. engine starts hard and runs rough. 135-140 compression on both cylinders. both spark plugs new. motor had sat for several years. disassembled carburator and it was spotless.

    #1 question: one magnet was half the size of the other in flywheel. is this correct? the motor is a 25HP electric start.
    #2 question: any ideas on where to go from here?

    I would appreciate any help or suggestions. Thanks, Steve.

  • #2
    Not sure if both magnets are same size or not. Need to check stator output voltage with a peak reading voltmeter to see if within specs, need to check timing on both cylinders to see firing at correct time.
    Regards
    Boats.net
    Mercury Outboard Parts
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    • #3
      Flywheel magnets

      why would timing change when nothing was disturbed except regluing of the magnets? the reason I ask about the magnets is that in all of my boat manuals, when they show the magnets, they are the same size. The magnets that I reglued did not look broken. They were perfectly squared.

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      • #4
        The magnets control the ignition charge.
        Regards
        Boats.net
        Mercury Outboard Parts
        MerCruiser Parts
        Force Outboard Parts
        Mariner Outboard Parts

        Comment

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