Reply To: Weak spark on 1973 20 Hp Johnson

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July 24, 2020 at 1:02 am #209673
Phil Budne
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    The 25hp 22ci engines had a number of changes other than the carb. I seem to recall they include (at least):

    Balanced crank
    Piston pin location changed (for porting and/or compression)
    Different cylinder head
    Exhaust tuning

    And maybe also improvements in the lower unit (gear case)

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