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  1. #1
    Seaman Apprentice
    Join Date
    May 2005
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    Hillsboro, Oregon
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    37

    Default 1990 Johnson 70 hp compression?

    My friend has a 1990 Johnson 70 HP motor with three cylinders. They tested out at 115, 115, 116. I know they are close and that's good. I just want to make sure they are high enough.Anybody know if that sounds right?Thanks,ML

  2. #2
    Petty Officer 2nd Class
    Join Date
    Jun 2005
    Location
    Denmark
    Posts
    108

    Default Re: 1990 Johnson 70 hp compression?

    Hey MLYour friends Johnson, is in good condition, according to the comp.test.If lower than 100 PSI, then the motor needs to be overhauled, and also if there is a diff. more than 10% in comp. pressure from one cyl. to another.

  3. #3
    Petty Officer 2nd Class
    Join Date
    Dec 2003
    Location
    Ral NC
    Posts
    184

    Default Re: 1990 Johnson 70 hp compression?

    My 1991 70 has 115 on all 3

  4. #4
    Seaman Apprentice
    Join Date
    May 2005
    Location
    Hillsboro, Oregon
    Posts
    37

    Default Re: 1990 Johnson 70 hp compression?

    On a side note. If an outboard motor has high enough numbers but they are staggered is that ok? As long as the bottom number is within 10% of the top? Why would they be staggered rather than close?Thanks

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