Power head assembly

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  • genetoo

    US Member - 1 Year
    Replies: 5
    Topics: 6
    #221064

    A nice member talked me into rebuilding my power head myself so that,s what I,m doing. I already have some questions.

    As far as fitting rings there is what they call measuring the( ring gap )before application of the new rings. process requires one to slip the ring by itself in the cyl bore about 1 inch and measures the ring gap with a mike. My question .Is there a set measurement /tolerance for the ring gap for a outboard?

    I had a old Cushman motorscooter years ago that was rebuilt ,ring gap was never checked and when it got hot it would start to seize up.

    Motor in question is a Johnson TN 28 5 hp

    Gene


    frankr

    US Member - 1 Year
    Replies: 5706
    Topics: 49
    #221069

    Actually, measured with feeler gauges. Specs vary, but I believe it is 0.005″ min 0.015″ max. on the 5hp. Greatest cylinder wear generally is in the ports area. There is more to be concerned about than just ring gap. Side clearance in the rings, piston skirt clearance, etc.

    My restored Cushman would start to seize at high speeds also. I finally figured out it was because I made it pretty with a nice coat of black paint on the cast iron cylinder fins.


    Mumbles

    Canada Member - 2 Years
    Replies: 4930
    Topics: 268
    #221070

    End gap should be measured at several different spots in a used cylinder to allow for wear and the end gap set at the tightest spot.

    TD-TN-Rings


    The Boat House


    Replies: 3402
    Topics: 85
    #221130

    You're only as smart as the person you're talking to.

    1 user thanked author for this post.

    cajuncook1

    US Member - 1 Year
    Replies: 823
    Topics: 70
    #221237

    Johnson-TN-specifications

    Attachments:

    genetoo

    US Member - 1 Year
    Replies: 5
    Topics: 6
    #221292

    YOU GUYS ARE THE BEST !!!!! Gene in Farmington, Mn


    cajuncook1

    US Member - 1 Year
    Replies: 823
    Topics: 70
    #221294

    PM (private message) your email address.

    Cajuncook1


    cajuncook1

    US Member - 1 Year
    Replies: 823
    Topics: 70
    #221395

    Gene, were you able to receive the email I sent and the download link?

    Cajun

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