Power head assembly

[genetoo]

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]

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]

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.

[The Boat House]

• This reply was modified 3 years, 5 months ago by The Boat House.
• This reply was modified 3 years, 5 months ago by The Boat House.

1 user thanked author for this post.

cajuncook1

[cajuncook1]

[genetoo]

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

[cajuncook1]

PM (private message) your email address.

Cajuncook1

[cajuncook1]

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

Cajun

[Author]

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