Piston rings for a Johnson SR-45

[hirschlt37]

I ordered standard piston rings for my SR-45, received them but they are to thick. When placed in the groove of the piston the can’t fully collapse…result the cylinder won’t fit over the piston/ring assembly. Is this a common problem with these old motors? Checked my Lockwood-Ash…same issue…standard rings are to thick. Did I miss something in the process? Where do you go to by special rings?? Thanks, Gary in Michigan

[RICHARD A. WHITE]

One question, did you meticulously clean the ring grooves?

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[pm-t2]

replacement rings for old motors often have to be machined on the ID of the ring to make them thinner.

Most rings sold have a radial thickness of 0.110", give or take, but many motors need a radial thickness of 3/32" (0.093") or just slightly under. Some I’ve worked on required rings with a radial thickness of only around 0.080".

Very simple way to verify if your ring is correct or not. Measure the depth of your ring groove(s). Measure the radial thickness of the ring. Thickness obviously has to be less than the depth to work.

Hope this helps.

Best,
PM T2

[hirschlt37]

Thanks for the help…yes I did clean the ring grooves out..no dirt/deposits. Luckily a fellow member came up with some 1/16" rings that were thinner….I’ll need to use two to replace a 1/8" ring. Not that I know the problem I’ll approach things differently…don’t recall having an issue with my old Johnson A?

[Author]

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