Are 2 stroke OB piston rings interchangeable w/other devices?

[CN Spots]

If the bore dia. and ring height are the same, could rings from another type of 2 stroke engine be used in place of the rings in a 2 stroke outboard motor?

 

[Dhadley]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

The ring material has to be right for the application. Ring shape has to match the groove in the piston. The ring groove to ring clearance has to match (different ring material expands differently). The ring end gap has to match the use (combustion temp) and so on.

 

[CN Spots]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

Ugh. I was afraid that it was more complex than I'd hoped.

Guess I'll take out a second mortgage on my house and get the Mercury rings.

Thanks Dhadley.

 

[Silvertip]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

Some two strokes have a Dykes or pinned style ring end gap which prevents the ring from rotating and the ends getting snagged on a port. You need rings for your motor for all the reasons indicated above.

 

[Frank Acampora]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

Really, you should go to the forum for your engine--Mercury, I assume by your post. You should state your problem there and ask for help. Do NOT assume the engine needs rings. Outboards typically get little running time compared to other engines and worn rings are not a common problem.

 

[CN Spots]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

Really, you should go to the forum for your engine--Mercury, I assume by your post. You should state your problem there and ask for help. Do NOT assume the engine needs rings. Outboards typically get little running time compared to other engines and worn rings are not a common problem.

The question was related to all two strokes as I've got multiple makes laying all over the place. A substitute ring would come in handy for some of the older, obsolete makes like Elgins. I'm also bummed that a set of OB rings for two tiny 2" pistons cost more than a full set of V8 rings for a small block Chevy. Oh well.

This one in particular had a ring that fell out in two pieces when I removed the piston so it was obviously toast. That cyl had low compression and you could see through the ports that the ring was black as compared to other three that were worn silver. Believe me, I don't go looking for ring jobs.

 

[Silvertip]

Re: Are 2 stroke OB piston rings interchangeable w/other devices?

Marine engine parts, especially outboards, are expensive because of the quantities in which they are built. Millions of small block Chevys have been built over the years which creates a great aftermarket for these parts. Outboard engines are made in much smaller quantities so parts costs are very much higher.