PISTON RING OR RINGS?

I don't worry about this stuff. As and engineer i can say that the finishes and tolerances in engines now are so much better than in the 'good old days' that the engines are much better today. truth be told I'm not sure the extra moving mass of the extra ring and extra length in the piston would be worth it even if it didn't cost anything.

The R&D;types earn thier money.

Whith a good brand saw you're only going to see a piston out if it's been run with out oil or run with a lean setting. Two rings will not help that.

ATB,
Mike

I know that was a selling point on my stihl blower. 2 rings vs the standard one. Really, how much additional cost to add another groove and ring?

I don't think there are any hard and fast rules. I've seen everything from none on my model airplane engine to one on a little weed eater, up to 3 compression rings and two oil scrapers an a big 2-stroke diesel engine. All else being equal, I would think more rings would make a higher compression / less blow by / cleaner engine.

The size, design, and number of rings all have certain costs, both mechanical and financial - I would not consider those or almost any other single engine design feature to be a "quality indicator" - such things are all part of a system and all interact with each other in a very complex set of inter-related compromises... I would say it is more important to look at the reputation of the product and / or company to see if they have a reputation for "getting it right" in the overall picture....

Gooserider

My dad told me that the older Stihls have dual rings and that's why they are hard to pull over. But man, it barks when it goes...