Adding a ring?
 

With the impressive results folks are having with the newer twin-ring Ryobi 31cc vs the older single-ring versions, plus the fact that most of the "pro-grade" industrial engines (e.g. Kioritz, Echo, Zenoah, etc.) all have dual ring pistons, wouldn't it be a fairly simple hop-up to machine an extra groove on a single-ring piston to accept a second ring? Afterall, larger automotive engines typically have several rings - some for compression and some for oil control.

It shouldn't be all that difficult if you have access to a lathe, should it? Has anybody tried this?

Adding a ring?
 

Some pistons have a little extra meat where the ring or rings are and as you move down the skirt it gets thin pretty fast. On the Ryobi I dont know, If there is enough material there it should be a pretty straight forward modification. A fixture or something to hold the piston might need to be made up to keep from crushing or scaring the piston in the chuck of a lathe.

Adam

Adding a ring?
 

I thought about doing this on an old single-ring small Ryobi (26 cc -- not the 31) and decided there just wasn't enough space above the wrist pin hole to squeeze one in. On other engines this might be doable. I too would be interested to hear if anyone has done it...

Adding a ring?
 

Why couldn't you just order a new 2-ring piston and stuff it in the old engine? Unless the pin diameter, bore, stroke, shape, and weight are different, it should work.

Doug

Adding a ring?
 

It's going to take more than an extra ring to get the power of the old motors up to that of the new one. The new cylinder has a larger more "D" shaped exhaust port that is unbridged. The best that I can remember, the transfers ports are a little different too, but don't quote me on that, it's been a little while since I've had them apart to compare. I really can't see why the guys want to buy the old refurbished motors from Harbor Freight when you can get a new twin ring from Wal-Mart for around $69. There is a big difference in power between the old one and the new one.

Adding a ring?
 

Actually, I really had Poulan chainsaws in mind. With Ryobi twin ring refurbs going for $49 a pop, it really doesn't make much sense working on the old ones. The bigger Poulans (46cc, 50cc, 54cc, etc.) are still all single-ring and might just benefit from a second ring.

Adding a ring?
 

Volfy, maybe you can find a dual ring piston from a different engine/make that fits or can be made to fit? you might also find something with a taller crown to allow a compression increase. talk to some long-time saw shop guys, if it's a possibility they would be the ones to know.

dave