Surface ground rings

[wigglesworth]

Isn't a fat ring better than no ring? NAL.......

A thin ring will outperform a thick ring quite handily. But its a trade off, as they will wear a whole lot faster.

I think ill give Hastings a call, which was suggested to my by another member, and see what it would cost to have a couple sets made. I never thought about the cast vs. tool steel issue. I bet a cast ring wouldnt last long as thin as they are.

 

[AUSSIE1]

A square cylinder... Great idear Al

I really do enjoy havin all this knowledge at my fingertips. Heck this morning I was gettin schooled on chainsaws at 5am on my way to work.

Honda played with an oval piston in their race bikes many years ago! :msp_scared:

 

[Jacob J.]

A thin ring will outperform a thick ring quite handily. But its a trade off, as they will wear a whole lot faster.

It depends on what kind of performance characteristics you're looking for. There's a lot less friction with a thin ring so you get more RPM, but a thicker
ring seals better, transfers heat better, and is a lot more durable. There's a reason all the major OEMs switched to 1.2mm rings which are a good blend
of performance, longevity, and durability.

I ran two Jonsereds 930s side by side. One with a new factory thin-ring piston and one with a new Stihl 066 piston. The 066 piston saw by far was way
better to cut logs with. I ended up trading off the thin-ring piston saw.

 

[wigglesworth]

It depends on what kind of performance characteristics you're looking for. There's a lot less friction with a thin ring so you get more RPM, but a thicker
ring seals better, transfers heat better, and is a lot more durable. There's a reason all the major OEMs switched to 1.2mm rings which are a good blend
of performance, longevity, and durability.

I ran two Jonsereds 930s side by side. One with a new factory thin-ring piston and one with a new Stihl 066 piston. The 066 piston saw by far was way
better to cut logs with. I ended up trading off the thin-ring piston saw.

Im looking to make a 5ci cookie cutter, so the thin rings is what im after.

 

[Tzed250]

A square cylinder... Great idear Al

I really do enjoy havin all this knowledge at my fingertips. Heck this morning I was gettin schooled on chainsaws at 5am on my way to work.

Honda played with an oval piston in their race bikes many years ago! :msp_scared:

Yes!! Honda NR500, circa 1979. Essentially a V8 in a class restricted to four cylinders. Your local dealer won't have a set of rings in stock...

 

[Denis Gionet]

My old GPz750 was .040" oversize, and I put .050" rings in it, and ground the ends to the minimum spec (I've also done this on sleds...). That bike had about 180 psi compression (and stage 2 cams), and would easily keep up with the newer liquid cooled bikes my buds had.

Something to keep in mind, if you run out of options. Get rings from something 1 or 2 mm bigger bore, that are the right thickness, and trim to fit. The bore won't last as long with the extra tension from the rings, but they'll be plenty tight in there !

 

[stihl038x2]

Here's a little "light reading" for those who want to "roll their own"


http://modelenginenews.org/techniques/piston_rings.html#1


Steve

 

[promac850]

Yes!! Honda NR500, circa 1979. Essentially a V8 in a class restricted to four cylinders. Your local dealer won't have a set of rings in stock...

Another one is the NR750... from what I've read, these bikes sound beautiful.

 

[Tzed250]

Another one is the NR750... from what I've read, these bikes sound beautiful.

Two of them. The NR750 endurance racer, and the NR750 streetbike. Neither as serious as the NR500. Reportedly the redline on the NR500 was over 22,000 rpm. Remember that is a 125 piston in the picture. The valves were about the size of a golf tee.