One ring vs two

[jmssaws]

Did stihl change there rings at some point in the 066/660's? Seems I've noticed two different styles.

 

[Deets066]

Did stihl change there rings at some point in the 066/660's? Seems I've noticed two different styles.

What differences? 54mm x 1.2 as far as I know

 

[jmssaws]

Not the thickness just the style,they just look different than they use to. More of a bevel perhaps?

 

[Deets066]

Switched manufacturers maybe

 

[Jughead]

ho lee chit!.......geeks!


wait a minute!wonder how much residual oil the bottom ring land will hold only using one ring.....vs only running one ring in the bottom land.running the ring in the bottom land would create a space for residual oil for top end lube there fore creating less friction But uh... i got a headache.

 

[jacob j.]

Nope,wrong analogy. More wheels,more rolling resistance. And pulls through the curve harder.Trust me.

Why would a manufacturer opt to use two thin (or thinner) rings as opposed to one thick ring?

 

[jmssaws]

Why would a manufacturer opt to use two thin (or thinner) rings as opposed to one thick ring?

It sold a bunch of saws.

 

[exSW]

Why would a manufacturer opt to use two thin (or thinner) rings as opposed to one thick ring?

In automotive applications some rings are " wiper" rings . As far as saws,ask a design engineer.

 

[Adirondackstihl]

Why would a manufacturer opt to use two thin (or thinner) rings as opposed to one thick ring?

Less friction
Less reciprocating mass

????

 

[Mastermind]

Stihl For Workin........Husky For Racin

 

[bwalker]

I messed with running single ring Wiseco pistons in dirt bikes vs the stock double ring pistons. I didn't notice any differance in performance. They also seemed to lose compression a bit faster.
With that said I have totaly abused single ring Husky's and never had one loose compression.

 

[Hedgerow]

Stihl For Workin........Husky For Racin

Dolmars for just sheer awesomeness...

 

[tree monkey]

aint questioning you, but why?

the open ring grove is a free port from the transfer port to the exhaust port. this happens before the transfer port opens.

postage is gonna eat me alive if'n I gotta send nine more


c'mon Dave ya fat *f-word, maybe multi quote now and then, you don't even want a new husky, geeesh

number 11 will be even better

wouldn't an empty groove carry a bit more oil and weigh less than filling with something?
maybe my brain istoo tired to get it, I will re-read after a nap

yes, but is it worth the trade off?

The opening of the transfers are not as big when you don't have to raise them a mile.

port area is the same. the piston covers part of the port at bdc

If you start out closer to your desired transfer degree, the final transfer opening won't be as tall. Smaller opening= better transfer velocity

read above, think about it more, your close

 

[jacob j.]

In automotive applications some rings are " wiper" rings . As far as saws,ask a design engineer.

The point I was making is that there are trade-offs with each design. Thicker rings give better sealing at the trade off of higher friction (referring your 'rolling resistance' analogy). Thin rings give less resistance but higher overall RPM with quicker spool-up and poorer sealing. One ring gives less resistance but less overall durability. It all comes down to the performance characteristics that are desired.

Less friction
Less reciprocating mass

????

Yep. Early saws (long before the establishment of the EPA) had two, three, or four thick rings with heavy cranks and flywheels. Stihl started experimenting in the late 60's with one thin ring and one thick ring, or two thick rings spaced a long way apart. IEL had a thick ring just below the crown of the piston and a thick ring on the bottom of the skirt (supposedly for stability). Husqvarna experimented with three and even four .024" thin rings (the 394 prototypes came with triple thin ring pistons). McCulloch and Homelite developed their own 'Dykes' ring designs with one L-shaped ring right on the edge of the crown.

As saws evolved, crankshafts, flywheels, connecting rods, and pistons got lighter. Chain and bars were reduced in mass. Clutches and drums got thinner and lighter. Materials and manufacturing methods have improved. Now you have equivalent displacement saws that weigh a fraction of what the same displacement saw did 30-40 years ago. So now, different performance characteristics are desirable.

 

[tree monkey]

Stihl For Workin........Husky For Racin

hay there buster, that's not your line, came from cahoon

 

[Deets066]

the open ring grove is a free port from the transfer port to the exhaust port. this happens before the transfer port opens.



number 11 will be even better



yes, but is it worth the trade off?



port area is the same. the piston covers part of the port at bdc


read above, think about it more, your close

If the area is the same at BDC you would still pick up velocity if the uppers are smaller. Not because of area of port, but it would be less case volume if they were ground on less?

 

[tree monkey]

yep. you get a cookie

 

[Deets066]

If the area is the same at BDC you would still pick up velocity if the uppers are smaller. Not because of area of port, but it would be less case volume if they were ground on less?

So a guy could possibly epoxy up the bottoms of the upper trans to just below the piston crown at BDC and maybe pick up a little?

 

[Deets066]

yep. you get a cookie

I like cookies, pink ones

 

[Deets066]

So a guy could possibly epoxy up the bottoms of the upper trans to just below the piston crown at BDC and maybe pick up a little?

It might be more work than it's worth after thinkin about it.... I'd have to look at a jug to see if it would even be feasible.