dual ring pistons vs single ring piston

[jokers]

I`m not sure I`m following Marty`s logic on the blow by issue, is it being suggested that there could be enough fuel transferred to the crankcase by blowby on the compression stroke, to cause an upward, 180° out of time, powerstroke? If there were no physical deficiency such as a missing piston skirt or grossly mispositioned transfer port, you could not get enough blow by in an engine with normal ring seal, or it would lack the compression and expansion needed to make power, right? As far as power delivery to the chain is concerned, it doesn`t matter which direction the piston is pushed, power is delivered from the rotating mass of the crank in a continuous motion. All that gibberish being stated, let me say that I had one of the early 371xps with a single ring, ran the tail off it and it still had excellent compression. I sold it to a professional logger, via ebay, who not only sent me a very nice email, but put it in my feedback that they love the saw. My point being that I`m sure one ring vs two has to have some effect on longevity, but with proper maintenance it is minimal. BTW, power on that saw was excellent. I`m thinking that in the every day world, the power difference between a one ring saw and a two ring saw is irrelevant. Russ

 

[chainsawworld]

i am not sure of the question but the fly wheel carries the power over while the engine is not in the power stroke, not combustion in the crank. mix is present in the crank for that is what lubes the internal parts. as far as 1 or 2 ring pistons, i use and compete with both and both seem to be just fine. perhaps i got off the subject a bit. marty

 

[DaveCA]

"...but with proper maintenance...in the every day world..." Who's everyday world?
Call me a cynic, I'm thinkin the two ring piston will suffer abuse more gracefully on average when looking the great number of saws sold.

 

[Dieseldog]

Just my two cents for anyone that knows about diesels and the two ring Caterpillar 3208 throw away midsize diesel engine. Built with only a compression and a oil ring it smoked excessive and wore out fast. Recently while deciding on a professional saw in the 57cc class it was my experience with these diesels that made me appreciate the reasoning behind having two compression rings vs one! It helped me finally decide on and purchase a new Stihl MS340. Later Dieseldog!

 

[stihltech]

rings

I very seldom replace any worn out rings on a Stihl saw. We had single rings on 041FB, but still had very few ever worn out. Stihl used a thicker ring than Husky at that time, I do not know how thick a Husky ring is now.
Husky used a "racing ring"on some of the saws I worked on (and sold). This was 10 to 15 years ago. We said the Stihl ring was wearing in when the Husky ring was wearing out. They did break in very fast , though. I have a box of rings for all Stihl saws that is just collecting dust now.

 

[jokers]

DaveCA, just what is your point, taking what essentially became two abstract sections of my comment and then quoting them as if from one sentence? Let me guess, reading comprehension isn`t your forte'. A profitable business person, or an employee who isn`t ethically challenged always takes time to do proper required maintenance, realizing that protecting the investment protects your bottom line, whether you are the employer or employee. Struggling all day with a beat up POS piece of equipment to make half of your projected quota is not the hallmark of intelligence.

Stihltech, suggesting for the sake of argument that ebay auctions represent a fair cross section of what people in North America are using, fixing, and selling, why is it that 9 out of 10 saws either with a new top end or needing one, are Stihl? Not saying that this can always be attributed to ring quality or number, but broke is Stihl broke isn`t it? Russ

 

[don]

Stihl saws and multi rings

Jokers for anyone to answer your statement as to why more Stihls are on ebay requires variables not easily available. How many chainsaws are there ? What is the life expectancy or design life? How many people who owns a saw would sell them , especially on the internet? Assumptions could easily be the sellers on eBay are not a good sample to determine what North America uses for chainsaws. I think there is much more to ring technology than we can elaborate here on this site. Some design, cost and production engineering went into these designs and unless we get those specs we just won't know why each manufacturer went for single or multi pistons. Has anyone here flat out asked the saw manufacturers what market share they have? Has anyone asked them the design criteria between single or multi pistons for their engines? Do we have any company reps out there?

 

[John in MA]

Nationwide, there are more Stihls sold than any other pro saw. Everything being equal, you'd end up with more blown Stihls because of that. They are more expensive than any other saw I've seen. Also, the name recognition makes for more idiot-homeowner types buying and abusing them.

So, you get a lots of saws, many damaged from neglect, and worth a lot of money. That equals lots on eBay.

"Hey dude, look at that saw in the dumpser. It says Stihl! We can sell it on eBay!" I think that happned to my 028.

 

[stihltech]

rings

Let's face it, there re lot of people out there that don't know where the air filter is on a chain saw. Ask any shop operator about the misuse of chainsaws. You pull the filter cover and dump out the sawdust to find it so you can clean it.
I do not know the figures, but I think Stihl is the #1 seller, at least in my area. The dealer base has something to do with this (OK the GOOD ones).

 

[jokers]

Hey Don, you didn`t read my statement correctly.

John in MA, you`re sort of right, but Stihl sells more saws worldwide than any other brand, not necesssarily Pro saws. it looks like their stronghold on the Pro market has slipped.

Stihltech, yeah I agree with you that many people just don`t care to take care of their equipment and that leads to many failures. It`s my opinion that they, Stihl, are creating a legacy for themselves with all that hoo haw about how indestructable they are, and then by selling all that consumer grade stuff under the premise that it is as good as their best. Not really seeking an argument but I am offering a counterpoint to your statement that the Stihls were just wearing in when the when the Huskies were wearing out. There are too many people out there who take an unchallenged statement for fact. Russ

 

[jokers]

Don, almost forgot to mention, company reps are more for marketing and damage control. I wouldn`t seek out their opinions on much of anything, including whether or not a sunny sky is generally blue. LOL Russ

 

[chainsawworld]

i have to dis-agree with the statement stihls are just breaking in when husky is breaking down. you sound like me when i thought the only real saw is stihl. in my tests i have found great,good,poor and junk in many differant saw brands. this includes stihl, all the eletrolux,makita,solo,echo,shindawa and so on. some may run outstanding but get poor rating due to the endurance of some of the parts(ie. solo has had trouble with throttle linkage in the smaller saws).
i used to run the 044 stihl all day every day. one day i was working in huricane flloyd in the pouring rain and the 044 would not start, at all. this is the only problem i had with that saw. i also ran it in stock saw competitions and it was a winner. now i run the 372xp husky every day. it started in the rain and ran the rest of the day. it goes to competitions and wins over the 044's.
not only is care of the saw a major factor in saw life but picking the right saw for the job is too. you can't buy a 017 stihl (1.84 cubic inches) and expect to work as a professional logger every day. i have seen a great deal of saw abuse most of which comes from lack of knowledge. others just don't care.
i do not prasie nor condemn any saw unless i have run it. to say one brand is better then others without proof or because i sell them is poor business. marty

 

[jokers]

Very well put Marty, and I know, and it`s easy to verify that you are a man who speaks from experience. Russ

 

[WRW]

Marty's story reminds me of a cousin that beat a Corvette with his Olds 442. The other driver was baffled. To make a point, my cousin swapped cars with him and beat him with the Corvette that same night. A lot has to do with how good an operator you are.

 

[DaveCA]

Russ, you said: " just what is your point...Let me guess, reading comprehension isn`t your forte'"
Russ, I mean to do no harm to you. If you don't get the point, reread my post, then if you still don't get it, ask again if you like.
I found this poet from a man who drops in here sometimes. Perhaps you will enjoy it, or not. The choice is yours.

The Idealist
by Robert W. Service

Oh you who have daring deeds to tell!
And you who have felt Ambition's spell!
Have you heard of the louse who longed to dwell
In the golden hair of a queen?
He sighed all day and he sighed all night,
And no one could understand it quite,
For the head of a slut is a louse's delight,
But he pined for the head of a queen.

So he left his kinsfolk in merry play,
And off by his lonesome he stole away,
From the home of his youth so bright and gay,
And gloriously unclean.
And at last he came to the palace gate,
And he made his way in a manner straight
(For a louse may go where a man must wait)
To the tiring-room of the queen.

The queen she spake to her tiring-maid:
"There's something the matter, I'm afraid.
To-night ere for sleep my hair ye braid,
Just see what may be seen."
And lo, when they combed that shining hair
They found him alone in his glory there,
And he cried: "I die, but I do not care,
For I've lived in the head of a queen!"

 

[stihltech]

rings

Now read my post again. I did not say the saw wore out, I said the ring wore out. And I have replaced a few Husky rings in that era saw.

 

[Fish]

Dang, I missed a good fight, I think.
In most cases, two cycles are not retired because the ring{s}
are worn out, but because of catastrophic lean seizures or
other parts that are broken or worn out, and the cost of repair
exceeds the value of the unit. Whether 1 or 2 rings is fairly
irrelevant, as a burnt up/melted piston is just that on either
unit, and 1 or 2 rings is not the cause of the failure. Brand
bashing is unneeded as all the manufacturers are putting out
some junk, some maybe more than others.

 

[jokers]

Alright Stihltech, I took the liberty, or should I say laziness of implying saw when I should have specifically said ring. My bad. You`re still beating your chest and blowing smoke where the sun don`t shine in my opinion.

DaveCA, I reread your post and it is still taking parts of two statements about two different attributes and trying to make one statement out of the whole mess. First I spoke about longevity of single ring saws and stated although I think the net effect of one ring on longevity is minimal if maintained properly, I implied, I thought rather clearly, that two would last longer. So how do you miscontrue that statement to have anything to do with my next statement regarding relative power outputs between two ring and one ring saws in the everyday world, that would be anyone who is not using a highly modified saw for a special application. Two different observations being noted by me. Your last statement doesn`t make sense after "on average" without adding words. Sorry if my response to you rubbed you the wrong way, but it sure looked like you were trying to kick me around a little. I stand by my statements whether they strike you as idealistic or not. BTW, I appreciate your taking the time to post Service, he is one of the best. Russ

 

[Dagger]

2 rings?....Nope....its not for better compression, its not for cleaning the oil from the cyl, not in a 2 stroke.
No..its not for longer life...heat transfer?,hardly..an modern 2 cycle saw is 80%cooled by the fuel..not the air. I love you guys..and I really liked Chainsaworlds post..very good sence with no blind brand loyalty. A true wrench at heart he is I think.
but where some of these other ideas come from????

A second ring is simply a function of piston stabilazition in 99% of the designs in tha last 20 years or so. When we achieved the ability to hold manufacturing tolerences to a much closer degree we found we could do away with the second ring because it simply was not needed in a 2 cycle design. And remember that many pistons are not manugfactured in the same plant as the jug...many not even the same country! The second ring you find in todays saws is only found where for whatever reason manufacturung tolerence is large, and at the high rpms of todays equipment piston slap will become a problem. Consider the saws you are talking about with 2 rings today..low end consumer stuff, or short life designs made to a price point spec. Break down a new one. you will most likely find 5 to 6 tho of skirt clearance,or more on a new saw and a short skirt to boot because of the porting necessory to get the rpms. now check a single ring design of high quality...some no doubt cant even discern the clearance spec...but 002 to 003 is what you will find!

In truth for those of you who want to judge the quality of a design by how many rings it has..the reality is the lesser quality designs most likely are the ones with 2 rings!
There are exceptions..but it has to due with cylinder diameter and shirt length and rpm level...and weather the piston need the stabilizing effect of a second ring.

 

[bwalker]

A second ring is simply a function of piston stabilazition

What do you mean by this. Temperature stabilization? Tolerance stabilization.