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Single vs. Double Piston Rings

Discussion in 'Chainsaw' started by morgaj1, May 18, 2010.

  1. morgaj1

    morgaj1 ArboristSite Operative

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    I have decided to try and replace my seized Husqvarna 353. I have been looking at Stihl, Husqvarna, Dolmar and Echo. The Husqvarna and Dolmar have single piston ring setups and the Stihl and Echo have double piston ring setups. I have bought a lot of weedeaters, blowers, etc and always look for double piston rings. What's the deal with Husky and Dolmar not using them? Would you expect to get less life out of them as compared to the Stihl or Echo?
     
  2. Jacob J.

    Jacob J. Tree Freak

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    Pistons have rings? I thought only Saturn had rings...
     
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  3. Evan

    Evan Addicted to ArboristSite

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    2 rings means twice as much profit for ring makers.

    i have had 044 that i installed with one ring and it was 2 ring piston i saw no ill affects i also replaced and two ring husky piston with a single ring metoer with no ill affects.

    id say maybe the single ring piston will be ragged out 50hrs sooner then the two ring piston
     
  4. spudulike

    spudulike AboristSite Guru

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    Single ring = less friction = faster revving & more power - downside is that you will lose more compression through wear or imperfections as you only have a single ring to seal the bore.

    Double ring will seal better but will cause more friction, slower pickup and less power but you could say the better seal will compensate for this.

    If a single ring piston breaks a ring, the saw stops = less damage, on a double ring, a broken ring can go unnoticed and damege the bore.

    Both work, both have been tested over years of production - go cut some wood:)

    Spud
     
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  5. motor head

    motor head ArboristSite Lurker

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    IMO double ring piston has more grunt in the wood,Try a 372 x torq, 50 mm double ring piston,never saw a single ring 50 mm piston that could perform like that!
     
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  6. blsnelling

    blsnelling Site Sponsor

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    The only the second ring does is add friction. I usually leave the second ring out. The saw will often make several hundred more RPMs in the cut.
     
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  7. 7sleeper

    7sleeper Addicted to ArboristSite

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    Sorry don't agree. At 13000 rpm damage is guarenteed what ever breaks.

    7
     
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  8. CTYank

    CTYank Peripatetic Sawyer

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    With a stock saw, I hope you'll never see revs up that high, considering that 10k seems to be the highest for peak power. Unless one likes to hold the throttle WO for a bit before entering cut. (Like some on YT vids.)
     
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  9. Mastermind

    Mastermind Work Saw Specialist

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    I'm staying out of this. :laugh:
     
  10. edisto

    edisto Spelling/Reality Check

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    It also transfers more heat from the piston, which can mean more fuel in the cylinder.
     
  11. 67L36Driver

    67L36Driver Addicted to ArboristSite

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    Two rings are better than one. I have a Homelite 2000 that blew out the top ring land but, because it had a second ring, it kept running. Ran a very long time judging from the carbon build up on the bottom side ot the top ring.

    Make your single ring Husky, J-Red do that...........................................
     
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  12. 67L36Driver

    67L36Driver Addicted to ArboristSite

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    Two rings are better than one. I have a Homelite 2000 that blew out the top ring land but kept running/cutting because the second ring held compression. Ran a long time judging from the carbon build up on the bottom side of the top ring.

    Do that with your single ring Hoooskeyvarna, J-Red ad nausium.........................

    Homelite piston 002.JPG
     
  13. motor head

    motor head ArboristSite Lurker

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    I have a 625 J red that i put an older model j red double ring piston in,not the thin ring,This saw has just as much power as my 266xp and it has a brand new piston and ring in it,Actually I think the 625 has more grunt.
     
  14. motor head

    motor head ArboristSite Lurker

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    The 625 has a 48mm piston and the 266 has a 50mm piston,Wish i could get a 50mm double ring piston for my 266.
     
  15. zogger

    zogger Tree Freak

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    I have wondered about this. I know single ring has less friction, but I wonder how much more stable and centered the piston stays with two rings. If that matters long term.
     
  16. Franny K

    Franny K xyz

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    What I have been lead to believe is that a single ring will get more cooling effect from it's journey towards the bottom of the stroke than if there was another ring below it. Maybe it is a choice cooler ring use one more heat transfer away from the piston two rings. The balance idea of two staggered ring ends is interesting. A ring of course needs a port free path for the ends which means two such lands for two ring pistons.
     
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  17. motor head

    motor head ArboristSite Lurker

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    Double ring piston with a window:clap:
     
  18. old guy

    old guy ArboristSite Operative

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    This thread sucks, cus I'm waiting for a new meteor piston for an ms360, should I pull one ring? if so which one top or bottem? what to do what to do.:laugh:
    OK, I'm pretty sure must use the top ring.
    John
     
  19. 7sleeper

    7sleeper Addicted to ArboristSite

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    This question has more to do how much man you are! Can your piston take two rings or only one..... ;)

    7
     
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  20. Chris-PA

    Chris-PA Where the Wild Things Are

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    Two rings - one in the belly button and one.......
     

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