broken ring

Discussion in '2-Stroke Engines' started by cigron, Apr 28, 2010.

  1. cigron

    cigron Member

    Would any one no what would happen if I would use only one ring.I broke one. this has been the most
    unreliable motors I haver had.It`s A 66cc motor
    I put more money and time in it then it`s worth
    I was woundering what would happen if I
    would use only ring

  2. Al.Fisherman

    Al.Fisherman Active Member

    Most likely it would smoke. The top ring is a compression ring and the bottom usually a scraper, meaning the oil is kept out of the combustion chamber and scraped toward the crankcase. Since these engines/piston is so easy to get to...try it and let us know.
  3. wildemere

    wildemere Member

    Both rings are compression rings on these 2 strokes.

    Oil control rings are rarely seen on small 2 strokes, Its a 4 stroke thing.

    Racing 2 strokes and some glow engines run one ring for less friction/more power at the expence of ring life and compression. Its done like that at the design stage though.

    It will go, with less compression and ring life but possibly faster for a while...
  4. G-Superior

    G-Superior Member

    i have a weedeater/strimmer (what ever is called) that runs with no rings with a good compresion and still has exelente power(better than what it was:grin5:) but it is a really expensive brand and all the parts on it are very tight fit which a chinese 2 stroke may not be and the quality of the material are not anywhere as good:whistling: (its a robin subaru made in japan:rolleyes7:)
    i would try running with one ring, it will not kill or seize you engine at all so nothing to worry about and when the compression stats to get lower get a new set(they only come in pairs so you cant but just one)
    Good Luck
  5. cigron

    cigron Member

    Well I took my one ring 66cc two stroke for A ride.
    It ran good for about three miles it went up hill as good as ever
    did. then it lost compression. I was to p#$% to check it out.
    When I cool off ill tear it apart.
  6. motorpsycho

    motorpsycho Active Member

    you have to have 2 rings for a few reasons.
    1. the rings have gaps in them, and the gaps need to be staggered for the cylinder to hold compression. if there is only one ring, there is nothing below it to hold the compression that is seeping past the gap. plus, any unburned fuel will end up in the crank case, Gasoline is not a good lubricant, it will wash the oil off of the bearings.
    2. two rings help keep the piston centered in the cylinder. with only one ring, the bottom of the piston will want to shift sideways every time it goes up & down, which will result in the piston contacting the cylinder wall and causing damage. the piston itself NEVER contacts the cylinder walls, only the rings do.
  7. Vistaman73

    Vistaman73 Member

    I really hope someone can help me, I need a set of 48cc piston rings for a slant zoom 49cc engine. I broke one and i need to replace both. If someone could help me locate a pair and tell me how to put them on without ruining them i would be very happy. thanks a bunch.
  8. AussieSteve

    AussieSteve Active Member

    cigron, there's nothing to gain by only using one ring, but plenty to lose. (Power.)
    Rings aren't expensive. (Did the ring break 'in service' or while disassembling/assembling?)

    motorpsycho, what you said isn't quite true. The rings are only at the top of the piston. The bottom, (skirt), contacts the cylinder wall. (Check out the scuff marks on an old piston.)

    Rings are available in the US from, here, (Piston + Rings $11, 48cc or 66cc),
    or in Oz from ZBox, here, ($7 for 48cc and $9 for 66cc rings).

    To fit them, Vistaman73, use your thumbnails to carefully expand the ring until it just slides over the piston. Ensure that the locator pin in the piston groove is aligned with the ring's end-gap.
    When sliding the barrel on, ensure that the gap stays aligned with the pin and compress the ring onto the piston with your fingers while lowering the barrel.
  9. GearNut

    GearNut Active Member

    Everything you stated is 99% true for a 4-stroke engine and alot of it certainly applies to a 2-stroke as well; However since a 2-stroke's lubrication comes from the pre-mix oil blended into the gas, any unburned fuel that gets past the ring(s) will do no harm to it other that reduce the compression and pumping efficency. It certainly will not wash off any lubricant from the bearings as it is in fact the bearing lubricant.
    Last edited: Jul 9, 2010