4 cyclin ?

Post in 'The Gear' started by brokeburner, Apr 10, 2009.

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  1. brokeburner

    brokeburner
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    What does the term 4 cyclin mean to adjusting your jets im totally lost. thx
     
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  2. kevin j

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    It is a rich mixture until it just starts to stumble or stutter.
    In a typical 4 stroke engine you adjust until it sounds the highest best running rpm. Not the same procedure for two stroke.
    2 cycles run faster and faster as the mixture is leaned out, then start to 'scream' which is almost a runaway sound. That is way lean.
    Lean mixtures burn slower and much hotter, meaning less power but most importantly heating up of piston crown and exhaust area. Eventually the lean condition can cause seizure. Air leaks can also cause lean seizure.

    Richen it up until it just starts to '4 cycle'. if in doubt go rich


    madsens1.com has some audio tracks
     
  3. fyrwoodguy

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    there it is a correct simple answer ;-)
     
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  4. taxidermist

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  5. mobetter

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    Four cycling is more of a burbling sound at the higher RPMs. It will go away once the saw has some load on it. Too lean and you can melt the piston to the cylinder wall. If in doubt always err on the rich side, your saw will thank you. The old racers had a saying; " Lean is mean, but fat is where it's at" Have you ever heard; "They always run best right before they blow up" An engine will run like a banshee lean, but it sure won't last long.
     
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  6. brokeburner

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    ok so richin it up till it starts stumblin stutterin a little my saw was blowin a little smoke at high rpm i leaned it up a little no stumblin no stutterin is that ok. where is some good readin on adjustin 2 cycle carbs
     
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  7. LLigetfa

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    Is that with load or no load? Is that with WOT? Can you hold WOT without it screaming?

    Unless it was under load, I htink you have it too lean. The 4 cycling should hold the revs down on WOT.
     
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  8. taxidermist

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    see above post cant get any better than that reading. If you want to be dead nuts you have to tune it with a tach to the factory RPM.
     
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  9. mobetter

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    You probably have it too lean if you're not burbling at WOT. Try warming up the saw and hold it wide open for no more than a few seconds, it should stutter/burble and smoke a bit. When you put it in some wood it should smooth right out. Check out that Madsens link, it is good stuff. If any doubt, turn the H screw out a little. A spark plug now and then is a lot cheaper than a new cylinder/piston. Some saws have rev limiters so you could still be lean and have a stumble. Return the H screw to where it smokes a little, and burbles at WOT and you should be good.
     
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