The gremlins have pretty well been resolved from what I have heard , for the average Joe , pretty well full proof assurance that your saw will perform as expected within any environment !
Two-Stroke Oils: All the Same?
- Thread starter Paul Bunions
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Or a couple hundred feet of elevation !
I have never required an actual jetting replacement , usually only a little fattening of the tune . Although on one year of Echo saw in the early part of this millinium , replacement jets were required since they were so lean from the factory . I can't recall geographically were the dude was from lol. To many moons ago , he finally gave up the ghost & brought it to the dealer .
And you should be retuning daily anyways..
Stihl 260 with the fixed jet carb was the same way.
Amen , & how many times in your life time have you seen that Ben . I bet you only need one hand to account for that brother !
Yep that's right
I meant adjustment.
dave ensign
Trapshooter
On my first shot I hit 3 feet in front of the rabbit, on my second shot I hit 3 feet behind the rabbit. On average I eat rabbit. I'd rather run a little rich and send out for dinner.
I wasn't sure bud , but thought I would just mention the issue with fixed jet Echo's example in the early part of 2000 . They were already lean to the point of no return for a richer ratio . Then you go to an even leaner condition with more oil & not a pretty situation , that tuning could not resolve . Only a jet change out would cure . EPA restricted or compliant carbs burnt up many saws back in the early model years as did unknowledgible operators !
This would be correct if the oil was inert and not combusted, but the "Project Farm" video shows that some oils are at least partially combusted.
Straight octane has the formula of C8H10, for the sake of discussion let's say that the oil is C16H18. The densities of the two are approximately the same, but it would take twice as much oxygen to fully combust the C16H18 molecule as compared to a molecule of C8H10. If say the C16H18 was only 50% combusted, the effective O/F ratio would be the same as 100% combustion of C8H10.
Id rather drill all of them, but that's me and because I can.
All oils are combusted. To what degree, where and to what extent depends on load, tuning, oil formulation, etc.
You also have to consider that the only thing your carb tuning accounts for is how much vapor and air are present in the combustion chamber prior to the spark plug firing. Anything liquid detracts from the combustion event by absorbing heat to change its phase to a gas so it can combust. Two cycle oil, specifically is found coating parts such as the piston dome, cylinder walls etc. As such its flashed by the combustion event itself well after the plug fires. As such, and I am speaking in very general terms, it detracts from the amount of heat/power that drives the piston down. However, it does seal the rings better, which adds HP back. Again, this is in very general terms.
The wear test was complete joke and in no way mimics what happens in a two cycle engine it all.
Likewise the authors understanding of flashpoint is frankly ridiculous as is his misunderstanding of what ash is.
To top it off he "tests" the oils on a 4 cycle engine.
I stopped watching that stupid rubbish after that point and scrolled to the end tonhear his "conclusions".. Again, a complete joke, which is no supprise giving his test regime.
If I owned YouTube I would ban the guy.
40 : 1. They either smoke or scream.
Thank you for that insight!! I'm gonna have to check out the video.. Got a question for you, since you obviously know more about this than I do.. Are "old school" saws more forgiving on mix / type of oil / ratio than newer ones? Got a couple of older Stihl that don't seem to care what goes in the tank.. My newer stuff seems way more fussy. Just carbeuration?
LOL.. I used to run a lot of Nitro powered RC toys.. Yup!! had to re-tune when it got hotter in the afternoon. Hot air has a lot less density. Not sure if an RC carb is the same a saw carb.. RC carb? When you change the main jet, it effects the low jet.. Is that the same on a saw? Never seen that discussed??
It varies from saw to saw. Typically there’s 10-20% overlap. L screw affects about 10% of H. And vice versa
Interesting.. In the RC nitro carbs, the best explanation I saw was that the main ( high) was like the main tap on a hose, and the low was like the nozzle. If you leaned out the main, you had to rich up the idle ( low) to compensate.
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