oil mixture confused!

[314epw]

I heard that a 40 to 1 mixture burns hotter then a 50 to 1 mixture.I thought that little extra oil would help these high rev machines.Set me straight Please
I'm getting old and gray and can't remember ----.
Thanks
Ed:bang: :bang:

 

[THALL10326]

I heard that a 40 to 1 mixture burns hotter then a 50 to 1 mixture.I thought that little extra oil would help these high rev machines.Set me straight Please
I'm getting old and gray and can't remember ----.
Thanks
Ed:bang: :bang:

Good point there. The replies should be interesting on that question. I just run whatever the saw suppose to run and have yet to have any problems.

 

[NWCS]

i use 40:1 in ALL my 2cycle equipment, from my 21cc echo brush to my woods port 036 Pro, and vintage saws. you just have to make sure the carb is adjusted properly for it. every ratio change requires a carb adjustment to match it. i have not had any heat problems at all.

 

[rupedoggy]

Let's take this to its illogical conclusion. If more oil burns hotter, straight oil will burn hottest of all... NOT!! I know straight oil won't burn in the two stroke, but see the point? More oil protects better and does not burn hotter. My two cents. Mike

 

[cord arrow]

I heard that a 40 to 1 mixture burns hotter then a 50 to 1 mixture.

you have been correctly informed.

more oil in a given ratio means less fuel. the less the fuel the hotter the burn. (leaner)

having said that, these little archaic engines could really care less.

now, on our race bikes, or some of these hotsaws, tuned to within an inch of their lives, it does make a difference.

but, on a stock chainsaw/weedeater/hedgetrimmer/blower, find a happy medium, mix 'em all the same. less hassle.

you'll find, the smaller the motor, the more the effect. doesn't necessarily sound right, but has been my experience.

on small blowers and perhaps like a two-cycle roto-tiller, expect to pull the limiter caps when going to a leaner (more oil) mixture. there's just not enough lee-way with the stock settings.

 

[cord arrow]

straight oil will burn hottest of all...

correct again. given huge compression and a constant ignition source....

...ie, DIESEL???

 

[cord arrow]

please let us remember, gentlemen, that MIXTURE refers to AIR & FUEL.

nothing else. has absolutely NOTHING to do with oil.

 

[rupedoggy]

OK I got one foot in this tar baby and am not a quitter.
1. Who said anything about not adjusting the mixture? That's what the mixture screws are for.
2. If you think gasoline doesn't get hotter than diesel, try burning some gasoline in you 22:1 motor. Burns quicker and that makes for hotter. I know the BTUs of diesel are more but getting it out is not so easy.
3. I have some old saws that have sat for 20-30 years. When taken apart they still have good pistons/cylinders and oil inside. Why? They ran 16:1 (and didn't seem to overheat). The new motors are the melt downs not the old ones. I know global warming!
4. One last thought. If the saw people want us to burn clean and cool we should use alcohol.
Mike

 

[ShoerFast]

Read the Mans concern again,,,,,,,,

I heard that a 40 to 1 mixture burns hotter then a 50 to 1 mixture.I thought that little extra oil would help these high rev machines.Set me straight Please
I'm getting old and gray and can't remember ----.
Thanks
Ed:bang: :bang:

We're talking about 6/10th of an ounce difference in 128 (fld) oz.,,,,,
It would make more of a difference how much string , a trimmer was sporting, what way the wind was from on a blower, or how sharp the saw chain is then the different thicknesses of a bar-keeps fingers.

Kevin

 

[cord arrow]

I know the BTUs of diesel are more but getting it out is not so easy.

yeah, that's where the huge compression & constant ignition source come in. i was making a point.

They ran 16:1

they had to. oil was junk. the LITTLE hole (jet), the one that delivers the FUEL into the BIG hole (carb throat) was much bigger. given that the ratio of fuel to oil was 16:1, it had to be, don't ya think?

now, do this. take your whatever that runs at 50:1 & mix it at 16:1.
put 'er under a full load.
now, why do you suppose it detontated?
ya suppose the LEAN condition had anything to do with it? the LITTLE hole (jet), could not possibly supply enough fuel to the BIG hole (carb throat), because too much space was consumed (occupied) by the OIL.

which, i believe, was the original question.

 

[rupedoggy]

Oil was junk? Didn't it come out of the ground, same as today? Wasn't it refined, same as today? If more modern additives are helping oil do the job longer or better, I will throw in with you.
As for the old saws using a different jet, that just is not so. I have fitted several carburetors from old 090s, several Mccullochs and Homelites onto newer saws and the settings are the same. Those needles that adjust the mixture always allowed me enough lattitude to make any stock type saw run too rich or too lean.
Detonation problem. You may indeed experience detonation problem at extreme oil rich ratios. That is caused by lower octane. As the oil is added the octane goes down. Once oil and gasoline are mixed they don't take up individual "spaces" they are a mixture and different than either was before the mix. Mike

 

[Lakeside53]

Diesel in chainsaw

Funny you guys should be talking about this... Big local lumber year uses an MS880 as part of their "precision cut-off saw". Cuts an entire unit of 2x4 in one swipe.

Monday - enter the new guy - 4 hours on the job - fills the saw with diesel instead of mix. Ran progressively worse an worse for 15 minutes and stopped, dead.


Cylinder bad, piston melted... New P&C = $420... Plus labor...

 

[NWCS]

cord, you missed one key aspect about ratios. its the viscosity that plays a key role to lean or rich. 32:1 is thicker and therefore flows slower than 50:1 thats why you have to re-adjust the carb.

 

[bump_r]

32:1 is thicker and therefore flows slower than 50:1 thats why you have to re-adjust the carb.

BWAHAHHHHAHAAAAHAHA!!!.... oh, you were serious... sorry.

I am following this discussion with great interest, as I just mixed my first can of 40:1 using premuim unleaded and Stihl "orange bottle" oil. So far none has gone into a saw, just my poor ole FS36. It's run about 5 minutes with 40:1 wearing way too long strings, so over-revving didn't happen, but I sure don't want to fry the thing. With no tach and no experience tuning by ear, I'm wondering how critical a re-tune would be for it and my saws with such a small change in mix.

 

[Lakeside53]

With no tach and no experience tuning by ear, I'm wondering how critical a re-tune would be for it and my saws with such a small change in mix.

40:1 or 50:1? It isn't ... saws (or FS36 ) shouldn't be tuned to where they are so lean that any tiny variation in fuel, mix or weather will push them over the edge.... I run mine on the "fat" side, and don't sweat it. My mixes are all over the place from about 40 to 50 to one. Occasionally less then 40.

 

[bump_r]

Thanks, Lakeside - I'll just listen for the burble and go from there. One day I'll get a tach... One day...

BTW - I've caught mentions on AS that Stihl farmed-out the production of my beloved FS36 - did they farm out just the manufacture or design as well? And to whom?

 

[cord arrow]

"I know, I did a search." cord arrow, circa 2006

my crowning moment of glory. i am so proud.

 

[Farley9n]

Fs 36

Hate to break it to you bump but your FS 36 engine is a Ryobi wearing a Stihl costume. There are some differences but the main internals are the same....Bob

PS...FS 44 also!

 

[THALL10326]

Hate to break it to you bump but your FS 36 engine is a Ryobi wearing a Stihl costume. There are some differences but the main internals are the same....Bob

PS...FS 44 also!

FS40's too and all three are uhhhhhhhhhhhhhhhhhhh, well lets say they aren't fun to work on, grrrrrrrrrrrrrrrrrrr.

 

[Lakeside53]

FS40's too and all three are uhhhhhhhhhhhhhhhhhhh, well lets say they aren't fun to work on, grrrrrrrrrrrrrrrrrrr.

Yes... I give really good trade in on them so I don't have to work on them..