Lean, Rich, Fuel or Oil Mixture Confused?

[rngrchad]

Alright somebody please help me out here. Is it true that talking about a saw running "lean" or "rich" can be interprated two totally different ways?
One could say: my saw is running a lean fuel ratio....they mean that it has a heavy oil concentration per amount of gasoline.

On the other hand one could say: My saw is running a lean oil ratio.....they mean that is has a small amount of oil concentration per amount of gasoline.

In both instances above the user describes his saw as running "lean". When most folks speak of lean they do not denote whether they mean lean in terms of fuel or oil. Ohhh forget it, I'm confusing myself now.

I always get kind of confused about the Lean/Rich statements people make. To me it ultimately comes down to carb settings. But just curious if I was the only one who scratches his head on this constantly. opcorn:

 

[stihl only]

For me, rich or lean is only about the air fuel ratio.

It's always 93 octane and Stihl Ultra, and that is a constant.

 

[rngrchad]

For me, rich or lean is only about the air fuel ratio.

It's always 93 octane and Stihl Ultra, and that is a constant.

Right, I agree. Same here. But how come whenever someone mentions oil fuel mixtures they always say that 32:1 is richer than 50:1. Is this a misnomer?

 

[PA Plumber]

Right, I agree. Same here. But how come whenever someone mentions oil fuel mixtures they always say that 32:1 is richer than 50:1. Is this a misnomer?

Even though 32:1 is a richer fuel to oil mix than 50:1, I understand the 32:1 will make the saw run leaner.

I also understand more fuel in the mix will help the saw run cooler.

If the above is wrong, hopefully someone will be along to get it all straightened out.

 

[rngrchad]

Even though 32:1 is a richer fuel to oil mix than 50:1, I understand the 32:1 will make the saw run leaner.

I also understand more fuel in the mix will help the saw run cooler.

If the above is wrong, hopefully someone will be along to get it all straightened out.

Cool, I figure Lakeside can spread some light on my confusion. Thanks.

 

[willsaw4beer]

Right, I agree. Same here. But how come whenever someone mentions oil fuel mixtures they always say that 32:1 is richer than 50:1. Is this a misnomer?

I agree, considering that I have to lean the jets when the oil is decreased (leaner carb setting for 50:1 as opposed to 32:1.) 32:1 is richer in terms of oil than 50:1 I guess.

 

[cjcocn]

Right, I agree. Same here. But how come whenever someone mentions oil fuel mixtures they always say that 32:1 is richer than 50:1. Is this a misnomer?

No, it is not a misnomer.

32:1 is richer in oil as compared to 50:1. This refers to fuel vs oil ratios and is important in that too little oil (a lean situation) can cause your saw to burn up (figuratively). Alternatively, too much oil can cause excessive carbon build-up, also not good for a saws engine.

Running a saw rich means increasing the fuel flow. In this case the reference is to fuel mix vs air ratios, and running a saw with too much air is also correctly referred to as a lean condition (with the same results).

HTH

 

[rngrchad]

No, it is not a misnomer.

32:1 is richer in oil as compared to 50:1. This refers to fuel vs oil ratios and is important in that too little oil (a lean situation) can cause your saw to burn up (figuratively). Alternatively, too much oil can cause excessive carbon build-up, also not good for a saws engine.

Running a saw rich means increasing the fuel flow. In this case the reference is to fuel mix vs air ratios, and running a saw with too much air is also correctly referred to as a lean condition (with the same results).

HTH

Alright. Thanks Cjcocn. I have a solid grip on setting 2stroke motors to run lean and or rich ....It just seems weird to me that folks automatically think that running 32:1 is going to automatically make a saw run richer when infact this is not the case. Right? It comes down to the carb settings.........I have to apologize, this thread is going to be terribly annoying. I can tell already. I think I've answered my question with you gentleman's help.

 

[flatpikr]

AND, the higher you go in altitude, the leaner you can run your saw. I think Oxygen is the key ingredient when considering how lean an engine is running. I had a Cessna 172 once and at 10,000 ft I had the mixture control almost full lean. RPMs will change with altitude changes if carb settings are not altered.

 

[leeave96]

I have thought about this too. I've got Stihl saws that are old enough that the owners manuals recommend 40:1 and newer one (and an Echo) that are50:1. But according to the manual if you do not use Stihl oil, then make the mix 25:1. The old Homelite is 32:1 and if not using Homelite oil, then 16:1.

I like 40:1 mix. To me lean/rich have to do only with fuel air mixture. My feeling is that for the most part, the oil goes along for the ride. The power is in the gas, not the oil. Sooooo, if you are using a heavier oil ratio, then compensate for that by adjusting the fuel/air ratio.

Thanks!
Bill

 

[cjcocn]

Alright. Thanks Cjcocn. I have a solid grip on setting 2stroke motors to run lean and or rich ....It just seems weird to me that folks automatically think that running 32:1 is going to automatically make a saw run richer when infact this is not the case. Right? It comes down to the carb settings.........I have to apologize, this thread is going to be terribly annoying. I can tell already. I think I've answered my question with you gentleman's help.

rngrchad

You are correct. Mixing your fuel to the proper ratios is only the first step in addressing the lean/good/rich question. The next step is ensuring that your carb is adjusted correctly.

I just found the other thread on mix ratios (40:1 and 50:1 started by Adirondack). Lakeside made an interesting comment regarding this very subject (post #9 in that thread) and certainly has me curious to learn more of which he speaks.

 

[rngrchad]

rngrchad

You are correct. Mixing your fuel to the proper ratios is only the first step in addressing the lean/good/rich question. The next step is ensuring that your carb is adjusted correctly.

I just found the other thread on mix ratios (40:1 and 50:1 started by Adirondack). Lakeside made an interesting comment regarding this very subject (post #9 in that thread) and certainly has me curious to learn more of which he speaks.

 

[Lakeside53]

Do you guys go out of your way to confuse yourselves?:greenchainsaw:

Adding oil to your gas does not make it richer.. it in fact makes the air fuel mix somewhat leaner unless you tune the carb to add more gas mix (or less air as in the case of some L circuits).

First, set the fuel/oil RATIO
Then tune carb to make the air fuel mix leaner or richer.


Then... practise not using confusing terms. Like coil when you mean "ignition"