I'm not saying anything one way or the other on Amsoil, as i have no first hand experience, but their mix ratio suggestions make me nervous. Sorry that it will now turn into an Amsoil bashing thread? Anyone have any other examples of oils that suggest super lean mix ratios that I could use instead?
Running alittle rich
- Thread starter stihlgoin
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THALL10326
The Champ
I understand the math but not the logic. I've never seen a lean siezure from too much oil in the mix if the carb is adjusted right. I have however seen many lean siezures from lack of oil in the mix. In math theroy you are correct 100% but in saw theroy those scored cylinders say we wish he had put some more oil in the mix,lol.
yep 100/1 makes me nervous to.. Where is Ben??:bang: :bang:
Lakeside53
Stihl Wrenching
TimberPig said:
The "bashing" is very light hearted... unless Ben comes along
Lakeside53
Stihl Wrenching
04ultra said:
Someone PM him - he's missing out...
Lakeside53 said:The "bashing" is very light hearted... unless Ben comes along
You said it spot on ..
THALL10326 said:
I agree with you 100% that lean fuel/oil mixes often cause seizures, but it is not due to a true lean siezure (too hot from a lean air/fuel mix, piston starts melting and seizes) but from a lubrication failure due to inadequate oil to properly lube and protect it.
The question asked if a more rich fuel/oil mix would richen the air/fuel mix which it does not.
THALL10326
The Champ
All I'm saying is common knowledge. If you see a saw pouring out smoke and the muffler has oil running out of it and the carb is set one turn out on the high and low side then it tells me there is too much oil in the mix. A clogged muffler and exhaust port is the result of too much oil in the mix. We call that a rich mix even though by math more oil leans out a fuel/oil mix gas wise but not oil wise. That oil in that mix goes through the carb as well as the gas. If you take a perfert running saw and doulble the oil in the gas and it starts pouring out smoke 999 people out of a 1000 would say the fuel mix is too rich. Correct?
Max said:
Sorry, but you asked for advice. That saw is exibiting symptoms of a lean mixture or a small air leak. Adding oil to the mix will not fix either of those two problems and could in fact make them worse.
All the best, John..
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THALL10326
The Champ
Not bumping heads Fred. I'm just talking old school with math and in theroy and math everyone is right. I'm not arguing with the guys for they are correct but old school uses a different language, thats all. This site is great.
THALL10326 said:
Yes a fuel/oil mix with lots of oil in it is called a rich mix.
An air fuel mix with lots of gas and little air is also rich.
They are two separate things that due to terminology get many confused. Nowhere did I say they were the same thing.
So long as the carburetor adjustments permit, any reasonable ratio of fuel/oil mix should be able to be tuned to run properly and cleanly. If it begins slobbering oil out the muffler, then it is not completely combusting the oil. This is as you say can be a sign that there is more oil in the fuel/oil mix than is required for the application. It can also be a sign that the carb is set too rich and the engine is not burning hot enough to combust the oil. In the case where the saw is slobbering oil with the high speed screw only 1 turn out, it is evidently getting more oil than necessary, although if it was running in that state, plug fouling would likely also be an issue. It also would likely not be running very well, both signs it needs adjustments to be made.
THALL10326
The Champ
Timber I'm With Ya On This. I Understand Exactly What Your Saying, No Fussing With Ya On That. However What Max Said Was He Had Mixed His Fuel Alittle "strong" Meaning I Assume He Added Abit More Oil In His Gas Than Reqiured. He Never Said He Took Out Any Gas. He Asked If It Would Make His Saw Run Alittle Rich And The Answer Is No To A Certian Degree. If He Dumped A Quart Of Oil In A Gallon Of Gas Then Yep His Saw Would Be Running Real Rich, With Oil, Not Lean With Air /fuel Ratio Because He Never Said He Adjusted The Carb Settings. Settings Being The Same Means The Only Thing That Has Changed Is The Extra Oil He Put In The Fuel Mix. He's Merely Using More Oil And That's A Rich Condition, Not A Lean One. Air/fuel Ratio As You Say Is Not Fuel/oil Mix, They Are Two Different Things Entirey. By Joe I Think We're In Agreement Aren't We,lol
THALL10326 said:
Ok, ignoring the oil in the mix for a second. If you have a container of fixed volume that can hold 1 litre of air, plus the required amount of fuel for the correct ratio (hopefully metric doesn't confuse you, it makes the math easier) and you add to it 1/16 as much fuel or 0.0625L to get the correct air fuel ratio (normally somewhere around 15:1-16:1 I believe). Then you burn it.
This is essentially what your carburetor is doing, the oil doesn't factor into the air/fuel ratio that the engine burns because that is not its purpose. The purpose of the oil is as lubricant, although it can become too much of a good thing as you say, and as I get into below.
Now take that same litre of air, and reduce that 0.0625L of fuel by adding some oil, say using 32:1 mix. This gives us 0.00195L of oil in the mix, which can round to 0.002L. This oil being added to that same amount of fuel needed for the correct ratio of air to fuel will reduce the amount of fuel in the system. The end result is we have 0.0605 L of fuel mixing with the air. Now our 16:1 air/fuel ratio has become 16.52:1, because of the reduced amount of gas in the fuel/oil mix. This is the exact same thing that happens when you turn in the screws too much and your saw burns up (because you reduced the amount of fuel in the air fuel mix). This is the cause of a lean air/fuel ratio.
When you richen your fuel oil ratio by mixing it "strong", you reduce the amount of fuel in the air fuel mix indirectly as a consequence.
The "rich condition" you are thinking of is because there is too much oil in the engine, and it cannot efficiently combust the mix because of it. It is not the same thing as a rich condition caused by too much fuel in the air/fuel mix, as is correctly termed a rich condition. The problem here is that the terminology is being incorrectly used and applied.
A rich fuel oil mix will lean the air fuel mix.
A lean fuel oil mix will richen the air fuel mix.
A lean air fuel mix causes a lean engine running condition.
A rich air fuel mix causes a rich engine running condition.
A rich fuel oil mix leads to inefficient combustion and blubbering sputtering and spooging, because the engine cannot burn off the excess oil. This does not mean the air/fuel mix is rich, as it is actually lean. It is a byproduct of too much oil reducing the efficiency of combustion, not a rich running condition.
A lean fuel oil mix will lead to seized pistons and burnt rod bearings, the engine will run hot, the lubrication will fail and the engine parts begin to melt and seize, all because the oil supply to reduce friction is inadequate. This can happen in spite of adequately rich air fuel mixes that do not cause a lean burndown.
Assuming we are somewhere in the spectrum of mix ratios between blubbering from too much oil polluting the air fuel mix, and a seizure from too little lubrication, the air/fuel ratio is what is important, and is what you control when you are adjusting the carb screws.
The biggest issue here is that the terms rich and lean are used for the two different items, fuel/oil mix, and air/fuel mix. Then because they work completely backwards of each other, people misuse them, confuse them, and you end up with a two page debate because of it.
THALL10326
The Champ
Timber somehow I knew you was going to go into great detail explaining the theroy and use all sorts of numbers and math and calculations to prove your point. Those are the reasons we have a two page debate,lol. I understand exactly what your saying and you are correct 100% except for that first line of yours, "ignoring the oil in the gas for a second". Thats where your off track. You can't ignore it if its part of the equation we are talking about. Using your math would it be a fair statement to say, based on your theroy and math calulations that the richest fuel of all would be one of pure gas and no oil at all?, although with no oil in it you couldn't call it a mix. It would be according to your math the very richest it can poissbly be and totally worthless to any chain saw. Remember now we are talking the fuel that is going to run the engine, the fuel in the tank, not the fuel being pushed through the carb behind air flow or the air/fuel ratio but just the fuel in the tank. Based on your math of volumn and calcualtions the richest that fuel could possibly be is not to put any oil in it at all. I don't think any saw would agree with or run very long with your rich fuel calculations even though they are correct as you point out. I will say your quite good on a calculater but I won't loan you a saw,lol..
If you put too much oil in the mix, it will blubber and foul out the plugs. If you put too little oil in it will seize. There is no way to operate a 2 cycle motor without putting oil in the mix and have it live, but yes, the richest air fuel mix would be one with no oil mixed in it. As any clueless person who has ever straight gassed a saw knows, the saw seizes. The problem is despite a rich air/fuel mix, there was no lubrication. At the opposite end of the spectrum is a blubbering saw that despite a lean air/fuel mix cannot run well enough because of too much oil, to be able to burn down.
The fuel in the tank is not what determines the air/fuel the engine receives is, it is the fuel passing through the carburetor. That is where all this theory and math actually matters.
The fuel in the tank does determine how much fuel relative to oil is delivered. This determines how much lubricant the engine receives for the volume of mix passing through the carb. As you increase the amount of gas in the fuel passing through the carb, the oil drops and vise versa. there is no way to avoid it. Thats why we have carb adjustment screws, is so that we can vary the air/fuel ratio to what the engine desires, to compensate for fuel/oil mix, altitude, temperature, humidity and air pressure.
If you properly mix your gas at any sane ratio, and properly adjust your carburetor to that mix, all this head bashing is of little consequence.
Now as to your thoughts that I'd burn down your saw with an ultra lean mix, it wouldn't happen. 50:1 is leaner than I prefer. 32:1 to 40:1 is my preference. More lube only hurts a saw if it cokes up the bearings, and carb adjustments take care of the air fuel ratio as they are intended to. But I have no need to borrow a saw anyhow, as I have perfectly good saws of my own.
The fuel in the tank is not what determines the air/fuel the engine receives is, it is the fuel passing through the carburetor. That is where all this theory and math actually matters.
The fuel in the tank does determine how much fuel relative to oil is delivered. This determines how much lubricant the engine receives for the volume of mix passing through the carb. As you increase the amount of gas in the fuel passing through the carb, the oil drops and vise versa. there is no way to avoid it. Thats why we have carb adjustment screws, is so that we can vary the air/fuel ratio to what the engine desires, to compensate for fuel/oil mix, altitude, temperature, humidity and air pressure.
If you properly mix your gas at any sane ratio, and properly adjust your carburetor to that mix, all this head bashing is of little consequence.
Now as to your thoughts that I'd burn down your saw with an ultra lean mix, it wouldn't happen. 50:1 is leaner than I prefer. 32:1 to 40:1 is my preference. More lube only hurts a saw if it cokes up the bearings, and carb adjustments take care of the air fuel ratio as they are intended to. But I have no need to borrow a saw anyhow, as I have perfectly good saws of my own.
THALL10326
The Champ
Timber I'm liking you more and more. Look at your last paragraph on your last post. You say 50:1 is "leaner" than you perfer. You perfer 40:1 or 32:1 which means those two mixes are what, RICHERRRRRRRRRRRRRR. Thats all I've been trying to say.
THALL10326 said:
Yes they are richer fuel/oil mixes. I then adjust the carb to richen the air/fuel mix so that it is correct. This goes back to the separate air/fuel, fuel/oil mix statements. That to richen the fuel/oil mix, you add more oil, and to compensate for the extra oil you turn out the carb screws to bring the air/fuel mix back to where it should be. Without the adjustment, your rich fuel/oil mix slightly leans your air/fuel mix.
Assuming a 50:1 mix as a starting point.
THALL10326
The Champ
Timber thats exactly what I've been trying to say. The more oil you put in the gas means the mix is richer. We are now in 100% complete agreement my friend. I have 16 Stihl's out in the shed, every size from the 064 to the tiny 020t. Your now welcome to any of them.
16gauge
ArboristSite Operative
Oh my god...now that was interesting...for a little while. I'm thinking the quality of the fuel, both gas and 2-cycle oil is a problem in many cases of locked up saws. Poor storage, etc. adds to the problems. Used 36:1 up to 50:1 in my saws over the last 25 years and never had a siezure problem. Maybe because I have a little screwdriver, I clean fuel and air filters often. I also am willing to sacrifice the extra 500 to 1000 rpm to get a nice burble at wot. There's an old tale about the tortoise and the hare
