50:1 or 40:1?

My jonsered cs2171 that I got last summer is supposed to run on a 50:1 mix. I've never had any two stroke that ran on such a lean mixture. Is the EPA behind these new reccomendations? I'd like to get several years out of this one, and I've been mixing my gas 40:1 to be sure that I do. I would not have a problem buying synthetic 50:1 oil if I thought it would be better for my engine than what I'm doing now. Any advise on this subject would be appreciated. Thanks!

Where is Gasoline? Somebody page him.

do a search on oil mix ratio and you'll find lots and lots and lots of threads on this topic.......after reading most of them I've come to the conclusion that 50:1 is just fine with the new synthetics.

Which synthetic is best? Do a search on synthetic 2-stroke oil and you'll find lots and lots and lots of threads on this topic.......after reading most of them I've come to the conclusion that Stihl Ultra is as good as it gets for my use.

Pardon the sarcasm, it is meant to be good-natured, but I'm being kind compared to what some may respond with (because many feel this topic has been beaten to death).

Do a search and read the endless debate on oils and ratios. I'll summarize it:

Use high quality 2 cycle oil and fresh gasoline at an octane of 89 or higher. 50:1 is fine but if it make you feel better use 40:1.

My favorite ratio is 42.6666666:1 (3 oz/gal make it simple to measure)

P.S. 50:1 isn't lean. The more gas the richer the mix.

The correct answer is yes

davefr said:

P.S. 50:1 isn't lean. The more gas the richer the mix.

Click to expand...

not if the carb is lean. It won't matter if it is 1:1

50:1 is leaner than 40:1 in regards to oil content

Freakingstang said:

not if the carb is lean. It won't matter if it is 1:1

50:1 is leaner than 40:1 in regards to oil content

Click to expand...

Rich vs. Lean is always in reference to the fuel to air ratio. If the fuel mix has more oil and less gasoline then doesn't that imply it's lean. (ie less gasoline in the fuel that's mixed with air).

I could be wrong

davefr said:

Do a search and read the endless debate on oils and ratios. I'll summarize it:

Use high quality 2 cycle oil and fresh gasoline at an octane of 89 or higher. 50:1 is fine but if it make you feel better use 40:1.

My favorite ratio is 42.6666666:1 (3 oz/gal make it simple to measure)

P.S. 50:1 isn't lean. The more gas the richer the mix.

Click to expand...

Freakingstang said:

not if the carb is lean. It won't matter if it is 1:1

50:1 is leaner than 40:1 in regards to oil content

Click to expand...

Ah, the great debate. Oil is a lubricant, fuel is a coolant. Even at 32:1, you can burn a 2 stroke up...plenty of oil for lube, but if the carb is not properly adjusted, a lean condition will exist = creating excessive heat due to lack of fuel = burning the oil and eventually melting the piston.

Personally, I don't like all the smoke, so I run straight gas :monkey:

davefr said:

Do a search and read the endless debate on oils and ratios. I'll summarize it:

Use high quality 2 cycle oil and fresh gasoline at an octane of 89 or higher. 50:1 is fine but if it make you feel better use 40:1.

My favorite ratio is 42.6666666:1 (3 oz/gal make it simple to measure)

P.S. 50:1 isn't lean. The more gas the richer the mix.

Click to expand...

I usually do this also, its easier to put 3 ounces in a gal than 2.56 ounces or whatever.

Do it this way and sleep soundly

50:1 was the recommendation 10 years before the EPA reared its ugly head.

I bought one of these for measuring out the oil for my mix. Saves a lot of brain work.

http://www.baileysonline.com/itemdetail.asp?item=17090+01&catID=150

We need to get all the oil threads on a sticky.

Urbicide said:

I bought one of these for measuring out the oil for my mix. Saves a lot of brain work.

http://www.baileysonline.com/itemdetail.asp?item=17090+01&catID=150

Click to expand...

Me too.

One way to look at this is is stihl, husky ect all say to mix 50:1. they are gonna set up there product so there is some room for error. meaning a little more or less isn't going to kill any thing. the motorcycle i used to race we ran 100:1 never had any bearing problems.and this thing was modded to the limits! If you feel safer at 40:1 then run that but you can asure that 50:1 will not cause your saw to burn up premature. Joe

50:1 in "all" my saws no probs so far, they look clean inside and run very strong

Its been 20 years since I've done much dirt bike riding, so I don't know much about dirt bike ratios know days. Back then I used Yamalube 2R ( I think it was) oil at 32:1 in an air cooled bike- that's what they suggested. I assume they still suggest 32:1 for the new bikes- Honda does look at the link below.
So why do they suggest to run some engines on 32:1. Look at the air cooled kart engine its 20:1 with a synthetic based oil. Why??????? Maybe 50:1 for saws is all about EPA.

http://www.yamaha-motor.com/sport/products/modelspecs/464/0/specs.aspx
http://powersports.honda.com/the_go...Pro-Honda+HP2+Racing+Oil+(32:1)&TheGoodsDir=0 Looks like they're still using that ratio.

Airecon said:

Its been 20 years since I've done much dirt bike riding, so I don't know much about dirt bike ratios know days. Back then I used Yamalube 2R ( I think it was) oil at 32:1 in an air cooled bike- that's what they suggested. I assume they still suggest 32:1 for the new bikes- Honda does look at the link below.
So why do they suggest to run some engines on 32:1. Look at the air cooled kart engine its 20:1 with a synthetic based oil. Why??????? Maybe 50:1 for saws is all about EPA.

http://www.yamaha-motor.com/sport/products/modelspecs/464/0/specs.aspx
http://powersports.honda.com/the_go...Pro-Honda+HP2+Racing+Oil+(32:1)&TheGoodsDir=0 Looks like they're still using that ratio.

Click to expand...

Well. When I had bikes I either ran 32:1 in my CR250's, sometimes 40:1 if I felt I wouldnt be doing much wide open. In my KDX I always ran 40:1

I figure with a saw thats being run wide open all day 40:1 instead of 50:1 is more appropriate. I dont run stihl oil because its a waste of money =].
I usually run some kinda ok oil from an auto parts store. Rarely gas station oil.


Mind you, the more oil you add to the mix the leaner the saw will run.
IE if tuned using 50:1 it will actually run leaner on 32:1.
Reason being there is less gasoline per volume in the fuel... Stoich is 14.7/1 A/F with 50:1.. 2/100ths of the fuel and approximately 0.294% of the intake charge is mix oil. With 40:1 2.5/100ths of the fuel mix and 0.367% of the intake charge is oil. Its a slight difference that can be used to alter A/F ratios ever so slightly.. with fixed jet carbs it can make up a difference between jet sizes. Racers use very specific ratios to tune for stoichiometric A/F ratios & max power. The average saw user wants the A/F ration a little rich anyways because the saw will run cooler and longer.

Basicly, stoich might be different with premix than straight gas as well.
More of a topic for the hotsaws forum.

ya, as you add more oil to the mix there is less gasoline content so you need to richen the jetting slightly or it runs leaner.

so richer is leaner and leaner is richer.

From all the posts I read here and other forum, together with 6 old engine I took apart, Other than not having oil in the gas, deposits on piston, sticking rings are more likely to end an engine's life than just wear out. Before putting a lot of oil into the gas, take this into consideration. I personally went from 30:1 down to about 45:1 just to balance out the pros and cons.

This is a thread on oil deposit test. ONe of very few test that is not ran with a biasd mind. Don't read too much into the result as the condition of running represent one situation only.....WOT for 6 hours. Also most important, the tester adjust the air fuel mix to keep the temperature constant which you might not be able to. Just a piece of info.

http://www.geistware.com/rcmodeling/articles/oil_test/index.htm

Bottom line, use JASO FD oil, mix close to recommended ratio, few drops more if you really want to!!! Do recommended maintenance. Check to make sure carb is not too lean because that will kill your engine. Then don't worry about it anymore.

As for me. I use Echo Power Blend just because I am tired of searching anymore. I check the plug ofter and note if the color get lighter ( fuel get leaner and hotter ). I don't want to have anything to do with 100:1, that's it.


Good luck

well im no amsoils fan but what i pulled from the test the oil rich mixtures cleaned the deposits better than the leaner mix with correct jetting.


see no reason not to run 40:1 other than cost given these results.