A few years ago my Stihl Farm Boss engine lost compression. The Dealer said that to comply with EPA emissions, the Manufacturer sets the carb to run fairly lean and the piston scored.. I've been putting a little extra oil into the mix to try to prevent a re-occurrence on my new saw. Does anyone else add extra oil to their mix and if so what ration are you using?
2 cycle - 50 - 1 or some other mix
- Thread starter Garbanzo62
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I don't change the ratio, but I do listen to my engines, any time you here the whoop or have a lag in throttle response it's time for a carb adjustment
Highbeam
Minister of Fire
So since oil displaces fuel, I have been told that you are actually leaning out the mixture by adding extra oil. Lean/rich is not about oil but the fuel/air mixture.
My point is, to solve a lean running engine you adjust the carburetor. You don't add oil to the fuel.
My point is, to solve a lean running engine you adjust the carburetor. You don't add oil to the fuel.
EbS-P
Minister of Fire
50:1 vs 25:1 only chafes the amount of oil by 2%. Temperature and attitude probably have that much impact. Everything I’ve read is that current semi or full synthetic high quality mix oils are fine at 50:1. That said I don’t think there is anything wrong with a bit of extra lubrication as long as you are not getting much carbon build up.
I argue that carb tuning is more important that mix ratio 30-50:1.
I mix 37:1 for my Chinese G660 for milling. So that’s what everything else gets.
I argue that carb tuning is more important that mix ratio 30-50:1.
I mix 37:1 for my Chinese G660 for milling. So that’s what everything else gets.
You're confusing the gas-oil ratio with the fuel-air ratio. Adding more oil actually reduces the fuel-air ratio slightly. Oil is not fuel.
You need to adjust the carburetor to get the correct fuel:air ratio. Unfortunately since carburetors are not completely temperature compensated, the correct adjustment is different when it's cold out than when it's warm. So it's not a set it once and forget it kind of thing.
With my climate I adjust the saws a couple times a year , or when they need it. Once you know what to listen for you can tell when they are running too lean or rich. The owners manual (which you can download on Stihls web site) and the service manual (which you can get from the "beg for manuals" thread on arborsite.com) have instructions on how to tune the carb.
I run 50:1 fuel-oil ratio with high quality (not Stihl) synthetic oil.
salecker
Minister of Fire
BTW scoring a piston on the exhaust side can be a sign of lack of oil or of a lean fuel/air ratio. Often the lean fuel/air ratio will cause detonation (which you won't hear) and that often damages the top of the piston crown in a characteristic way.
Woodsplitter67
Minister of Fire
I run alot of 2 stroke.. I have 42 pieces of equipment that run weekly 2 years ago I switched the the echo RED ARMOUR.. its like 180 per case the last time I purchased.. the beginning of the year.. Since switching Iv had alot less carb issues and wiped motors.. its worth the money.. has fuel stabilizer in it also
Highbeam
Minister of Fire
I’ve been using the red armor for years. Seems to work. I am happy with echo as a company so trust their high end oil.
Woodsplitter67
Minister of Fire
I run mostly red max equipment.. I have some echo.. probably a 70/30 split.. Some of the red max stuff is way better.. the red max 2 strok oil just ok.. it was all good untill the blended fuel came along and the emissions restrictions are killing the small motors
I do this now too. I had to rebuild a ms290 because the piston was done. Not sure if any was from the previous owner but I turned it into a ms390. Haven't cut much with it but I'm not storing it with fuel in it anymore for long periods.
salecker
Minister of Fire
I run makita synthetic oil and have had good luck with it. I also just bought some amsoil that I run 50:1 and the deal I get, I can get it for the same price a stihl ultra. I quit using stihl ultra years ago because it stinks so bad and gives me a headache. Echo synthetic is another good oil too. Echo, makita, and amsoil are the only oils that don't give me a headache and don't make your clothes stink after a day off cutting. I also use nonethenol premium gas. But as said above, oil mixture is important, but the carburetor adjustment is everything on a 2 stroke. I also mix my fuel approximately 45:1
Isaac Carlson
Minister of Fire
50:1 vs 25:1 does not change the oil by 2%, it DOUBLES it. If amsoil can run 100:1, then any good oil can run at 50:1. Carb tuning is very important. I run 50:1 and check the tune on every tank.
salecker
Minister of Fire
50:1 leaves very little margin for error.Everything has to be spot on or bad things happen
mixing more oil gives you insurance from a meltdown
mixing more oil gives you insurance from a meltdown
Highbeam
Minister of Fire
Even if that melt down was caused by a lean air/fuel ratio?
Extra oil doesn't prevent a lean burn down. All it aims to prevent is a failure of the bearings or piston from lack of lubrication.
IMO 50:1 is fine in a modern saw, they aren't particularly high powered for their displacement, my 50cc saw makes a measly 4hp. Besides, if the engine is dismantled and all surfaces have oil then you are getting enough. Running the carb rich does however have the tendency to wash fuel off the crank and cylinder due to the extra fuel, which acts as a solvent.
Some engine designers have to get creative though to get a 2-stroke to live on 50:1. Snowmobile engines for example use oil injection and have direct oiling to the crank bearings and squirt oil onto the rod to then get thrown onto the cylinder, a complex system to maintain lubrication. But these engines are producing up to 165hp from 850cc.
IMO 50:1 is fine in a modern saw, they aren't particularly high powered for their displacement, my 50cc saw makes a measly 4hp. Besides, if the engine is dismantled and all surfaces have oil then you are getting enough. Running the carb rich does however have the tendency to wash fuel off the crank and cylinder due to the extra fuel, which acts as a solvent.
Some engine designers have to get creative though to get a 2-stroke to live on 50:1. Snowmobile engines for example use oil injection and have direct oiling to the crank bearings and squirt oil onto the rod to then get thrown onto the cylinder, a complex system to maintain lubrication. But these engines are producing up to 165hp from 850cc.
Isaac Carlson
Minister of Fire
50:1 and a good tune has worked well for me. I make a lot of long cuts and run ported saws. Been running 50:1 for 25 years and my saws are still going strong.
salecker
Minister of Fire
I took my info from a guy who rebuilds and ports saws.He has a no hassle warranty as long as you run 32:1
I also run a lot of vintage saws and other 2 stroke's
Oil is cheap,pistons,jugs and cranks are not.
I run the amsoil100:1 mix at 32:1,or any other oil i get.
I have never had any saw issues myself,i fix a lot of saws with issues.Once they are back to being alive i tune for my mix,use them for a while,then sell them with instructions on how to tune and that i mix 32:1.
So far none have come back.
I also run a lot of vintage saws and other 2 stroke's
Oil is cheap,pistons,jugs and cranks are not.
I run the amsoil100:1 mix at 32:1,or any other oil i get.
I have never had any saw issues myself,i fix a lot of saws with issues.Once they are back to being alive i tune for my mix,use them for a while,then sell them with instructions on how to tune and that i mix 32:1.
So far none have come back.
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