2-cycle mix ratios

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Aug 2, 2018
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growing up i remember most small 2 cycle engines running a 32:1.. 4 oz to 1 gal, i bought poulan backpack blower it calls for a 50:1 mix i believe it's 2.6 oz to 1 gal.

does this have something to do with the epa using less oil now a days.. i would think this would cause more wear having less lubricity in the fuel.

can i use a 32:1 mix or just move on and keep with the 50:1.

thanks
 
Maybe the mfgs have determined with the new oils 50:1 is sufficient and more oil doesn't reduce wear; As a thought experiment why not 10:1?

Just hypothesizing
 
i am sure the muffler and spark plug won't foul up as much with a synthetic oil and a 50:1 mix. i'll just roll with the 50:1 as usual manufacture knows best
 
Most likely an EPA mandate but the synthetic 2 stroke oils have vastly improved. In Colorado 7% of the air pollution is from lawn equipment.
 
Oils and equipment have improved over the years.

A few years ago on another site someone had some info from Stihl on their synthetic oil that they tested it at 100:1 with no issues but keep 50:1 because they still meet emissions there and people are hard to change.
 
I usually see 50/1, some synthetic says 100/1. Most mixes I use are 50/1. I may error slightly on the ‘rich' side, nothing crazy.
 
Originally Posted by Oildudeny
growing up i remember most small 2 cycle engines running a 32:1.. 4 oz to 1 gal, i bought poulan backpack blower it calls for a 50:1 mix i believe it's 2.6 oz to 1 gal....does this have something to do with the EPA using less oil now a days.. i would think this would cause more wear having less lubricity in the fuel..... can i use a 32:1 mix or just move on and keep with the 50:1.?


Where have you been??!??!

Pretty much all 2-stroke outdoor power equipment has been at 50:1 for about 20 years (or longer) now...

I haven't seen 32:1 recommended on any 2-stroke OPE since about 1986 or so.....

.

What year was the last 2-stoke Lawn-Boy made? Some time in the 1990's?
 
The EPA outlawed 2 strokes in walk behinds around 2003. I still use three Toro (Suzuki engines) self-propelled that are two strokes quite heavily during mowing season in my small lawn-care business.

I'm now using Stihl HP-Ultra since some engine service a couple of years ago mixed around 40:1. No issues with exhaust port or muffler carbon build up at all.

Used Super Tech for many years prior to that with no issues also at about 40:1.

My selling dealer in 2003 advised to mix it rich with oil and check the exhaust ports for cleanliness. Wise advice from an experienced man.
 
I have (well, HAD until it was stolen) a 2003 Yamaha XLT 1200 Waverunner. 3 cylinder 2 stroke rated at 155 hp. I recall reading about the variable rate oil injection, which varies from 200:1 at idle down to 50:1 at 50% throttle, and 32:1 at about 80%+ throttle. The oil pump was this little gizmo with cams and levers for the variable part, quite ingenious although I think it was standard in Japanese 2 strokes for a long time. I really miss that toy - ph@ck the bast&rd that stole it.
 
I tend to mix each 15 ounce tank of fuel each time I fill up and I have been fascinated by the lubrication system on these tiny engines for ages. I have a Husqvarna 125B handheld blower that I like to play with and run on the different brands and mixes just for curiosity sake.

One thing I have noticed is that when I use Amsoil Saber at their prescribed 100:1 mix ratio and run the blower non-stop for a full 15 ounce run I will lose 300-400 RPM. I use an Oppama PET-1100R tachometer and have a home made test stand for the blower so it can run unattended. I don't experience this with other oils mixed at 40:1 (my determined optimum mix ratio for a small OPE handheld item).

I get flack from the Amsoil crowd about this but I can repeat this phenomenon over and over. I can only guess that the piston is expanding more during the high heat generated run.

I have mixed as rich as 16:1 and as lean as 125:1 and never fouled a plug. I think the modern ignition systems have done more for this improvement than anything else.

My only detrimental operation was when I bought some castor oil from the pharmacy and used it at 32:1. In one tank of fuel I seized my piston ring in the piston. This required replacement of the ring only (broke it during removal) and cleaning the ring land. This blower is a one ring design and I lost so much compression from the ring seizure that the engine stopped running and would not restart.

So I have determined that I will only use the Saber at 100:1 in something that only runs for a few minutes and then is shut down. My string trimmer meets that requirement. I do a lateral movement check on the rod bearings and have not noticed any abnormal lateral movement so I don't feel bearing wear has not been an issue. My chainsaw and blower have no catalyst in their exhaust, my string trimmer and hedge trimmer are new enough that they do have a catalyst in their exhaust.

I think it's wise to stick with a ratio that is close to what the OEM recommends. A 50:1 should be safe for anything spinning less than 10,000 RPM. My chainsaw hits 12,000 RPM but all of my other equipment revs 8,000 or less. The oil brand doesn't seem to matter. I do LOVE Red Armor and Torco GP7. These are two impressive lubricants.
 
Originally Posted by FowVay

One thing I have noticed is that when I use Amsoil Saber at their prescribed 100:1 mix ratio and run the blower non-stop for a full 15 ounce run I will lose 300-400 RPM.


I'm not convinced this tells us anything about the oil. After all, by changing the fuel:eek:il ratio you also alter the air:fuel ratio in the engine. By running the oil at 100:1 the fuel:air ratio becomes richer, and rich engines usually run slower than leaner engines.

Running the oil at 100:1 might still actually be bad for the engine, I don't know. I'm just saying this way of testing has too many other variables and doesn't tell us that.
There is probably no way to fully eliminate the influence of the varying air:fuel mixture, but maybe the impact could be reduced by letting the engine warm up for 15 minutes and the tuning the carb to get the maximum RPM possible for each test run. But then again this will only tells us the maximum RPM the engine achieves and nothing about the wear in the engine.
 
Originally Posted by FowVay
My only detrimental operation was when I bought some castor oil from the pharmacy and used it at 32:1. In one tank of fuel I seized my piston ring in the piston. This required replacement of the ring only (broke it during removal) and cleaning the ring land. This blower is a one ring design and I lost so much compression from the ring seizure that the engine stopped running and would not restart.


Drug store castor is different from what they use in 2 stroke oil. I tried that one time as well lol.
 
Originally Posted by Warlord

Drug store castor is different from what they use in 2 stroke oil. I tried that one time as well lol.


Yes, but I wanted to see what it would do. I keep a 16 oz. bottle of Blendzall racing castor on hand because it's just amazing. As for the comment about the air/fuel ratio after altering the oil/fuel ratio - naturally the engine has be to returned to run with such drastic changes. It's all compensated for.

I do have some Opti-2 in the individual packages that mixes at 71:1 (1.8 ounces per gallon) and I haven't tried mixing it at 100:1 and checking for RPM drop. That will be my afternoon task today.
 
Originally Posted by FowVay
Originally Posted by Warlord

Drug store castor is different from what they use in 2 stroke oil. I tried that one time as well lol.


Yes, but I wanted to see what it would do. I keep a 16 oz. bottle of Blendzall racing castor on hand because it's just amazing. As for the comment about the air/fuel ratio after altering the oil/fuel ratio - naturally the engine has be to returned to run with such drastic changes. It's all compensated for.

I do have some Opti-2 in the individual packages that mixes at 71:1 (1.8 ounces per gallon) and I haven't tried mixing it at 100:1 and checking for RPM drop. That will be my afternoon task today.


Nice! I actually just picked up some of the Opti-2 today. I only have 1 more bottle of my Husqvarna oil, and a commercial mowing customer of mine swears by the stuff. His 2 cycle equipment is all fairly old so I figured it must be a decent oil.
 
There was a time I maintained mixes of 16:1, 32:1, 40:1, because each piece of equipment required it. I now use 32:1 for everything. Equipment may have improved, but I still use old equipment. My chain saw even requires leaded gasoline!

Good riddance to 2-cycle lawn mowers. They were gas pigs.
 
I used to weed wack 3 acres on the side of the hill for a fire break for the house I usually planned on 3 hours per day . I found 32 to 1 gives more power than 40 or 50 to 1 and the exhaust stayed clean.
 
Once I use up this bottle of cam 2, 2 stroke oil I'll switch to a synthetic with the fuel stabilizer already blended in.
 
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