25:1 mix

[StihlKiwi]

From the Stihl manual! mix fuel @ 50:1 with Stihl oil! 25:1 with other brand oil! No mention of re-tuning what so ever. How many people would you think have not taken this fuel ratio recommendation when using 'other' brands of oil?
If oil isn't fuel can someone tell me what was spewing out of hundreds of oil rigs on fire during the Gulf War?

My jug of Stihl oil is actually Castrol oil "specially formulated for Stihl" (different colour dye). Should I split the difference and run it at 32.5:1 just in case the "other brand" bits in it don't lubricate enough?

 

[splitpost]

I run 25:1 in all my 2 stroke gear,i don't see any carbon fouling when running them hard,in fact they are very clean inside,and yes I have pics to prove it ,I think where the majority of problems running 25:1 come from is old mate cutting some wood or trimming the wifes hedges etc ,they don't run it long enough to actually get hot,i see it mostly on my tanaka petrol drill,it fouls and carries on but it does have a carb from a ms260 on it:hmm3grin2orange:

 

[scallywag]

Ok my stihl 084 is recommened to run on 40:1, my 090 @ 25:1, would you guys say i should run these saws at 50:1 ?
I have never used stihl oil, running motul at the prestent.

 

[husq2100]

Ok my stihl 084 is recommened to run on 40:1, my 090 @ 25:1, would guys say i shoud run these saws at 50:1 ?
I have never used stihl oil, running motul at the prestent.

Can you keep the goal posts in one spot so I know where to score.............You made the bold statement of runing a saw (taken as any, as no one model was specified) would burn, blow up at 50-1. Basically BS, but yes there will always be the exception, which in fact is what proves the rule.

I would say run them at what ever the heck you want, just tune them accordingly. If you think your 090 manual was written with the knowledge of modern oils then think again.

I personally run all my everyday stuff at 40-1 with a blend of husky/maxima927 oils. And you may be suprised to hear that I agree to run the bigger saws in the hotter parts of Aus at less than 50-1, that is to say in the area of 32/40-1, but of coarse I would recommend tuning them to suit. But that still does not prove or support the fact that saws will blow up at 50-1.

 

[husq2100]

I run 25:1 in all my 2 stroke gear,i don't see any carbon fouling when running them hard,in fact they are very clean inside,and yes I have pics to prove it ,I think where the majority of problems running 25:1 come from is old mate cutting some wood or trimming the wifes hedges etc ,they don't run it long enough to actually get hot,i see it mostly on my tanaka petrol drill,it fouls and carries on but it does have a carb from a ms260 on it:hmm3grin2orange:

Id hedge a bet that you know how to tune a saw or 3, and on top of filter/fuel maintainence

 

[jwp]

I like this discussion on mix. Tell me what you guys know about the 100:1 mix. I have seen oils that say that you can mix at 100:1. I don't think that I want to go this low. But a 100:1 oil used at a 50:1 mix should be sweet.

I also wonder just how accurate a 50:1 mix has to be. I know that I don't get out a measuring cup for my gas so I could be a few ounces one way or the other. I usually shoot for a 50:1 mix or try to make sure that I have a little more oil than needed in the mix.

Off on another tangent. Evenrude makes an Etec outboard engine that can idle with no oil for 30 hours. I guess that the materials used in engines make quite a difference when it comes to lubrication.

 

[Philip Wheelock]

...Operating temperature has a huge impact on air/fuel mixtures...

Makes sense to me. Will keep that in mind. Thanks.

 

[splitpost]

Id hedge a bet that you know how to tune a saw or 3, and on top of filter/fuel maintainence

I think so

One test done in birtbike many moon's ago b4 the 4t take over not that it's a take over when one need's 450cc of 4t to smoke 250cc of 2t,... It was a new CR125 on a dyno run at 40:1 well it lost something like 3hp after less than 6hr but they did say that was normal looking for more power running 40:1., and from there it's break out the spanners and get to work.....I guess thats ok if your last name is Reed or Bubba and you can ride like them and dont have to pay for something silly like that....myself I think bike's and saw's only have one thing in common and that's the mix...

that's probly why when I had my CR500 it called for 33:1 or there abouts ,but we are talking highend dirtbikes.......oh I miss that bike

 

[Philbert]

This continues to be an interesting discussion. I wonder how the risk of damage from temperature swings, etc.varies with guys who tune their saws for higher performance versus 'stock'. In other words, do stock specs provide some 'safety slop' for users who do not adjust their saws on a frequent or on-going basis.

Philbert

 

[boxygen]

the study I read about 2 stroke motorcycles flat out said more oil will permit an engine to make more horsepower. If more fuel wasn't delivered at the same time the power output would drop instead of go up. This was all dyno run testing. Main jets had to be enlarged with every step up in the fuel/oil ratio to maintain power. They were measure peak horsepower in a 250 cc 2 stroke air cooled engine. The conclusion was if you want to make peak power use lots of oil but balance it out with an increase of fuel delivered. If I remember right the difference in the test engine was something like 50/1 mix delivering 21 hp and the 16/1 delivering 22 or 23. not a huge amount but it is what it is. More lube = better heat transfer and less friction.

Guys, this is simple. Let me explain. This guy is on the right track. When I had my squish band cut, the compression is now much higher........ like a diesel engine. I now mix my fuel at 1:1 to compensate for my saw now running like a diesel engine and diesel is pretty much oil . The oil is now the fuel. Its science. Duh.

:jester::msp_rolleyes::msp_w00t:

 

[splitpost]

Guys, this is simple. Let me explain. This guy is on the right track. When I had my squish band cut, the compression is now much higher........ like a diesel engine. I now mix my fuel at 1:1 to compensate for my saw now running like a diesel engine and diesel is pretty much oil . The oil is now the fuel. Its science. Duh.

:jester::msp_rolleyes::msp_w00t:

WoW 1:1 you say.............got any vids,of course not.

 

[514mach1]

I use 38-45:1, usually 40:1 but it will vary a tiny bit depending on what's left in the oil bottle and exact size of my fuel jug, but it's always in the 38 to 45 to 1 range. I tune the carb about 1/5 of a turn leaner than 'just cleans up in the cut' in the winter. Then it's a bit rich in the summer but that's what I want in hot weather anyway. So I just leave it set at that.

 

[Naked Arborist]

Gave up reading on page 3. It was a loaded thread question from the start, NO ####! If you don't run a synthetic oil or blend of ur still living in the 80's. Nuf Said There!

Mix it at what ever you want but remember fuel COOLS pistons, tune, tune, tune...

Back to my beer
and "I have a potty mouth" :msp_scared:

 

[Red Amor]

Hey fellers
Ive an old 38 magnum a ms310 and a ms 180 a couple of trimmers a sthil and a Honda
all are run on 200 mills of two stroke oil to 10 litres unleaded fuel
does that sound about right I think thats 25 to 1 ?
any way allls well n good all run well n good yeah
I wondered about the difference between the higher octane fuel as opposed to the standard unleaded fuel
what do you think
thankyou yeah

 

[cmarti]

Two old poulans (3.4 & 3.7) tuned to Red Armor 50:1. All day cut....nothing blew up:dunno:
View attachment 299303

 

[sachsmo]

The Karters ran 16;1, my milling saws run ~30:1, never scored a piston yet, no bearing failures either.

50:1 may be fine but the tune of the carb (and no air leaks) is Paramount.

My stuff is relatively old and most called for 25:1. Yes oils have come a long way, but the bearings are really the same (or worse) than they were.

Milling will put a saw through about as much torture it will likely ever see. I have used Klotz Tecni-plate since Mobil stopped selling the 2T never seen the infamous "build-up" or sticky rings?

 

[jwp]

Since no two saws are identical, I wonder if each saw has a very precise mixture and carb adjustment at which it will produce the most horsepower.

Fuel mixtures have a different BTU rating from gasoline to diesel to fuel oil. The higher the BTU rating the more energy contained in the mix. But to get the most energy out of the fuel many things would have to be correct. Like compression and materials used in the engine. More energy means more heat and higher operating temperatures.

For the average chainsaw, I would think that most would not want to get the most power from the fuel but to get a cool well lubricated saw that has enough power to do the job. With this being the goal, many mixtures of oil and gasoline can be used. Just make sure to stay between the upper and lower limits of mix and keep sawing.

 

[Little Al]

Hey fellers
Ive an old 38 magnum a ms310 and a ms 180 a couple of trimmers a sthil and a Honda
all are run on 200 mills of two stroke oil to 10 litres unleaded fuel
does that sound about right I think thats 25 to 1 ?
any way allls well n good all run well n good yeah
I wondered about the difference between the higher octane fuel as opposed to the standard unleaded fuel
what do you think
thankyou yeah

My maths work out at 40ml`s of oil per litre for a 25/1 ratio= 400ml`s for 10Litres, your 200ml`s per 10 litres = a 50/1 ratio, 20ml`s per litre or 2%. If all is running well it`s not a problem, but just that your percived ratio is not what you thought. I use a ratio of 32/1 in all my saws as my newest year wise is 1988. Not trying to pick fault, thought I`d say in case you had problems

 

[Red Amor]

Thankyou Lil AL
Im lucky good folks take the time to help
Cheeres mate yeah
your post prompted me to check the capacity of the container I mix in and its a 6 liture plastic one with the chain oil bottle on the other end
I put 200 mil 2 stroke in the 5 litures not 10 like I first said
so thankfully I made the blue and no harm came from it yeah
another silly old codger moment
thanks again

 

[apn73]

so as long you run somewhere between 8:1 and 100:1 you should be good to go:msp_w00t: