# Stihl MS660 Avgas 100LL



## Dave2500 (Dec 28, 2013)

Hello
Im new, i dont know if this is the right place to post,

Any way i got a new Ms660 and only ran one tank of the motomix through it (came in it)

i went to the airport and got 100 LL and i am using the stihl ultra oil,

to run 100ll do i need to do anything to the carb settings

Will it run to rich or lean if i dont do anything

Thanks 
Dave


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## mdavlee (Dec 28, 2013)

It will be rich if any thing on that fuel. Just tune it to what it was set on with regular fuel. Do you have a tach to tune with?


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## Dave2500 (Dec 28, 2013)

no i dont have a tach, if i just leave the setting stock will it be ok because i herd that they run a little lean from the factory


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## sachsmo (Dec 28, 2013)

I bought my first big saw years ago.

Soon found out there were little to no parts available for them (153 Sachs Dolmar)

I use VP 110 and Klotz tecniplate in my milling saws, a saw can see no torture greater than milling!


After milling many slabs with that old gal she still runs and mills GREAT!

People will tell you more octane does nothing but slow a saw down and waste your money?

They could be right? but not many of them have put a saw through what I have


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## sachsmo (Dec 28, 2013)

Welcome to the site Dave!


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## sachsmo (Dec 28, 2013)

The higher the octane, the more resistant to knock or pre-ignition it is.

It also burns a bit slower, I tune mine to "blubber' a bit out of the cut and clean up under load.


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## Dave2500 (Dec 28, 2013)

so should i be ok on the stock carb settings or try to change them? how much bubble is enough?


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## sachsmo (Dec 28, 2013)

Depends kinda sort of.

You should be able to hammer it full throttle out of the cut (with bar and chain on) and it should not over rev, but stumble or "blubber" a bit.

Then give her another 16th or so (turn out CCW on the H )for a milling tune.

Also use good synthetic oyl and mix at least 32:1 if you are doing sustained long cuts.

Give yourself and the saw a rest from time to time. Let the saw idle during the 'rest periods' eh?


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## Dave2500 (Dec 28, 2013)

sachsmo said:


> Depends kinda sort of.
> 
> You should be able to hammer it full throttle out of the cut (with bar and chain on) and it should not over rev, but stumble or "blubber" a bit.
> 
> ...


what is the best oil to use, i cut some big pieces and do some ripping of logs?

Thanks for the info, 

when i buy a tach should i tune it to the max rpm or like 300 under max?

Thanks 
Dave


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## sachsmo (Dec 28, 2013)

Oyl is like girls, there are so many who could choose one for you?

Just get a synthetic name brand. Yamalube 2T is about as good and cheap as you'll find and available at your nearest Yamaha dealer.

If you have a good ear you wont need a tach, a 660 should rev to 'bout 12.500-13,000 and still "stumble" a little bit, then just give her a bit more (CCW on the H )


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## mdavlee (Dec 28, 2013)

KLotz, belray, maxima, stihl HP, and many other good oils. Just pick one and go with it.


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## BobL (Dec 29, 2013)

A modern saw like a 660 will run fine with 50:1 on a mill. Extra lube just adds to the unburnt smoke suppressant gunk that further fouls the air around the operator. Modern lubes are so good at masking smoke with smoke suppressants we can get away with using more lube as we never see it but it is there.

I use 500 RPM below max to be really sure.

One of the most critical things about milling is always ensuring a sharp, well set chain. If it's on song and the log is sloped it should cut without any pressure under the saw/mills own weight.


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## big mog (Dec 29, 2013)

your wasting your money using avgas, its formulated for 4 stroke aircraft engines running at constant rpm at altitude, not for 2 stroke chainsaws, and as for all the advice about mixing oil at 32:1, 40:1 etc, the saw and modern semi or full synth oils are designed to run at 50:1 mixes, anything else will lead to your saw running lean and melting pistons eventually, the boffins that come up with the factory formulations are a lot cleverer than than you back room boffins


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## Locust Cutter (Dec 29, 2013)

big mog said:


> your wasting your money using avgas, its formulated for 4 stroke aircraft engines running at constant rpm at altitude, not for 2 stroke chainsaws, and as for all the advice about mixing oil at 32:1, 40:1 etc, the saw and modern semi or full synth oils are designed to run at 50:1 mixes, anything else will lead to your saw running lean and melting pistons eventually, the boffins that come up with the factory formulations are a lot cleverer than than you back room boffins



I'm not sure if you're being serious or sarcastic. Ether way, wow. For milling and sustained (at or near) w.o.t. periods in big logs/milling/decent load (coincidentally similar to the run regimen of a G.A. engine) AVgas works quite well as does any synthetic mix of 32:1 and above, tuned accordingly to the mix and conditions. I like AVgas in the summer for my saws as it runs cooler in 100 degree (F)+ heat, stands-up to detonation better in the heat and doesn't go bad nearly like the Crapahol blends do... Nor does it have near the water content or offensive odor. What by chance, is a "back room Boffin" anyway? Inquiring minds would like to know.
opcorn:


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## john taliaferro (Dec 30, 2013)

I wouldn't want to breathe the lead in the avgas .


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## Locust Cutter (Dec 30, 2013)

It goes well withe the leaded paint I chewed as a child... In all seriousness, it bothers me less than Ethanol fumes do. Might be from my G.A. background as there's nothing like the smells of AV oil and gas in a radial engine, while a Stearman's warming up on a Spring day... Makes me want to go flying... Sawing is the next best thing (after motorcycles and boats of course).


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## john taliaferro (Dec 31, 2013)

Ch 34 Sikorsky redial no flywheel tell you pumped oil in . It would blow smoke rings 1/8 mile at 10 degrees on a 8" straight pipe while loping like a big block . 115/ 145 octane 200 gal just to warm it up .


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## windthrown (Dec 31, 2013)

john taliaferro said:


> I wouldn't want to breathe the lead in the avgas .


 
No shyte. Lead even in small quantities leads to serious nerve damage (including brain damage). It smells good, but the good smell is what makes leaded gas so toxic. Lead tastes sweet which is why kids tend to eat lead paint and why leaded gas smelled good in the old days. Also the lead in gas will foul the bearings in the low end. These newer saws are not designed to run with any lead in the gas, nor are they designed to run on gas with octane higher than 93 (mixed with oil it drops to about 90).

Also running more oil in a 2-stroke is not a bad idea. 32:1 is used by more and more saw owners these days, especially if they are ported in any way. Mastermind now requires all his ported saws be run with at least 40:1, and recommends 32:1 after dealing with low end damage on some saws running leaner oil mixes. I run at 45:1 myself, mostly stock or muffler modded saws. I also run supreme unleaded no ethanol E0 gas in my saws, with 100% Elf synthetic oil.


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## Dave2500 (Dec 31, 2013)

i overlooked the lead part...... in the 60's gas had 4grams of lead per gallon and AVgas now has 2.12 (i think) i just never though of it because it is used in a ton of plaines, i though it would be better for the saw because i can not get any E free gas in commie NJ. any ideas, i do not cut that much wood maybe 5 gallons a year


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## Trx250r180 (Dec 31, 2013)

my saws have over 200 psi comp and work fine with pump gas ,i even mill with my saws ,and have not had any piston problems ,i do run 32 to 1 oil for extra protection


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## mdavlee (Dec 31, 2013)

I've been running 87 octane in mine most of the year. Not noticed any problems with it even in saws with 200 lbs of compression.


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## BobL (Dec 31, 2013)

. . . . . .These newer saws are not designed to run with any lead in the gas, nor are they designed to run on gas with octane higher than 93 (mixed with oil it drops to about 90).[/quote]

Which octane rating system are you referring to? The US uses AKI (Anti-Knock Index) which is about 5 points less than what the rest of the world which uses (RON) Octane ratings
Also none of the user manuals I have read mention anything about max octane rating - all they mention is minimum rating.


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## psgflier (Jan 2, 2014)

Your not going to get enough lead from using avgas to harm you, even if you used it 10 hours a day for the next 50 years. These days the only lead poisoning you have to worry about is in pill form delivered from an explosion of black or smokeless powder, and probably not much from black powder.
Most of the gas we get here in the states is crap, even before ethanol was added. In the 70s the refiners started putting ethers, ketones, and other volatiles into the gas that used to go up the stacks. This stuff flashes of pretty fast, that's why if it sits in a container for a couple of weeks, it looses its oomph(technical term) and gunks up fuel tanks and carburetors after a few months.
Ethanol mucked thinks up even more. Not only does it have less energy than gasoline, it attracts water. You might think that"s a good thing, especially if you have used gas dryer to get rid of water in your cars fuel tank, but ethanol attracts water from the air, and when it reaches saturation point, all of the water dumps out of it.
Four stroke engines, like your car, handle this for a while, although it does cause longer term damage, but two strokes bite the dust pretty fast. This has been a big problem in outboard engines, both two stroke and four stroke, and in chainsaws. Some of the saw shops and boat shops are selling special blend two stroke oil that is supposed to help, but they're all making money repairing engines.
Now, avgas is stable, it is the only fuel that has to meet the same standards by all refiners( there are only a few of them left) for stability, volatility and reid vaper pressure. I'd highly recommend using avgas to fill tanks and carbs of any equipment without a catalytic converter for storage.
As far as running equipment on avgas, four strokes, especially modern ones are going to have a shorter life as valves and rings foul up with lead, they just don't run hot enough to keep the lead in suspension and purge it out. The old 80/87 would have been ok, but 100ll has 4 times as much lead.
For chainsaws, they might foul the plug and maybe the rings eventually, but not anymore than running 32:1 or 40:1, or enriching up the carb mixture to make up for modifying the engine beyond its design limits.
If you have a saw that has a carb that can be adjusted, adjust it just the way you would for any fuel, four stroking with no load, two stroking under load.
The idea that avgas will foul the bearings is ludicrous.


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## sachsmo (Jan 2, 2014)

Have an old 153 that's been through hell millin'

It is still strong, so using good oyl at 32:1 and good gas sure is not hurting it any?


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## psgflier (Jan 2, 2014)

I watched mixes go from 16:1 to 24:1 then 32:1, 40:1 and now 50:1, on two stroke outboards with computer controls mixture varies from 50:1 at idle to 100:1 at full power.
Up to the 40:1 mixtures, the only change I know of( common fuels did get better from the early 50s to the late 50s, and that's when mixes went from 16:1 to 24:1) was in the composition of the oil. The old 16:1 and 24:1 mixes were for regular 30wgt crankcase oil, later blends were with special 2 stroke oils. About the time mixes changed from 40:1 to 50:1, modern saws with chrome and especially nickle plated cylinders came out, of course this is also the time gas turned to crap.
If you use a good oil, mix according to what the oil recommends.
That being said, I would mix 40:1 on old big Macs, Homelites, etc. with steel cylinders.
The richer the mix, the lower the octane of the fuel, and the more fouling of plugs, rings, etc.
Air cooled engines depend on vaporization of the fuel for part of the cooling, richer oil mixes(not fuel/air mixes) decrease the efficiency of this cooling.


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## BobL (Jan 2, 2014)

psgflier said:


> Air cooled engines depend on vaporization of the fuel for part of the cooling, richer oil mixes(not fuel/air mixes) decrease the efficiency of this cooling.


When I read this I realised this may not be completely clear to a newbie.
A richer fuel/air mix will also help cool the saw.



psgflier said:


> Your not going to get enough lead from using avgas to harm you, even if you used it 10 hours a day for the next 50 years. These days the only lead poisoning you have to worry about is in pill form delivered from an explosion of black or smokeless powder, and probably not much from black powder. .



I won't agree or disagree but I will do the math and let you decide
100LL Avgas contains between about 0.15 and 0.5 g/L - lets average that to ~0.3 g/L.

Let's look at this from the point of the saws exhaust gasses.
Using fuel with a lead concentration 0.3 g/L, a saw will exhaust about 15 micrograms of lead per Litre of exhaust.
The maximum EPA standard of exposure 0.15 micrograms of lead per cubic meter of air!
So the saw exhaust is 100,000 times above the EPA limit.

Now lets look at it from an aggregate or all day perspective
Let's say that the saw only burn 1L (~1 tankful) per hour, in a 10 hour day the saw will pump to about 3 g of lead.
At the start of the day there will next to no lead in the air and at the end of the day there will be 3 g of lead so the average is 1.5 g in total
On a still day the saw exhaust will form a half bubble of exhaust gas and dust around the operator.

To meet maximum EPA standards of 0.15 micrograms per cubic meter that 1.5g of lead must fully and immediately disperse into a half bubble that is 555 ft in diameter.
Of course the exhaust/lead does not instantaneously fully disperse into that half bubble but decreases with an inverse square of the distance from the source so where the saw and operator are located the air will contain much more lead in the air than the EPA limit, right up to where it comes out of the saw exhaust where it is 100,000 times above the limit. Experiments on highways in the 1970's showed than most of the lead emitted by motor vehicles was deposited as a dust within a few hundred feet of highways, although small amounts of the very fine dusts were/are blown as far way as Antarctica.
Any potential problem is compounded by the location of the exhaust exiting from most saws because during milling it deflects off the log and blows back up into the operators face.

Like I said , that is just some basic maths - you decide.

For further comments on the phasing out of lead in Avgas, and the "environmental regulation" there of it is worth having a read of the Wikipedia entry on avgas.
http://en.wikipedia.org/wiki/Avgas

BTW Just about everyone thinks that the lead from leaded gasoline, leaded paint scrapings, industrial smelting dusts etc generated during the last century has magically disappeared. It hasn't, massive amounts of lead from this use resides in the top 2-3 ft of soils especially in urban area, river and estuary bottoms and represents an awaiting problem. Every time this is disturbed lead is kicked back up into the atmosphere as dust. The lab I worked in for 30 years can even identify which country a piece of urban soil comes from by the anthropogenically deposited lead isotopes present in these soils. This lead is a serious potential future hazard because all that has to happen to mobilise this lead into our ground water is for precipitation to become more acidic - which we are also slowly doing because we keep pumping more CO2 into the air At the present rate of acidification of the atmosphere it is not clear how much time we have left before our major groundwaters are contaminated. This is a very nasty little time bomb we have left our grandkids that they will not thank us for.


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## sachsmo (Jan 3, 2014)

Dang Bob,

you take all the fun out of it gettin' all Scientific and stuff.


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## BobL (Jan 3, 2014)

sachsmo said:


> Dang Bob,
> you take all the fun out of it gettin' all Scientific and stuff.



Sorry Sach, In terms of total exposure, if anyone is an occasional chainsaw user, e.g. a couple of days a month and chooses to use Avgas on a windy day, I doubt it would add much lead to their overall intake. 10 hours a day for 50 years would be something else.


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## samdweezel05 (Jan 3, 2014)

big mog said:


> your wasting your money using avgas, its formulated for 4 stroke aircraft engines running at constant rpm at altitude, not for 2 stroke chainsaws, and as for all the advice about mixing oil at 32:1, 40:1 etc, the saw and modern semi or full synth oils are designed to run at 50:1 mixes, anything else will lead to your saw running lean and melting pistons eventually, the boffins that come up with the factory formulations are a lot cleverer than than you back room boffins



Yup 50:1 works great if your bucking 18" logs and it takes you an hour to go through a tank of gas. This bucking is what the oil guys are expecting you to do with your saw. They never intended it to be run for a full tank under load with out a single second of idle time. I can hold my 660 wide open for 12 minutes on the mill under load before it's out of gas. I would rather use an extra 20 cents worth of oil and run 32:1 on the mill and 40:1 on everything else. I also use AV fuel....for storage.


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## samdweezel05 (Jan 3, 2014)

Trx250r180 said:


> my saws have over 200 psi comp and work fine with pump gas ,i even mill with my saws ,and have not had any piston problems ,i do run 32 to 1 oil for extra protection



I hear your saws are ported by a hack.


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## Trx250r180 (Jan 3, 2014)

samdweezel05 said:


> I hear your saws are ported by a hack.



I heard the same thing too..............don't believe everything you read on the internet ..........


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## samdweezel05 (Jan 3, 2014)

Trx250r180 said:


> I heard the same thing too..............don't believe everything you read on the internet ..........



I was praying it wasn't true as he has one of mine now.


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## sachsmo (Jan 4, 2014)

Always figured an ounce o' prevention is worth a pound o' cure.

Milling with a chainsaw has got to be harder on them than almost anything else. .

Perhaps _*you *could get by with 50:1 87 octane, I for one will leave it to someone else to try. (ever try to find a P&C fer a 30+ year old Sachs Dolmar?)

Actually what I put them through I picked one up off the bag (just in case)_


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## sachsmo (Jan 4, 2014)

Why do you think the race karters ran 16:1?

It wasn't about the RPMs it was about the _duration_* they held those RPMS!*


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## mdavlee (Jan 4, 2014)

The 87 octane part isn't bad. Its the 50:1 part that scares me for running a cut that takes the whole tank of mix.


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## sachsmo (Jan 4, 2014)

Cylinder coatings are very good these days,

Bearing technology has NOT been keeping up, in fact on newer saws me thinks they are going backward?


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## sachsmo (Jan 4, 2014)

mdavlee said:


> The 87 octane part isn't bad. Its the 50:1 part that scares me for running a cut that takes the whole tank of mix.




Ain't so much the octane,

It is the e that scares me more.

Although probably not needed the higher octane does help with knock and pre- ignition.

And it keeps for a good while also.

If'n I didn't have it available right in town, I would probably not go out of me way to get it eh?


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## mdavlee (Jan 4, 2014)

I have plenty of e free and 87 is always the freshest.


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## sachsmo (Jan 4, 2014)

Good for you,

where are the pics of your slabs?


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## mdavlee (Jan 4, 2014)

sachsmo said:


> Good for you,
> 
> where are the pics of your slabs?



On the other site is most of them. They'll be more when I get more time at home.


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## sachsmo (Jan 4, 2014)

GOOD!


We can get no e stuff all around here.

89 octane e free at the co-op and a few bulk dealers.

Funny thing is, they put a big ethanol plant up ' bout 15 miles from here, the Farmers lobby for the use of ethanol, but for their equipment they demand e free?

Farmers have ALWAYS been wily mechanics (or they don't stick around long)


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## mdavlee (Jan 4, 2014)

There's more and more independent owned stations selling it. Exxon, BP, and the other chains sell 10% but our marathons are switching to e free as are a couple of oil company owned stations that do bulk fuel/hearing oil. We have 87, 89, and 93.


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## samdweezel05 (Jan 4, 2014)

sachsmo said:


> GOOD!
> 
> 
> We can get no e stuff all around here.
> ...



At the risk of sounding like a doof, making your comment sound a bit off and as a guy that works on a farm.....when was the last time you heard of them putting ethanol in diesel fuel? Also, when was the last time you saw a farmer with a piece of gas powered equipment other than maybe his pickup truck or an ATV? We go through 100,000+ gallons of diesel a year vs 2,000 gallons of gas. Ethanol is the least of our worries.


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## BobL (Jan 4, 2014)

sachsmo said:


> Always figured an ounce o' prevention is worth a pound o' cure.
> Milling with a chainsaw has got to be harder on them than almost anything else. .
> Perhaps _*you *could get by with 50:1 87 octane, I for one will leave it to someone else to try. (ever try to find a P&C fer a 30+ year old Sachs Dolmar?)
> Actually what I put them through I picked one up off the bag (just in case)_



BlueRider has been milling with 50:1 for about 20 years on an 076 using fully synthetic oil.
I use 40:1 and just remember some of the stuff I mill green is harder than dry hickory.
If I could get fully synthetic lube I would use 50:1


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## sachsmo (Jan 5, 2014)

To each his own brother.

I've had success with my methods.


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## sachsmo (Jan 5, 2014)

samdweezel05 said:


> At the risk of sounding like a doof, making your comment sound a bit off and as a guy that works on a farm.....when was the last time you heard of them putting ethanol in diesel fuel? Also, when was the last time you saw a farmer with a piece of gas powered equipment other than maybe his pickup truck or an ATV? We go through 100,000+ gallons of diesel a year vs 2,000 gallons of gas. Ethanol is the least of our worries.




Thankfully there are still a few operations around these parts that haven't gone full blown commercial,,,,,,,,,YET!

Even the big operators have quite a bit of gas powered equipment.

Just find it funny that in the middle of the corn belt, e free is pretty easy to get?


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## samdweezel05 (Jan 5, 2014)

sachsmo said:


> Thankfully there are still a few operations around these parts that haven't gone full blown commercial,,,,,,,,,YET!
> 
> Even the big operators have quite a bit of gas powered equipment.
> 
> Just find it funny that in the middle of the corn belt, e free is pretty easy to get?



This is a family owned farm (father and son) started back in 1962 that currently has 16 employees total. Not exactly commercial. We milk 1,500 cows and work 3,800 acres. Besides 2 pickups and a couple of 5hp water pumps, everything is diesel including our John Deere Gator. We can get E free all summer long and occasionally in the winter too but only in 91 octane.


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## Mad Professor (Jan 6, 2014)

john taliaferro said:


> I wouldn't want to breathe the lead in the avgas .


I be more concerned in the lead in the food from China


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## Mad Professor (Jan 6, 2014)

samdweezel05 said:


> This is a family owned farm (father and son) started back in 1962 that currently has 16 employees total. Not exactly commercial. We milk 1,500 cows and work 3,800 acres. Besides 2 pickups and a couple of 5hp water pumps, everything is diesel including our John Deere Gator. We can get E free all summer long and occasionally in the winter too but only in 91 octane.



Where in NY? Nothing E free close to the Vermont border, or southern Vermont for that fact (maybe Marinas by Champlain?).

I run 100LL in all my two strokes. Some need to be leaned out a bit some are fine as is. I use Golden Spectro at 50:1 and have so for 35 years, dirtbikes and saws, including my 066 on the mill. If you need more oil I suspect it is what you are mixing it with. No disrespect to Mastermind but don't feed your saws corn. 

I started using 100LL when they put MBTE in the fuel years before ethanol. MBTE was bad but ethanol is worse. Just cleaned the SNOT out of several carbs on 4 stroke equipment, due to corn fuel. I will run those dry from now on 100LL is too much $$$ on a large scale and the airport is not as friendly since 9/11. 

I used to be able to drive my Camaro past the hanger to the pumps, with 12:1 compression and 210 psi the motor loved that fuel. We also had another airport that had the green 115 AV gas, I could cut that 50:50 with pump gas for the car.

I am not a commercial operator and no longer sell cordwood so a little lead is not a concern for me. Having things start up when I need them is.


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## Dave2500 (Jan 7, 2014)

I would like to thank every answered, thanks again, i think ill use avgas when i dont have to cut to much, but i may go out to pa to get some E free and fill up a 100 gallon tank and use it in my lawn mowers and play toy car too,

Thanks again


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