Chain saw fuel tank cleaning

Discuss non-crawler related issues here (keep it sane, please)
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Paul Buhler
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Post by Paul Buhler » Fri May 23, 2014 6:20 pm

Thanks Jim. That's the way I'm leaning. I noticed a smoother running 420 when I gave it some fresh gas recently, but I've had no problems with stabilized 87 octane in general. As for the small two stroke engines, I bought some straight gas and will make a 40:1 mix to see what will happen (unless I hear otherwise) I'm concerned about the added octane effects (91octane) on these engines. Any other thoughts?
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch

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Stan Disbrow
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Post by Stan Disbrow » Fri May 23, 2014 7:02 pm

Hi,

I run 100 octane racing fuel in all my 2 strokes for decades now. No additives, and it will store for at least two years. It evaporates but does not leave any residue, being pure gas. I don't run them out, and can start them all on one or two pulls with gas which has been in the tank over a year.

In the old tractors I run a 50/50 mix of 100 octane and regular pump gas. If I use only 100 octane I sometimes had icing issues with the updraft carbs. Running only pump fuel, I sometimes had starting and spark plug issues. The mix works well.

I can easily source the 100 no lead at a couple local gas stations. I can also get 100 Low Lead at the local airport. Some airports will fill cans, some won't.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

JimAnderson
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Fuels

Post by JimAnderson » Fri May 23, 2014 7:17 pm

Paul,
Higher octane fuel in any engine should not be a problem.As I
understand it lower octane fuel can cause detonation in high compression
engines like in a chainsaw.Unlike the spark knock in a 1974 Pinto you
really can't hear detonation in a 2stroke.Nothing I have seen has warned against too high an octane rating in any engine but rather warn against
too low an octane rating. It seems that the newer gasoline blends have
a much shorter shelf life than it used to have.
There seems to be many more blown up saws for sale on Ebay now
than there used to be.Everyone is mixing saw gas with ethanol laced fuel
and alcohol does not like to co-exist with oil.
Thanks for the link to the Arborist web site,in my bowsaw posts.
I would have thanked you there but didn't want to hog the responses.
Luck,JimAnderson

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Paul Buhler
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Post by Paul Buhler » Fri May 23, 2014 7:27 pm

Thanks Stan. That's the kind of Info I'm looking for.
Last week I was given a chipper/mulcher with an 8hp engine that had old gas the color and density of maple syrup in it. I drained the gas, added some new regular gas blended with some Sea foam, and got it running. It ran well, but wouldn't start without a whiff of ether. I changed out the gas for some high octane straight gas and it started right up, no ether needed. I let it run for a bit and then worked it until hot and the Sea Foam did its magic. The engine now starts hot or cold easily; the pure gas seems to help it start quicker - the heavy flywheel makes it pull and turn over more slowly, so it appears that the high octane volatiles ignite more readily ( that's my thinking anyway) getting that critical first pop going.
All this yanking and cleaning prompted my questions. Thanks for sharing your experience.
Last edited by Paul Buhler on Fri May 23, 2014 7:43 pm, edited 1 time in total.
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch

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Paul Buhler
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Post by Paul Buhler » Fri May 23, 2014 7:38 pm

As usual. I'm getting useful info to mull over and try. Thanks guys. I have 5 gallons of 91 octane straight gas to try in my small engines. I'll mix some for the two strokes, and see what happens. I'm going to put some in the 420 too.
It's reassuring to know that I'm not doing something too stupid; damaging an engine without asking for second opinions would not have made my day.
Other thoughts always welcome. Paul
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch

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Stan Disbrow
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Post by Stan Disbrow » Sat May 24, 2014 5:09 am

Hi,

The 100 octane is pure gasoline. It has a lower temp vapor point, which means it produces more vapor than pump gas does. That always makes starting easier.

It is the detonation of pump gas that causes the spark plug issues I was having. The lower the octane, the more likely it will detonate. The greater the amount of alcohol the more likely, too.

Alcohol requires twice the fuel mixed with air, so some carbs have too small main jets to get enough fuel mix into the air with gas mixed with even the 10% alky. Ethanol is a bit worse in this regard than Methanol. Anyway, when at full power the end result is an unwanted lean burn condition and detonation and new plug time. Also, the combustion temp climbs, and that can have worse consequences in aluminum air cooled engines.

When you use a higher octane fuel, you get a richer mix at full power. So, no tendency to detonate and combustion temps are cooler. There is a slightly greater amount of particulates in the exhaust, which is most of the reason for the cooler temps. The EPA will hate that thought.

Not to get too political here, it is the EPA and their anti-pollution mandate that caused all this to happen. The loss of anti-detonation tetraethyl lead, the adding of ethanol, the demise of the 2-stroke in many applications, etc. There is a law prohibiting the airport from selling 100 LL without a tail number. Some small airports will sell it and chalk it up to a school plane. Some won't. The EPA tries to eliminate 100 LL every year, but gets shot down (pun intended) by the FAA. If someone suffers detonation in a single engine small plane, they get to land on an interstate highway somewhere. ;)

Anyway, the last I bought 100 LL it was 4.75 a gallon and race 100 NL was 7.50 so guess which I opted for? But now the local airport is no longer run by country folks and some big corporate small airport outfit. So, I am back to using 100 NL.

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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Paul Buhler
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Post by Paul Buhler » Sat May 24, 2014 8:02 am

Sam: Thanks for the clear explanations. I have heard similar recently, but they were not as easy to understand. I've had an RS52 brush cutter for many years, and it works well for clearing heavy brush and small trees - I use a triangle blade, but... it doesn't run well when temps get into the 80s and above. The engine seems to vapor lock. Using your info I'm curious to see if the saw will run cooler with high octane gas and minimize this problem. I am surprised to hear that high octane gas runs cooler - this was counter intuitive to me, but your explanation makes sense.
Paul
UPDATE: Brush cutter likes new 91 octane gas w/o alchohol. It also likes that I decarboned the muffler and exhaust chamber. :oops:

Image :oops:
Paul Buhler
Killington, VT
420c 5 roll with 62 blade, FOPS, and Gearmatic 8a winch

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Stan Disbrow
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Post by Stan Disbrow » Sat May 31, 2014 7:27 am

Hi,

I just had to go to the gas station and get some 100 No Lead yesterday. Eight bux a gallon, since they have to have Road Tax on it. Actually, is is the same price at the local circle tracks. They don't have road tax, but pay more for it in barrels, so it evens out.

It isn't so bad as I only got five gallons, which will last me 6-8 weeks mixing it 50/50 with pump gas.

A new outfit took over running the station at the airport a couple months ago, and stopped selling 100 Low Lead to the farmers for their old tractors. It is five bux a gallon there. I will have to get a friend who has his plane on a grass strip to 'loan' me his tail number. They will pump it into cans if you have a plane on a private strip. But, you have to have a valid tail number for their new fancy computerized gas pump. ;)

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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NWJD fan
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Chainsaw fuel

Post by NWJD fan » Sun Jan 25, 2015 11:04 pm

Was in the local Stihl saw shop a few days back. I see they are selling premixed 92 octane 2 stroke gas in sealed containers quarts-gallons and 5 gallons with guaranteed shelf life of 5 years or more. One of the mechanics in the shop also said that ethanol is very hard on fuel lines and carb diaphragms and that ethanol is the number source of fuel-carburation problems they are seeing these days. Te last few years I have been mixing my fuel a gallon at a time and discarding it if I don't use it all in a month. If my saws are going to sit for more than a few days I drain them and run them dry.

oldtanker
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Re: Chainsaw fuel

Post by oldtanker » Mon Jan 26, 2015 10:52 pm

NWJD fan wrote:Was in the local Stihl saw shop a few days back. I see they are selling premixed 92 octane 2 stroke gas in sealed containers quarts-gallons and 5 gallons with guaranteed shelf life of 5 years or more. One of the mechanics in the shop also said that ethanol is very hard on fuel lines and carb diaphragms and that ethanol is the number source of fuel-carburation problems they are seeing these days. Te last few years I have been mixing my fuel a gallon at a time and discarding it if I don't use it all in a month. If my saws are going to sit for more than a few days I drain them and run them dry.

I try to stay out of most fuel discussions. Can start fights. My wife works at a place that sells and services outdoor power equipment. The brands they sell all say use non ethanol fuel. My old ford tractors have hardened valve seats from the factory. So you can run unleaded in them. Without the hardened seats it causes the valves/seats to wear faster. Lead was what lubed the valves. I've been running non ethanol gas for a few years now in all of my small engines and my gas tractors. Little more expensive for the gas but saves in repairs IMO.

Rick

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