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How the hell did I kill another Stihl?

drf255

drf255

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Did you check the piston when you received the saw? Believe it or not, compression can come up normal even in scored saws. I’ve been burned before and choose visual inspection of the piston as a better indicator of condition.

Not trying to be insulting, but do you know how to tune a saw by ear? Would be helpful to know if you had it tuned correctly or whether it was leaned out. Did you check the tach?

The good news is that pistons are cheap, even OEM. Your jug may clean up, but you’ll need to figure out what your original issue is or you’ll be back in the same boat in no time.
 
Skunkdynamite

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My gut says the guy before you ran some old stale fuel and possibly too much oil in the mix for a good long while. I'd check that clean spot for a leak from possibly a loose cylinder bolt too.
View attachment 799507
Which would explain the lean condition heat scoring and glazed ring.
I'm guessing who ever you bought that from knew something was awry, and pled ignorance. That gooey syrup fuel probably made the rings give a normal compression reading until it warmed up and got dry from heat, then it lost compression from glazed over rings.

Not to get into a fuel debate, but unless you buy from a really busy gas station, chances are their non-ethanol fuel is already starting to get stale when you buy it. Or likely doesn't have the mid-grade octane that Stihl recommends.
Really fresh premium fuel from a busy gas station, with the max 5% ethanol in it (by law), is far better for your saw's longevity.
:cool:
Edit;
Isn't it odd that there are only fines, and no larger wood chips mixed in, where it's stuck to the engine?
Thanks for the insight!
I do have a good mechanical background, but I have very little experience with 2 strokes. I have the expectation that a commercial saw or even a homeowner saw should supply me with firewood until I'm old enough for a pellet stove

The fine dust is indicative of being run with a dull chain? It had a new Bar and chain on it.... And fine dust in the nooks and crannies. Looking at the sellers ratings, they've gone downhill in the last 6 months to a year. Not completely ducking responsibility here, it I barely ran this saw.

Should I get a Meteor P&C kit for it? Seems like there's no complaints about them, I really don't trust Chinese crap. I need this to last... I just cleared my workbench!

This was supposed to be my intermediate saw, for felling and light work. I have the 390 for bucking the log truck loads and the 170 for the light work.
 
shadco

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The pre mix came 50:1, I did the math and added a little more mix (Stihl platinum mix)
I bought one of those graduated cylinders that we used to use for our dirt bikes to do the in can mix. Pumped a gallon of E-free at the gas station. Both fuels are in sealed cans since September.
I'll do a vacuum and pressure test before tear it down. At the rate I'm going I really need to do it weekly! Looks like these are easier to do than the homeowner saw is the only good thing.
We usually referred to those as ratio wrongs.

.
 
jltrent

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In about 30 minutes at the most remove the cylinder....clean it up, put a new $30 meteor piston in, pressure/vacuum test and run it another 1000 hours....from the looks of the piston the cylinder will need very little work to get ready. I would not blame the seller as new ones shyt happens......
 
Skunkdynamite

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In about 30 minutes at the most remove the cylinder....clean it up, put a new $30 meteor piston in, pressure/vacuum test and run it another 1000 hours....from the looks of the piston the cylinder will need very little work to get ready. I would not blame the seller as new ones shyt happens......
30 minutes! So I made the right choice on a pro saw
 
olyman

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man that sux..sorry for your trouble
when i went to my stihl dealer to get 2 stroke mix
i know i need 50to1 they said with the new oil additives and synthetics to use the 40 to 1 mix , in the orange bottle not the silver bottle.
ive been running the 015L i just rebuilt hard and checking for piston problems and found none.

when i get an old saw, i never start it, i always pull the muffler and the cylinder to remove all carbon..that stuff is bad news..
sometimes if the saw has been sitting for a while moisture will rust the inside.
im sure you know but when its running it actually sucks back from the muffler so any debris in there will go back into the cylinder

i went to pick up a used ms270 somethin or other for my dad about 3 months ago.. i was just pulling to feel compression the gent
figured i was having trouble cuz of my one arm situation..and said here let me give you a hand..i said no no
no need to start it please dont start it...... no worries i want you to see your gettin a good saw
grabs the saw...yanks it started, no warm up
and goes to rip on an old test tree he had there , bout 3/4 through it the stops dead
i knew exactly what happened and i explained to him why i didnt want it started

he said its only been sittin for 4 months.. couldnt get it to even turn over after that
but man was i aggravated, i left without a saw
rebuild it,,and sent the old man the bill. tell him if he don't pay it, I see you in small claims court..DA old man...
 
SS396driver

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My gut says the guy before you ran some old stale fuel and possibly too much oil in the mix for a good long while. I'd check that clean spot for a leak from possibly a loose cylinder bolt too.
View attachment 799507
Which would explain the lean condition heat scoring and glazed ring.
I'm guessing who ever you bought that from knew something was awry, and pled ignorance. That gooey syrup fuel probably made the rings give a normal compression reading until it warmed up and got dry from heat, then it lost compression from glazed over rings.

Not to get into a fuel debate, but unless you buy from a really busy gas station, chances are their non-ethanol fuel is already starting to get stale when you buy it. Or likely doesn't have the mid-grade octane that Stihl recommends.
Really fresh premium fuel from a busy gas station, with the max 5% ethanol in it (by law), is far better for your saw's longevity.
:cool:
Edit;
Isn't it odd that there are only fines, and no larger wood chips mixed in, where it's stuck to the engine?
I use non ethonal high test in all my equipment and carbed cars. But isn't the federal law 10% max?
 
Dph1256

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I use non ethonal high test in all my equipment and carbed cars. But isn't the federal law 10% max?
I believe that there is a 5% minimum in gas. They use ethanol as an oxygenate. It used to be lead but that was bad then they used mtbe but that caused cancer.
 
dynodave

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Hi :) Did you do a pressure and vacuum test when you got it?
I now see this as essential when getting a used saw with some time on it. WHY?
I never know if it got run with E-10. E-10 mix can harden the rubber crank seals. Hard seals can leak and I have gotten burned up saws (not that old) with leaky seals. Sure they will run, sure they seem to make reasonable compression. Then when used in a long heavy cut the leaking seal.... vacuum leak and poof melted piston.....
Any aged saw I get or work on for my friends now gets a vacuum/pressure check before I will use it to pull a load. Sure you can squirt some mix in the carb for an ignition test, but I'd never do a cut before a V/C test.
Just my 2 cents
 
MontanaResident

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I now see this as essential when getting a used saw with some time on it. WHY?
It is not essential! Run the saw will tell you most of what you need to know. Doing a pressure/vacuum test is not a simple thing, and is as different as it is difficult from saw to saw. A while back checking the metering set level was all the rage. Most don't even know what a metering set level was or is, but it became essential in diagnosing all chainsaw problems. Lots and lots of wannabe professional chainsaw mechanics on this forum. Wannabe is the emphasis, who really just repeat what they hear or read, with little understanding of what they are mis-propagating.
 

Okie

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Compression reading pictures on-line on a used saw is in the category of puffing. Might even be the compression from a air compressor tank instead of the saw.

Buying a used saw on-line from flea bay is also in the category of buying a pig in a poke, especially if no return time stated.

I've seen saws with good compression reading but when the muffler was removed for a visual it would be sadness.

With that much carbon I would check the spark arrestor and if no arestor found would be ???. (someone throwed it away previously due to being clogged)
I also make sure that the muffler is bolted down tight and the gasket is in place. Fine dust can be sucked into the cylinder if muffler is loose or not gasket for a good seal.

In addition to using a tach when tuning a chainsaw I've started using a infrared thermometer to make sure that the saw is not overheating when it is into a full bar cut and loaded up heavy on a long cut. This confirms that the saw is not overheating due to leaning out, cooling fins clogged or other issues. I've seen saws that were tuned too lean but it would not be noticeable when taking short fast cuts and not loading up the engine for a long full bar cut. (sometimes the saw will start smelling like a hot engine, hot plastics when it starts overheating and may even seize (piston swelled into the cylinder) when in the cut or stalling and then re-start and run ok for awhile after it cools down)
I'm checking the temp at the piston/cylinder block area and the saw should not exceed 350F and may not get over 325F. If it does get too 350F it will just be a gradual temp rise. If you see the saw get to 350F fast and headed towards 400F it is headed for self destruct. (piston swelling, etc) Take the saw out of the cut and let it run at medium throttle to cool down before killing the engine. If close to 400F and you kill the engine it will get hotter.
The Infrared thermometer are not expensive now days and this block temp testing can be done without a helper if the chain is sharp using a test log on the ground. (the saw will load itself)
 
Skunkdynamite

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Wow Okie! That is pretty thorough! Good to know! I have to commit to the vac/pressure testing first. I have a standard Vacuum pump, but I have to get something together for pressure. I need to do some searching on this topic, it's pretty clear that if I invest the time in testing that I'll save time and money. Which is why I am working on my equipment to begin with... I've been getting workable results tuning everything by ear for years, but like I mentioned I'm definitely wet behind the ears with 2 strokes... I'm not a fast learner either :dizzy:
 
Huskybill

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Proper carb adjustment. Not too lean. When your cutting are you at wide open throttle? The carbon build up suggests your not running at wot. Only because I seen guys do this before when there new at cutting. I even had a buddy that did this. I taught him to run wot when cutting.
 
1hander

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ive always tuned by ear but in the last year or two ive realized th..at i would never tune my LS3 418 stroker by ear, that would be stupid with all the time and money i have in it and it would explode.
thats why its equipped with wideband O2s, standalone ECU, dual knock sensors. and water injection. they are tools to keep it alive and healthy ..
so why would i not do that with my 2 strokes.....so not 3 days ago i ordered a tach to compliment the infrared therm i already have.. 2 strokes are highly wound little suckers , and with all the tech and cheap as it has gotten theres no excuse for me to not go a little further to make sure you have a healthy saw or saws, i always happy to learn something new or learn something from another person

the only parts i ever used on stihl saws other than stihl was meteor and never had problems with them personally
ive learned my lesson with chinese and knock off parts..
i learned it with bmw parts, nothing is as good as those OEM bmw parts, so now i just bear it and grin when its time
to buy parts for my old bimmers. its just not worth doing the job 3 to 4 times in 2 years as opposed to doing doing it once every 10 years.
if youve ever worked on a bmw, and i mean the blood and guts stuff, you know that do not want to be repeating the work again
any time soon.

i guess its true any time we buy something sight unseen we are rolling the dice, my problem is i can be a bit too trusting sometimes. usually when i buy a used saw in person, ill ask to do a vacuum test , that lets me remove the muffler, and i can in the exhaust port as well, if they dont to let me then i have to make a choice, most are not keen in letting you tear their saw apart , if i buy a saw online i assume that its gonna be a piston,cylinder, rings, crankshaft, crank bearings. seals, carb rebuild, needle bearings, the wear and tear items at a minimum ..so i have to get it cheap in that case.

i used to not run at wot either , till my dads saw dealer noticed the carbon and asked about it, i told him i use enough throttle to get the job done..he informed for limbs and such thats ok but if im in a real cut, its wot, after that the carbon build up wasnt a problem anymore.

but i understand that not every person who needs a saw want to have all these tools and go to all this trouble, they just want it to work, theres nothing wrong with that either,

out of curiousity, what is a good temp for a well adjusted carb in the cut at WOT

man im really sorry for your troubles boss
tomorrow will be a better day
youll get your saw rebuilt
and be wiser for it.

Rick
 
hseII

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IMO 40:1 is to rich. My ms290 was having problems with 44:1. I mixed up some 50:1 and now it runs perfectly.

Here on this forum, the cult like mentality is 'run it as rich as you can', is without merit.
I’ve seen saws with burned down bottom ends from running 50:1.

There’s Merit.

I personally run @ 36:1 Red Armor.

Why?

Because I’ve seen the insides after saws ran hard using each ratio & that settles it for me.


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hseII

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There are people here that run at 32:1 with zero problems.
Carbon build up from what I can gather on reading here, and advice given to me, is most likely a tuning problem.
Your probably running too rich a jet setting, and or the engine isn’t getting hot enough to burn off the oil properly.
40:1 is a great mixture that should work well.
It can be said that running rich and running a high oil content mix will give you good lubrication, but it can also lead to high carbon content. Too little oil mixture and too lean of a jet setting will burn an engine up. Tuning is everything
Bingo


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SteveSr

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30 minutes! So I made the right choice on a pro saw
Looks like the saw ran with poor quality oil to cause all of the carbon buildup.

However, your "September" fuel is WAAAAY out of date! 8-12 weeks MAX in a tightly sealed can.

If this was an Ebay purchase you have a year to go back at the seller for a "significantly not as described" complaint.
 
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