Stihl MS261-CM 2020 4 months old scored piston???

[Stihl-Bummer]

So like the title Says I have a brand new 2020 chainsaw. I purchased Stihl 2 stroke oil. the orange bottle from the dealer. I use 93 Octane non-ethanol And I mix 2.6 ounces per 1 gallon for a 50:1 ratio. So I’ve used the saw maybe 4 to 6 times and I’ve cut down 2 white oak trees that are about 100 feet tall and 4 feet wide at the thickest part of the base. I usually keep the chainsaw in about 70 to 80% throttle and I sharpen the blade every time I’m done. I’ve used about six tanks of gas. This saw never gave me any issues at all one day I was milling a 6 foot long tree. making an 8 x 8 post. Now of course you can’t bury the chainsaw when your milling you have to dip the tip in and walk it backwards let off the gas and then go back to the top take another half inch to 1 inch of wood walk it back and repeat this process several times. So the throttle was at about 80% meaning I pulled the trigger Fully and slightly light off and heard the engine pitch reduce. And then it just puttered and stopped working???? Then there was no compression at all in the engine if I grab the starter rope the chainsaw will just fall all the way to the floor by itself? And it would leak the fuel out the front underneath the exhaust muffler? So since this $700 chainsaw was still within the one-year warranty I thought Stihl would completely fix it. Once they did their inspection they called me back about a week later and said the piston and cylinder were completely scored. They said it was most likely due to the fact that I was over speeding and that I was most likely using a dull chain. They said they would pay to completely rebuild the saw for all the parts as long as I pay a little less than 200$ for labor. I of course agreed and I’m getting my saw completely rebuilt bearings piston and cylinder. The dealer has been really helpful and working with me. But the question still remains I was following the manual doing 50 to 1 ratio not burying the saw I was sharpening the blade every time. I would use my air compressor every time and clean all the wood chips out clean the air filter I mean I was very meticulous and making sure it was well kept. What’s to say it’s not gonna happen again what do you guys think I did wrong? I honestly thought these chainsaws were very strong and capable of handling a lot of crud!? I don’t think Stihl is wrong and I’m glad they came to a compromise with me. Instead of completely blaming me. Is it possible that I was given a lemon chainsaw or is it possible that anyone can blow up a brand new Stihl? I really wish I pulled out the spark plug the day I brought it home and looked at the piston and cylinder to see if it was perfect. Maybe someone was red lining the snot out of it before they sold it to me.or it was just user error? What do you guys think? Has this happened to anyone else?

 

[kenton.a.frank]

I’ve always treated my saws and was taught with 2 stroke engines you should run full throttle only while cutting. Anything less and the mix is not accurate to what it should be abs may underlube the cylinder as well as bot push enough air across the cooling fins while cutting.


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[Stihl-Bummer]

Thank you for the knowledge. I will use full throttle from here on out. Of course after I let it warm up for 30 sec on first use. Do you think I should use their ultra synthetic oil? Or should I use 40:1 ratio? Or keep it at 50:1

 

[toadman]

100% throttle in the cut, there's no fuel system for part throttle.

 

[Stihl-Bummer]

Like I said I’ve been using the orange bottle but I know they make a silver ultra synthetic.

 

[Stihl-Bummer]

Of course I’m not completely accurate but I would put it at full throttle and then just slightly let off the trigger I just say it’s 80% whether it is or isn’t I don’t know. But I will most definitely from here on out during the cuts leave the trigger fully pressed.

 

[Crispexx]

So I’ve never milled a single log in my life so my 2 cents are worth more like a half cent, but I didn’t think a 261 was a strong enough saw for milling? I’ve always been told not to mill with anything smaller than 70cc. But again, I really know nothing on the subject.


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[Woodslasher]

I'd heed the dealers advice and always make sure your chain is sharp. That'll screw up most saws if you just "dog in" once the chain is dull rather than stop for a bit and swap out/sharpen the chain.

 

[toadman]

There's a lot of people who debate about oil on here, I have yet to burn up a saw using orange, or silver Stihl oil... When I was a teen I did a huge pile of data on temperatures on chain saws as a project for credit.
There was a lot of variables I kept track of, including chain sharpness, throttle input, and fuel/ oil type.
One thing I discovered was that use at less than full throttle the temps kept climbing, reaching 600*+ fast before I shut down the test, where they leveled off at 400*f ish under full throttle even under load.

2-stroke saws are air cooled, but in reality the majority of cooling comes from the fuel.

Part throttle does 2 things, it lessens the air flow on the outside of the cylinder from the flywheel fan (limiting cooling) and limits fuel & air flow inside the combustion chamber, limiting cooling yet again.

These things are on the limit as it is, and any reduction in these factors causes issues.
Also, on top of the cooling issue there's a lubrication issue under less than full throttle as these things are fuel lubed as well.
And carbon builds up fast under part throttle, which causes massive wear & can choke up exhaust.
add it all up, and it really only takes very little rubbing at 500* and 9k rpm for two dissimilar metals to eat each other apart.

 

[Stihl-Bummer]

You know I had the same conversation with someone about that yesterday. For example I cut down a 100 foot tall white oak tree. At the very bottom the base was about 4 1/2 feet wide and it stayed 4 feet wide for roughly 30 to 40 feet up and then got slimmer the further up you went. So when I cut down the Tree I would then proceed to cut it into logs. So from the base of the tree 3 feet to the right I would start cutting the tree that is 4 feet wide and that’s a substantial amount of time with the saw running buried into the tree cutting it into logs. Then I would move 3 feet to the right again cut it. And of course do this for the next shoot 1 to 2 hours until the entire tree is cut into logs. Milling It’s really no different. I have that 4 foot wide log that’s 6 feet long make a square in the center for however big you want the post to be usually only taking slim cuts off the side because the bigger the beam the stronger the bridge. Screw a 2 x 4 on the top. Attach the metal bracket to the blade on the chainsaw. Run the saw from the top of the 6 foot tree to the bottom only cutting about half an inch to An inch in depth. Then when you get to the bottom you walk back to the top repeat the process cut about half an inch to an inch while walking down the tree let off the trigger go back to the top and until of course you cut that side of the log. I could see if you went full vertical red line the chainsaw and expected to cut the entire depth of the log over the entire length you could most definitely destroy it but that’s not what I was doing.

 

[Stihl-Bummer]

Wow thank you guys for all your knowledge I do have another question if a tree is 4 feet wide or I should say 4 feet in thickness and I’m making logs let’s say 3 feet wide over the length of 40 feet when should I take the chain off and replace it with a sharp one how fast do Stihl chains become dull?

 

[toadman]

Really depends... hitting nails? did you nick the ground even for a second? hard wood? soft wood? how was is sharpened?

Typically I sharpen when it stops self feeding, or stops throwing decent chips, whichever comes first.
Some wood won't throw chips if it's very hard and or dry.
The number one way to ruin a good saw experience is a dull chain.

 

[MS500i R]

You can tell by the chips from the cut as well as cutting speed once you build up some experience. Dull chains will also have a tendency to pull the cut diagonally. Another factor is the tree, and whether it’s been rolled around on the ground. If a log has been rolled around a bit good chance ther is **** in the bark. The dirt will dull the chain faster.

 

[Stihl-Bummer]

Ok thank you!

 

[Stihl-Bummer]

Either way I wanted to vomit when they told me my saw was destroyed. But they are going to rebuild it all under warranty as long as I pay labor and I am glad they worked with me it’s a great dealer! Even when I thought I was doing it right I still have more to learn! Lol you do not just pick up a chainsaw and cut wood. There is a lot to it!

 

[Ittybittyfitty]

Maybe try a different oil, and run it richer than 50:1.

 

[full chizel]

Milling with a 261 @50:1 is asking for trouble.

 

[Stihl-Bummer]

Honestly since warranty is not gunna do this again I will add a tid bit more oil. I was also thinking of using the Lucas oil. As well as maybe doing a 45:1 ect ratio.

also I noticed the muffler mod on YouTube where you cut 3 slits in the exhaust to help cool it better I wonder if that will help? ‍

 

[Stihl-Bummer]

Milling with a 261 @50:1 is asking for trouble.

Your personal opinion what ratio would you do.

 

[Ittybittyfitty]

I'll name a few good oils but hopefully this won't turn into an oil pissing match. Yamaha 2R, amsoil dominator or Saber, mystic sea and snow, citgo air cooled, echo red armor or power blend are all good oils, try running 32:1 or 40:1 and you should be good from an oil perspective.