New to Me MS 261 - what to look out for?

Hi everyone! First post here. I just fell into a standard Stihl MS 261, 18 in. bar (not the Mtronic fancy pants techno-gobble one) that is replacing a Poulan Pro PP3516AVX (35 cc) 18incher that gave up the ghost on a 20 inch oak tree that blew down on me. Dang thing only has 30 psi of compression now. Won't even start.

Anyway, this is my first "professional" saw. I've been looking at videos and doing research and this seems like exactly the saw I should have gotten to begin with, had I any sense.

It is USED though, so what should I be looking for to make sure it's in tip-top shape? I cut about 1-2 cords a year, just a backyard guy, but dang it I need something reliable. And I'm hoping this is a saw I can pass down to my kids and grandkids when I'm old and rickety.

Any suggestions, tips, maintenance rituals are appreciated. I don't really know anything about saws, but I severely have a desire to learn.

Thanks Tar! How do I know when the sprocket needs changing? Is there a rule of thumb (2 cords = new sprocket)?

salecker said:

Run your mix ratio at 32:1,try to find gas without any ethanol,use Seafoam in the gas.
EPA is behind 50:1...oil is cheap parts and labor not so cheap.
If the saw was used when you bought it...you should pull the muffler to check the condition,should have been done before you bought it.... but we all learn as we buy saws.

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Wait....32:1? I always heard more was better when it came to 2 stroke engines. Am I tearing up my other 2 strokes at 50:1?

cd36 said:

Remember the richer oil:fuel ratio you run, the leaner the fuel:air ratio is, as the carb meters the fuel and oil together. So the less fuel and more oil in what it is metering means a leaner mixture overall.

In my 2 stroke engines I always run the recommended mixture, maybe erring a bit on to much oil, but don't go overboard.

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My thinking was that it makes sense to run 50:1 because more gas = more BOOM = more power vs the 40:1 or 32:1, but I just read that the extra oil helps seal the rings during that boom so you end up with more power at higher oil ratios (lower first numbers) in 2 stroke engines. I agree that oil is cheap and parts are expensive, so I might just swap everything over to 32:1 and see if it fouls any plugs. My outboard runs 50:1 now and I've erred on that one on the side of less oil, not more. I'm going to stop that right now!

The 70's is when the "more oil is better to seal the rings" test was ran. I found it here on Hearth.

Some things I'm reading about the 261 - do they have weak cranks? One guy said he got one with a bent crank and it made the cord you yank on to start it wobble.

Also, is it easy to get the muffler off? I'd like to check the piston ASAP when I get back home on Monday night to see what I'm dealing with. If it's broke, I might be looking for a step-by-step on how to rebuild your 261 :D

And another thing, has ANYONE ever broken their plastic 261 handle? I see a lot of complaints, but no horror stories (yet). If so, could you just swap the metal handle off a 026 or something?

salecker said:

Sure they work fine at 50:1
but if one thing goes bad you don't have any insurance.Fuel filter or air filter plugs and puts the saw in a lean situation you don't have any oil residue for back up.
You look at the dead saws that the consumer has and i see a lot of them.EPA fixed jets and 50:1. Scored pistons,dirty air filters or dull chains and a bone dry bottom end.
If you know how to tune your saw and know what sound it makes when it's running lean,then you probably are fine with 50:1.I know those things and will spend the extra pennies for the insurance or a proper mix.
Go to the HL Supply website.You will see that the aftermarket cylinder/piston kits they are develping for Stihl and Husky saws all have 40:1 mixtures recommended.
So go ahead and run 50:1...and keep looking at new saws so you know what to buy when it comes time.

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No need to get defensive, I was surprised at the difference in oil ratios and said as much, but I also said i was going to switch over to a more oil rich mixture. You're preaching to a convert, amigo

Trying to get the muffler off now and I got the two torx screws off but don't know what is next? Seems like nothing else is holding it on. Any tips?


EDIT: Nevermind, i figured it out. there's two covers like metal clips or somesuch over the top screws. Hold on for pics!

Time for Chainsaw porn!

Again, this is the carbureted version of the MS261, not the Mtronic version. Computers always seem to cause more trouble than they're worth after a couple of years and I didn't want something else to go wrong. I may be wrong, but I may be right. Either way I'm happy I think!

First I wanted to check to see if the spark arrester screen was plugged up. I didn't know it was in a screwed in spot on the side, so I took off the two visible bolts on the muffler.









I then tried to pull the muffler off, wiggle it off, or somehow get it to pop free since a video I looked at online said that it was just a pry-up after the bolts came out. Nothing worked. So i took off this cover. It had really neat little quarter turn screws.









Some snippit video online showed me where this screw was - and that it was connected to the spark arrester. Surprise!









And the arrester was clean as a whistle. Yay!











Having seen that, i still wanted to get that dang muffler off so i could look at the cylinder. I almost never figured it out. Then i did by looking at new OEM muffler replacements and seeing that they didn't come with those little keeper things in them. I took a tiny screwdriver and POP! Pried them both off, easy as pie.

Behind that was - you guessed it - more screws. I got those out lickety split.









With them out the muffler just fell away!








But it had this little gaskety-spacer thing on it. i'm not sure which way it's supposed to go so I made the teethy parts face the muffler.









Moving on, here's a view of inside the cylinder. Seems to be zero scoring to me. what do ya'll think?











And a view of the piston and rings. still looking good!

Next I wanted to check out the crankshaft so see if it was bent as someone said they are prone to do. I loosed these two nuts here, which are stuck to the cover so that's great. never need to chase them down! brilliant idea!









Then i thought, Oh, probably don't want it starting up in the house....so I removed the spark plug. You just shove a plug tool through the rubber cover around the plug I guess. I did and it worked fine.









It came out black, but i don't think it's corroded or fouled or anything. It wasn't goopy that's for sure!









That reminds me guys, there's a push-pull switch thing by the spark plug on the right. What's that do and when do I push/pull it?









Then I watched this part under that captive-nut cover to see if it wiggled or was off center when i pulled the string. It was dead center spinning. More good news!

Here's my finger pointing to the push pull thingy that I've never seen before.









While I had it apart I went ahead and ran my oiler to 100% max oil. I hope this is the oiler screw. it matches the description in a few other threads. Also, mine only turns about a quarter turn both ways. Is that normal?












This is the only chain I had. It's a greenie. I put it on. Is the bar and chain both needing to be green or just the chain? Can I just swap to full chisel chains and leave the same bar?

With the chain in place i went out to try her out.




She screamed! It was great. I cut through some silverleaf maple (dry) that was very fast, then through some wet red oak that was also very fast, but she bogged down some working with the stump sections. Oh well, I'm happy. It's at least 100000% faster than my poulon pro, that took over 2 hours to get through the red oak stump! The MS261 did it in about 1 minute flat, HAHA!

And the kids were all happy with the "sawdust" this thing threw out too. Not dust, really, but more like spaghetti strings of awesomeness. This made it a real pleasure to work with for all of us. Heck, we ran so much wood through it that I bent my splitter splitting up the logs haha!

Needless to say, I'm a happy boy!