Stihl 261s Scoring the Cylinder

[trains]

Sad to say, but I think the issue is running your saws at part throttle.
saw are pretty much designed to run at full throttle.
Its not a 4 stroke that you can take it easy with and give part throttle, its a 2 stroke, so load the motor and go wide open throttle.

Re the oil ratio making the saw run leaner, for the small amount of extra oil, and the very small amount that it displaces as a %, its a minor thing, and only requires a very tiny mixture adjustment if at all, infact, you may find that you adjust the mixtures more for daily atmospheric changes than oil mixture, and the benefits of better oil film far outweigh any other perceived issue.
Yeah, I know, he is running M tronic saws, but I added that for those who run older saws with manual adjustment on the carb.

 

[JaredR]

Sad to say, but I think the issue is running your saws at part throttle.
saw are pretty much designed to run at full throttle.
Its not a 4 stroke that you can take it easy with and give part throttle, its a 2 stroke, so load the motor and go wide open throttle.

Re the oil ratio making the saw run leaner, for the small amount of extra oil, and the very small amount that it displaces as a %, its a minor thing, and only requires a very tiny mixture adjustment if at all, infact, you may find that you adjust the mixtures more for daily atmospheric changes than oil mixture, and the benefits of better oil film far outweigh any other perceived issue.
Yeah, I know, he is running M tronic saws, but I added that for those who run older saws with manual adjustment on the carb.

So chainsaw carvers use full throttle? And these saws score the cylinders with this little half throttle? Less than 5 hours of actual run time and only a 3rd of that at half throttle brushing, the rest of the time we were using it at full throttle under load. That's a faulty product design if so.

 

[trains]

So chainsaw carvers use full throttle? And these saws score the cylinders with this little half throttle? Less than 5 hours of actual run time and only a 3rd of that at half throttle brushing, the rest of the time we were using it at full throttle under load. That's a faulty product design if so.

Hey, just trying to offer some suggestions mate, you said that the word back from stihl was that running part throttle was making the m tronic burn the saw up.

not saying that it should happen, but running 2 strokes for some years now, and have come across issues with 2t bikes that were pottered around on, and not run hard, no it wasnt fouled plugs, but piston scoring, we turned up the oilers on those that were not ridden hard to fix the issue.

last carver i spoke to at the field day demo said he ran 25:1 and had them running pig rich, and still went thru saws regularly, seemed like he just accepted that carving was hard on saws.

let us know what the outcome is, be interested to know.

 

[JaredR]

Hey, just trying to offer some suggestions mate, you said that the word back from stihl was that running part throttle was making the m tronic burn the saw up.

not saying that it should happen, but running 2 strokes for some years now, and have come across issues with 2t bikes that were pottered around on, and not run hard, no it wasnt fouled plugs, but piston scoring, we turned up the oilers on those that were not ridden hard to fix the issue.

last carver i spoke to at the field day demo said he ran 25:1 and had them running pig rich, and still went thru saws regularly, seemed like he just accepted that carving was hard on saws.

let us know what the outcome is, be interested to know.

Sorry, didn't mean that to sound like I was mad at you. Just a bit frustrated with the whole thing.

 

[trains]

Sorry, didn't mean that to sound like I was mad at you. Just a bit frustrated with the whole thing.

All good, I can appreciate the frustration loosing 2 saws in quick succession.
Still interested in seeing what the word is from the shop, and your outcome.



in the meantime safe sawing, and happy milling.