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

[altatim]

Not sure where things are going in the chainsaw industry but parts are where it pays to get big-brand. I have a 1960s John Deere tractor and I can still get 90% of the parts for it brand new from JD, I just hope Stihl keeps up with it down the road.

 

[huskihl]

Both of those oils are clean burning. If you have lots of carbon you have a tuning issue.

Maybe a fuel problem even. Those are two oils that I have never seen any carbon buildup in a saw

 

[bwalker]

Maybe a fuel problem even. Those are two oils that I have never seen any carbon buildup in a saw

K2 is extremely clean.
If you run 800 hot it will build ash on the piston as it has a fairly high mettalic content. If your rich/cool it will blowout the exhaust un combusted and the piston often will be bare metal.

 

[JimmyT]

Both of those oils are clean burning. If you have lots of carbon you have a tuning issue.

I really think it's an excessive lubrication issue with these 50cc saws.I'm cutting a lot of oak and hickory firewood running at 14,500 rpms. The mufflers are slobbering a bit but the saws are running like a banshee without excessive heat. I probably could cut cut back to 40 to 1
on the mix or lean up a bit and be okay.

 

[bwalker]

I really think it's an excessive lubrication issue with these 50cc saws.I'm cutting a lot of oak and hickory firewood running at 14,500 rpms. The mufflers are slobbering a bit but the saws are running like a banshee without excessive heat. I probably could cut cut back to 40 to 1
on the mix or lean up a bit and be okay.

I've ran plenty of 50cc saws at 32:1 with the above oils and they always burned clean.

 

[huskihl]

I really think it's an excessive lubrication issue with these 50cc saws.I'm cutting a lot of oak and hickory firewood running at 14,500 rpms. The mufflers are slobbering a bit but the saws are running like a banshee without excessive heat. I probably could cut cut back to 40 to 1
on the mix or lean up a bit and be okay.

It is excessive oil, but it’s excessive fuel as well. If it’s coming out the muffler it can stand to be leaned out a little bit