Stihl MS 261C muffler mod - results

[KWood255]

I have a Stihl MS 261C which seemed a struggle as soon as the chain became even slightly dull. When compared to my 365xp Husq, it was lazy unless the chain was perfect. After researching modifications on this site, I opened up the muffler with 3 small louvers, then reset the M-tronic. The performance improvement is incredible. It will now outperform the Husky all day.

Life expectancy of the saw may suffer a bit, but to me its a worthy trade. Ear protection is a must!

[axeman2021]

Could you take a few pictures to show us just what you did to it.

[Joe Perkins]

waiting for the picture

[KWood255]

I found this method from a different thread on this site a while ago. Results are significant. 

 

[PoginyHill]

then reset the M-tronic.

How is the M-tronic re-set?

[KWood255]

Set the starting/shut-off lever all the way down. Start the saw (as if it were in full choke mode) and leave it idle for 60-90 seconds without touching the throttle. Shut it off, the restart. Done. 

[Old saw fixer]

    The reset for M-Tronic depends on the generation of the system.  M3.0 is the current model and resets with a different procedure than KWood255 describes.  Reset for M3.0 is as follows:  With warmed up saw, apply chain brake set control in cold start and start saw without touching trigger. Allow to idle 30 to 60 seconds then pickup saw,release chain brake and hold trigger wide open until runs normally. You will hear engine revs change until reset is complete, then it runs wide open.  Done.

[KWood255]

Good to know, thanks 

[Dave12]

I did that mod on a MS260 that I owned previously.  It really woke that saw up.  I'd reach for it over the 341 or 361 that I owned at the time.  I now have a 261c and I agree with you.  It doesn't seem to have the same grunt that the modded 260 had.  I'm hesitant to mod the muffler on it because it's still under warranty.

[axeman2021]

Sthil has a C261C that does not have the Tronic adjust carb, then they have the C261CM that has the Tronic adjust carb.
The OP posted his was a C261C was this a missed print item?

[PoginyHill]

   The reset for M-Tronic depends on the generation of the system.  M3.0 is the current model and resets with a different procedure than KWood255 describes.  Reset for M3.0 is as follows:  With warmed up saw, apply chain brake set control in cold start and start saw without touching trigger. Allow to idle 30 to 60 seconds then pickup saw,release chain brake and hold trigger wide open until runs normally. You will hear engine revs change until reset is complete, then it runs wide open.  Done.

How do you determine which mod a saw is? Mine is about 4 years old. I'm guessing it is not the "current model".

[Old saw fixer]

     Look at the label on the rear handle, to the extreme right side look at the small print.  If it is M3.0 you will see it printed there.

 

[axeman2021]

If you have holes in the saws housing to adjust the carb. it's a CM261C that is a manual carb adjusting saw, if there is no holes to adjust the carb. it's a CM262 C-M that has the Auto Tronic carb adjusting system.