Problems Stihl MS261CM

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Sodbuster

Minister of Fire
Sep 22, 2012
1,495
Michigan
Hi guys, I have a new MS261CM that I've had for a few years now. I started it when new, made a few cuts and put it away, because I wasn't ready to cut for the season. Then I fell and shattered my wrist, and a titanium plate and 12 screws later it was fixed, but cutting was out of the question. My daughters fiance drained the gas and ran it dry. Then my wife got ill, and I had to take care of her, she had multiple surgeries, and will be OK , but will have some deficits, that's life I guess.

Fast forward to today, I had two Ash trees that blew down, so I bucked them up and will split them tomorrow. My problem is starting the saw, when it is already hot. Sometimes it will start in the run position, sometimes not. It almost acted like it was running out of fuel. Once I get it running if I give it any throttle it would die out. It did this multiple times until I just let it idle then slowly squeezed the throttle, after that it ran and cut fine. For those of you running this saw is there a trick I don't know about? I need to go to the dealer tomorrow to have the new saw chain sharpened because I accidentally hit gravel with it, I can ask the mechanics, but they are rarely helpful in my past dealings. Any advice would be appreciated.
 

EbS-P

Minister of Fire
Jan 19, 2019
773
SE North Carolina
Sounds like an air / fuel mixture. Check the filter if you haven’t already. My ryobi acted the same way with the throttle. It was running rich.
For your m-tronic saw there is a reset procedure. Don’t know if it’s best to reset when the saw is hot or cold? Here is a video explaining it. Probably worth a try. But I’m no Stihl expert.
Evan
 
Try running some Seafoam to cleanup fuel lines.carbs etc ....
1623756550409.png
It might help ... couldn't hurt ...
 
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Bad LP

Minister of Fire
Nov 28, 2014
1,588
Northern Maine
Sounds like a dirty carb. Sea Foam is where I’d start and run a full tank thru it.
 
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lsucet

Minister of Fire
May 14, 2015
1,681
San Ysidro, New Mexico
From cold start let it run on high idle/chocked for over 90 seconds. It should tune itself. Blip the throttle and shut it off. It is very important to run 90/91 octane, 50:1 for good performance. If you pop the top cover,if I remember correctly there's a little slot with a cover that has two settings. One for winter and one for summer. Be sure is for summer at this time.
On hot start try first, just pull. If you have to do it more than two times, set it to high idle and pull. Once it starts, blip the throttle to idle.
 

Sodbuster

Minister of Fire
Sep 22, 2012
1,495
Michigan
Sounds like an air / fuel mixture. Check the filter if you haven’t already. My ryobi acted the same way with the throttle. It was running rich.
For your m-tronic saw there is a reset procedure. Don’t know if it’s best to reset when the saw is hot or cold? Here is a video explaining it. Probably worth a try. But I’m no Stihl expert.
Evan
Very helpful thanks I 'll try that. It's a brand new saw that's been in it's case so I think the air cleaner is OK. I run 90 octane recreational fuel with no ethanol, and Stihl Ultra high performance oil at 50:1.
 
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Rusty18

Member
Nov 3, 2018
47
Belpre oh
1 or 2 pulls with the choke on then turn the choke off whether it fired or not. Work college was gonna by one and they couldn’t get it started at the store because they choked it and pulled till it fired before turning the choke off...it never fired.
May be issues with the carb as others have stated but you might check the manual for new starting procedures.
 

salecker

Minister of Fire
Aug 22, 2010
1,433
Northern Canada
Run 50:1 if you want...
Upping the oil ratio gives you a bigger safety margin on keeping your saw healthy and running good.
 

SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
Increasing the oil also leans out the mixture which can lead to even more problems. 50:1 ratio with quality oil is plenty, and that is from the manufacturer and people that build hot saws for a living.
 
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EbS-P

Minister of Fire
Jan 19, 2019
773
SE North Carolina
Increasing the oil also leans out the mixture which can lead to even more problems. 50:1 ratio with quality oil is plenty, and that is from the manufacturer and people that build hot saws for a living.
But remember 25:1 is 4% oil 50:1 is 2% oil, a change of 2%. I just looked it up for fun, A temp change of 50F lead to a change in air density of about 9%. Nothing wrong with 50:1 or 37:1 in my opinion. More oil means just checking your spark screen more frequently to make sure it’s not plugged. An auto tune/mtronic saw should be making adjustments for some these variables to some extent anyway. ( I have no idea how they actually work).

Evan
 
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SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
But remember 25:1 is 4% oil 50:1 is 2% oil, a change of 2%. I just looked it up for fun, A temp change of 50F lead to a change in air density of about 9%. Nothing wrong with 50:1 or 37:1 in my opinion. More oil means just checking your spark screen more frequently to make sure it’s not plugged. An auto tune/mtronic saw should be making adjustments for some these variables to some extent anyway. ( I have no idea how they actually work).

Evan
Thanks for doing the math, didn't realize it was such a trivial amount. I run everything on 40:1 and tune the saws accordingly.


As far as the OP's 261, it does sound like the computer needs to learn the saw again after it sat for several months.
 

paulnlee

Feeling the Heat
Dec 2, 2018
419
Flemington, NJ
1 or 2 pulls with the choke on then turn the choke off whether it fired or not. Work college was gonna by one and they couldn’t get it started at the store because they choked it and pulled till it fired before turning the choke off...it never fired.
May be issues with the carb as others have stated but you might check the manual for new starting procedures.
Exactly what I learned to do with mine after returning to dealer because it wouldn't start. That's the key
 

salecker

Minister of Fire
Aug 22, 2010
1,433
Northern Canada
Increasing the oil also leans out the mixture which can lead to even more problems. 50:1 ratio with quality oil is plenty, and that is from the manufacturer and people that build hot saws for a living.
50:1 is a ratio designed to pass EPA limits
32:1 is recommended by experts who rebuild saws
your saw your choice
Carbs without adjustments designed to pass EPA limits
Carbs are made to be adjusted to have your saw run at it's best in the conditions of the day.
Experts that rebuild saws remove the limiters so you can keep your saw running for years by tuning it for the conditions that it is being used.
Use a mix with more oil for insurance,tune the saw for the conditions you are cutting .
Again your saw your choice
 
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tadmaz

Feeling the Heat
Dec 21, 2017
471
Erin, WI
My 2018 MS261CM hates running dry, and above 80F vapor locks easily. For a $600 pro saw these issues are a pain. If you run dry, use the start switch and experiment with throttle while starting. To help prevent vapor lock, open the gas when you turn the saw off and leave open until you want to start again.
 

SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
50:1 is a ratio designed to pass EPA limits
32:1 is recommended by experts who rebuild saws
your saw your choice
Carbs without adjustments designed to pass EPA limits
Carbs are made to be adjusted to have your saw run at it's best in the conditions of the day.
Experts that rebuild saws remove the limiters so you can keep your saw running for years by tuning it for the conditions that it is being used.
Use a mix with more oil for insurance,tune the saw for the conditions you are cutting .
Again your saw your choice
Take a gander at the OPE forum. A couple of builders torture tested some saws at crazy low oil ratios and they were fine. One even stopped telling customers to use 40:1 in his ported saws.
 

salecker

Minister of Fire
Aug 22, 2010
1,433
Northern Canada
Take a gander at the OPE forum. A couple of builders torture tested some saws at crazy low oil ratios and they were fine. One even stopped telling customers to use 40:1 in his ported saws.
And who would that be?
I go on Arborist site and OPE everyday for the last 10 years and have never heard a reputable builder stand behind oil ratios like that.
By reputable builders i mean the ones that take back any saws they work on and fix the issues for their customers no questions asked.
Top of that list would have a fellow by the name of Mastermind,or Tree monkey.
So provide some names please.
Don't just say stuff like" a MS150 is a clamshell saw"
 

SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
And who would that be?
I go on Arborist site and OPE everyday for the last 10 years and have never heard a reputable builder stand behind oil ratios like that.
By reputable builders i mean the ones that take back any saws they work on and fix the issues for their customers no questions asked.
Top of that list would have a fellow by the name of Mastermind,or Tree monkey.
So provide some names please.
Don't just say stuff like" a MS150 is a clamshell saw"
Mastermind said himself that he does not put 40:1 stickers on his saws anymore, have fun with that knowledge. I only listen to Huskihl and Mastermind myself, everything else is just noise.


I see you are still stuck on saw details I don't care about.

The exact comment LINK
 

salecker

Minister of Fire
Aug 22, 2010
1,433
Northern Canada
Yes he said he doesn't put the 40:1 stickers on his saws anymore!
But ill bet you he still runs all his stuff at 32:1,and i'll bet that not many of his customers will take a saw that he has worked on and run it at anything less than 50:1 regardless of the oil type.A $1000.00 plus investment in a quality tool will help you think about how to look after it.
And i also said it was your saw and you could do what you want.
How's the ported 346 of yours running?
The details i care about are when somebody keeps repeating bad information when it is totally false.
Have fun with that knowledge??
Is it a competition?
 

SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
Yes he said he doesn't put the 40:1 stickers on his saws anymore!
But ill bet you he still runs all his stuff at 32:1,and i'll bet that not many of his customers will take a saw that he has worked on and run it at anything less than 50:1 regardless of the oil type.A $1000.00 plus investment in a quality tool will help you think about how to look after it.
And i also said it was your saw and you could do what you want.
How's the ported 346 of yours running?
The details i care about are when somebody keeps repeating bad information when it is totally false.
Have fun with that knowledge??
Is it a competition?
Mastermind says in the thread 50:1 is fine for most people, I don't know what misinformation you are talking about. Manufacturers say to run 50:1 as well, are they spreading misinformation? I personally run between 32:1 and 40:1, but I'm milling with a 395xp, most people are not milling nor do they have ported saws.
 

Nealm66

Minister of Fire
Sep 25, 2020
954
Western Washington
I run everything, stock or modified, at factory recommended . Everyone else I know in the industry runs the same. No issues so far. Been that way long before there was epa regulations. Only problems I’ve ever seen running too rich of a mix is some carbon build up on the top of the piston which does cause a problem after time. I think it lowers the octane and lessens power as well. To each his own though. Internet is full of crazy stuff lol.
 
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SpaceBus

Minister of Fire
Nov 18, 2018
5,917
Downeast Maine
I run everything, stock or modified, at factory recommended . Everyone else I know in the industry runs the same. No issues so far. Been that way long before there was epa regulations. Only problems I’ve ever seen running too rich of a mix is some carbon build up on the top of the piston which does cause a problem after time. I think it lowers the octane and lessens power as well. To each his own though. Internet is full of crazy stuff lol.
Indeed, loggers and arborists all over this world run pro saws at 50:1 all day every day.
 
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salecker

Minister of Fire
Aug 22, 2010
1,433
Northern Canada
Yup and loggers and arborists all over the world don't run 50:1 as well because they belive a lttle more oil is cheap insurance.
I have said it before run your saw the way you want.
I will run 32:1 in all my mix engins
You quote Mastermind saying 50:1 is ok for most people...not all people i guess there is a line to cross ?
I hate when misinformation is puked out on the internet,then the misinformation is look at as gospel.
As for misinformation you were confident of the misinformation you were spreading .Then when proven wrong you just blamed it on the internet. :rolleyes:
 
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duramaxman05

Minister of Fire
Aug 17, 2014
517
Perryville, Mo
Yup and loggers and arborists all over the world don't run 50:1 as well because they belive a lttle more oil is cheap insurance.
I have said it before run your saw the way you want.
I will run 32:1 in all my mix engins
You quote Mastermind saying 50:1 is ok for most people...not all people i guess there is a line to cross ?
I hate when misinformation is puked out on the internet,then the misinformation is look at as gospel.
As for misinformation you were confident of the misinformation you were spreading .Then when proven wrong you just blamed it on the internet. :rolleyes:
My father in law has been logging for over 30yrs. He has always ran his saws at 50:1. Never had a saw blow up due to oil mixture. He had a dolmar 7900 give up due to bad gas but not oil. The key is using a good quality oil and keeping the saw in tune. There is a reason that he has a jonsered 2172 that is 3yrs old and still cutting with no engine repairs.