# Problems Stihl MS261CM



## Sodbuster (Jun 14, 2021)

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.


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## EbS-P (Jun 15, 2021)

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


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## Sean McGillicuddy (Jun 15, 2021)

Try running some Seafoam to cleanup fuel lines.carbs etc ....





	

		
			
		

		
	
  It might help ... couldn't hurt ...


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## Bad LP (Jun 15, 2021)

Sounds like a dirty carb. Sea Foam is where I’d start and run a full tank thru it.


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## lsucet (Jun 15, 2021)

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.


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## Sodbuster (Jun 15, 2021)

EbS-P said:


> 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 (Jun 15, 2021)

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.


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## salecker (Jun 16, 2021)

Run 50:1 if you want...
Upping the oil ratio gives you a bigger safety margin on keeping your saw healthy and running good.


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## SpaceBus (Jun 16, 2021)

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 (Jun 16, 2021)

SpaceBus said:


> 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 (Jun 16, 2021)

EbS-P said:


> 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.


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## paulnlee (Jun 16, 2021)

Rusty18 said:


> 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


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## salecker (Jun 17, 2021)

SpaceBus said:


> 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 (Jun 17, 2021)

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.


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## SpaceBus (Jun 17, 2021)

salecker said:


> 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
> ...



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.


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## salecker (Jun 18, 2021)

SpaceBus said:


> 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"


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## SpaceBus (Jun 18, 2021)

salecker said:


> 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.
> ...


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


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## salecker (Jun 20, 2021)

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?


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## SpaceBus (Jun 20, 2021)

salecker said:


> 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?
> ...



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.


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## Nealm66 (Jun 20, 2021)

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 (Jun 20, 2021)

Nealm66 said:


> 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 (Jun 21, 2021)

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.


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## paulnlee (Jun 21, 2021)

So what about the expensive pre-mix non ethanol. Since this thread started as a 261 that's all I've used


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## JimBear (Jun 21, 2021)

paulnlee said:


> So what about the expensive pre-mix non ethanol. Since this thread started as a 261 that's all I've used


You will be fine with that stuff, you will want to check the shelf life after opening.


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## duramaxman05 (Jun 24, 2021)

salecker said:


> 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 ?
> ...


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.


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## SpaceBus (Jun 26, 2021)

Here's a thread that might be useful: https://opeforum.com/threads/interesting-find-troubleshooting-ms261-c-m-hard-start-issue.24517/


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## tadmaz (Jun 26, 2021)

I've heard about the solenoid stuff before.  I guess I will get the kit with the white solenoid and orange filter.  I crushed my index finger and I could use a little project while I heal up.


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## 3fordasho (Jun 27, 2021)

Purchased a new 661C in 2015 with an early version of mtronic with the white fuel solinoid.  Probable not even 2 hrs of use and the thing would not restart hot in short order (of course out of warranty)  I just replaced all the mtronic components with version 3 mtronic, the kit includes the improved black fuel solinoid, orange fuel filter/pickup, and new coil/control module.  Just over $100 and so far so good.  Part number for the kit is 1144 007 1801.   There is some youtube videos detailing replacement of all three items, not too difficult and took about an hour.  I did need a t-10 torx bit with the hole (tamperproof).


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## tadmaz (Jun 28, 2021)

I think you're mixing up the solenoid colors.  Black solenoid/white filter bad.  White solenoid/orange filter good.  Specifically for the MS261, no coil/control module needed.  Part# 1140 007 1802


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## 3fordasho (Jun 28, 2021)

tadmaz said:


> I think you're mixing up the solenoid colors.  Black solenoid/white filter bad.  White solenoid/orange filter good.  Specifically for the MS261, no coil/control module needed.  Part# 1140 007 1802


You are correct sir.  And now it's too late to edit.  Black solinoid= bad, white solinoid = new and improved.
white filter= first version, orange filter= better filtration.


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## tadmaz (Jul 3, 2021)

I had to convince the stihl guy at my ace hardware to order the exact part# I wanted.  Got the kit.  My MS261 was made in 02/18 and it had the black solenoid and white filter.  I was able to replace the solenoid without removing the carb or anything, just a little tricky getting the clip and small screw back in.  Runs great.  May be a while before I run the saw in hot conditions to see how it does.


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## Sodbuster (Jul 4, 2021)

Not sure if this would cause a difference, but on my MS261, there is a winter and summer orange tab under the cover, in the winter position it directs some heat from the engine to keep the carb from icing up. In the summer position that hole  is closed, simply slides in and out with a screwdriver.


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## tadmaz (Jul 4, 2021)

@Sodbuster did you check which color solenoid and fuel filter you've got?  You are the OP


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## Sodbuster (Jul 4, 2021)

Black solenoid, white filter. Mine is definitely not a version 3. It was purchased 11/2/2017


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## Woody5506 (Jul 27, 2021)

Sodbuster, I'm not a huge gear head but I have the same saw and my assumption is once you ran the thing dry from the old fuel, it becomes a bit tougher to get going again on a refill. Why this is, I do not know, but I've gotten used to it and try not to run the fuel dry for that reason. Everytime I do, it does what you described. Start up hard, then putter for a bit, give it throttle and it dies out or really bogs down. I basically let it idle for a bit and start feathering the throttle and its fine from there.


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## tadmaz (Jul 27, 2021)

Woody5506 said:


> Sodbuster, I'm not a huge gear head but I have the same saw and my assumption is once you ran the thing dry from the old fuel, it becomes a bit tougher to get going again on a refill. Why this is, I do not know, but I've gotten used to it and try not to run the fuel dry for that reason. Everytime I do, it does what you described. Start up hard, then putter for a bit, give it throttle and it dies out or really bogs down. I basically let it idle for a bit and start feathering the throttle and its fine from there.


Do you have the black solenoid?  If so, get the white one and let us know if it helps.  Black one is known to stay open (flood) when you turn the saw off.


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## Sodbuster (Jul 27, 2021)

Thanks Woody and Taz, I have the white solenoid. It sat for a year drained of fuel, after I shattered my wrist. Ran a couple of tanks of 90 octane, off road fuel and Stihl Platinum oil and some Sea-foam, and now it runs like a banshee, and starts great.


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## Sodbuster (Jul 27, 2021)

Sodbuster said:


> Thanks Woody and Taz, I have the white solenoid. It sat for a year drained of fuel, after I shattered my wrist. Ran a couple of tanks of 90 octane, off road fuel and Stihl Platinum oil and some Sea-foam, and now it runs like a banshee, and starts great.


And correction to Tadmaz, I previously quoted it was black, when it is definitely white.


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## Sodbuster (Jul 27, 2021)

SpaceBus said:


> 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.



You are correct, the more I run it the stronger it gets.  Was cutting some 16" dead Ash today, and it just keeps pulling harder and harder, throwing chips like crazy.


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## SpaceBus (Jul 28, 2021)

Sodbuster said:


> You are correct, the more I run it the stronger it gets.  Was cutting some 16" dead Ash today, and it just keeps pulling harder and harder, throwing chips like crazy.



It's a pretty slick system. Any future saw purchases will be fuel injected/auto tuned or electric.


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## Woody5506 (Jul 28, 2021)

tadmaz said:


> Do you have the black solenoid?  If so, get the white one and let us know if it helps.  Black one is known to stay open (flood) when you turn the saw off.



Mine doesn't flood. But, just like my small 211, when you run it out of gas, it just acts like it takes some coaxing to get the gas flowin'


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## tadmaz (Aug 5, 2021)

I had a large white oak fall this morning.  It was leaning 45 degrees for many years, amazing it lasted this long.  84F outside, saw died after a 1/2 tank of gas.  Got it started with full throttle start and finished what I wanted to do.  Would not normally start at all.  Too hot to cut for too long anyways.  But not very good for a pro saw with a $50 "fixed" solenoid and fuel filter.  Oh well.


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## tadmaz (Sep 2, 2021)

75F today, cut up the white oak.  2 tanks (pints) of gas.  No problems, but with that temp I never had problems with the white solenoid.


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