MS441 M-tronic warm start issues

[freeasaburt]

Hello,

a while back an arborist more or less gave me an MS441 C-M, I traded for 2 cases of beer . He told me he had the cylinder and piston replaced by aftermarket parts after the spark plug flew out of the oem cylinder, stripping the threads. After that it didn't make decent power and the saw lay unused in storage for a while. He later mentioned they never reset the m-tronic system though.
I'm guessing it's a Meteor cylinder btw, based on the price he mentioned.

I read up on m-tronic resetting and did so; the saw didn't seem to make a ton of power after that but it pulled the chain (25 inch bar) quite easily and the extra reach was a nice advantage by itself.

Recently it was more difficult to start though, and now the saw won't even allow me to do the 90sec reset, first it runs at quite high rms, those go down quickly though and then it dies. If I switch the throttle to run, it idles though, with no issues at all, and although it seems really weak for a 70cc, it cuts. Smokes a lot though (I run Motomix). It seems to be pig rich, I noticed at some point that the plug was wet in any case. However, pulling it over about 10 times with the plug removed doesn't remedy the situation.
I just did some cutting with it, then let it idle a few minutes more, then stopped it; after that, there's now way you can start it, not in the 'run' position, and not in the 'choke' position either.


I obviously cleaned the air filter, also I replaced the plug (tested, saw spark) and the fuel filter.

I'm now considering throwing the carb in the ultrasonic, if it's not the carb my guess is that the solenoid is the culprit.
Can you actually also throw the solenoid in the ultrasonic cleaner? Would it help, or should I just replace it if cleaning the carb doesn't help?

Thanks in advance for any replies.

 

[DND 9000]

Don't do the solenoid in the ultrasonic cleaner. Replace it with the current 0000 120 5111 green one. Highly possible that it is leaking.

 

[freeasaburt]

I read somewhere that the 441 needs the black solenoid? Or maybe they means you can't use the white one, and the info is from before the release of the green one.
Should I also replace the fuel filter to the orange one?

 

[DND 9000]

That is right. Get the green one, the old black one is nla. And yes change the fuel pickup body to the orange one.

 

[Maintenance supervisor]

So just to be clear, the saw was running poorly but it was still used with a 25" bar to cut with and now it's not working right?
Sounds like the strato port throttle linkage is out of sink with the carburetor. The M-tronic system has probably tried to compensate for the defect but since it was continued to be used with a defect it can no longer compensate.

 

[freeasaburt]

Well, poorly, that depends... It's my first 70cc saw, also it has the AM cylinder, and I basically only used it one day to cut quite large dead spruce, with a very sharp chain. It don't have a good reference point, basically; it worked kind of well, didn't bog down, but it didn't exactly amaze me as compared to my old 026.
The trees were brought down by wind and it was a bit of a mess, the extra reach of the 25" bar was a serious advantage.

The reset procedure went fine, it started cold or hot with one pull, and it cut well the whole day. Or not badly, in any case, I was under the impression that it lacked some power. The day afterwards it didn't want to start that easily anymore, and things got worse, up tot the point I couldn't do the reset procedure anymore.

Before I replace the solenoid I'm gonna check out the carb, is there anything special that I should pay attention to where it comes to the linkage?

 

[stihltech]

Be aware that the 441 has an update kit with carb and ign module. Pricey. This was the fix for a lot of issues with the earlier units. Watch for fuel leaks at the elbow on the fuel line. Pressure test the line and wiggle the tank. That is when you find it. May not leak fuel out.
Too bad the original cylinder is not available. The sparkplug thread fix was a common repair.
All that being said, get the green solenoid and see what happens.
Vacuum and pressure test are a must, as is a good visual internal inspection.

 

[oldbuzzard]

Replace the solenoid and fuel filter before you spend money on anything else - easy and relatively cheap.

 

[angelo c]

I keep a fresh "white" solenoid on standby. I've "fixed" many weird running issues on Mtrons by swapping solenoid/ffilter.
Finally had to replace a carb on a 201tcm as my first carb-not- solenoid repair. Done about 30 so far. 1:30 is a pretty good "bet"

 

[freeasaburt]

Lots of useful feedback... As usual, here

Gonna buy me a pressure/vac tester for sure, I am really close to -finally!- reassemble my 044 and (other) 026, with cleaned up cylinders, new pistons and a whole lot of other small parts to be replaced, first thing I want to/should do after reassembly is testing exaclty that.
If I find leaks, and it turns out to be the crank seals, I guess this newbie has to go further down the rabbit hole and split the case(s)...

In any case (mehe, the pun...), I need the testing kit, that much is clear.

 

[Wood Doctor]

Threads like this terrify me because two years ago I rebuilt a Stihl 441c-m with a new top end and it is running flawlessly today. It was straight gassed by the original owner. I always have to wonder, "What did I do right that allowed mine to work so well?" I used the original carb. Believe me, it was not an easy engine to rebuild.

 

[freeasaburt]

Did you use the fine mesh, orange fuel filter? Based on all the things I read online, (a rebuild with) a cleaned out or new carb, new solenoid and orange filter seem to be the key to success, quite often.