Stihl 441-CMR wasted too soon! M-tronic Disassembly????

Wesspur
Rugged made
Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
It`s not good to run 2 tanks in the part throttle range at 4000-6000 rpm. The mixture is not right there. M-Tronic needs full throttle to regulate the mixture. What you do is not good for the engine. Warm it up and use it as normal in the cut. No full throttle without load but in the cut you need it.
 
inter_e said:
SteveSr, I usually just pressure wash the lower end, then blow compressed air into it until it's dry, then blow lucas oil into lower end with compressed air until satisified that bearings are lightly wet. Then I clean up for reassembly after light, light honing of cylinder, just to get some crosshatch and then go over piston and rings with red scotch brite like Brad Ruch was talking about. Pressure tests after assembly and two tanks of gas at maybe 4000 to 6000rpm playing with light stuff. Then I will check compression and as long as I am int the zone there, I go to work. This haas been my process and it has worked great. Hopefully you'll agree that this is adequate, and if not please let me know your concerns with my process, because I am a sponge for knowledge. Thanks, Steve
Click to expand...

I think you missed my point... ANY abrasive process i.e. sanding, honing, grinding, and especially scotchbrite process WILL leave microscopic grit on/in the surface that was abraded. It is imperative to remove this by cleaning to keep it out of the rest of the engine.

I also don't think I would ever power wash a bottom end especially if it had the crank seals in place. I would be afraid of trapped water / humidity causing flash rusting. Could also destroy the plastic bearing retainers.

Lucas oil doesn't belong in a 2-stroke crankcase. If its what I am thinking of it is pretty thick. The best thing I have found to use is just flush with mix gas. When the gas evaporates you have your protective oil film ready to go.
 
SteveSr, yes I read your post wrong. I don't just set a freshly honed cylinder and scotchbrited piston and rings down on a clean bottom end, even if it is new. I repeatedly spray brakleen throughout them and then compressed air intil they are clean and then a little lube for assy. This also cleans the carbon off of the top of the piston nicely.I also don't stick my friggin pressure washer at 1500 lbs right down against every part of the lower end. but using it from about a foot away tends to clean out anything that has settled down there quite nicely without damaging anything. The compressed air comes immediately afterward to dry everything up nice and catch anything that the wash missed, which is always nothing. then I use the lucas for lube which disolves just fine in fuel. Everyone has there own way of putting there saws back together and I appreciate your advice.
 
DND 9000 said:
It`s not good to run 2 tanks in the part throttle range at 4000-6000 rpm. The mixture is not right there. M-Tronic needs full throttle to regulate the mixture. What you do is not good for the engine. Warm it up and use it as normal in the cut. No full throttle without load but in the cut you need it.
Click to expand...
Where did you hear that the M-tronic system cannot regulate its fuel/air mixture unless it's full throttle in wood. That makes no sense at all. That's like saying that everytime I set my saw down to idle on the ground for a couple minutes why I moving around or getting a new chain or anything that it is damaging my saw?
 
inter_e said:
Where did you hear that the M-tronic system cannot regulate its fuel/air mixture unless it's full throttle in wood. That makes no sense at all. That's like saying that everytime I set my saw down to idle on the ground for a couple minutes why I moving around or getting a new chain or anything that it is damaging my saw?
Click to expand...
Full throttle under load is necessary to properly calibrate the M-tronic system. After it is calibrated you can probably do what you want but chainsaws are not designed/intended for part throttle operation.
 
SteveSr said:
Full throttle under load is necessary to properly calibrate the M-tronic system. After it is calibrated you can probably do what you want but chainsaws are not designed/intended for part throttle operation.
Click to expand...
I am sorry you thought that I would not calibrate the saw in the early stages. I thought that was a given for anyone who had the M-tronic. Even though there are like three different systems that I have heard to calibrate properly. I go with the 60/60/ then five full cuts, but that's just me. Thanks for not leaving details out that you thought I would miss, especially since I am the jack ass that just ruined two pro saws with straight gas. Steve
 
SteveSr said:
Full throttle under load is necessary to properly calibrate the M-tronic system. After it is calibrated you can probably do what you want but chainsaws are not designed/intended for part throttle operation.
Click to expand...
I'm sorry but I think this is bull ****. It is like saying that my GSXR 750 is hurting when I'm not between 11K-13.5K. Yes that is the sweet spot and where I can get the most torque for bringing up the front wheel, but the bike doesn't get hurt just because I have to drive it sometimes out of the sweet spot.

The piston, rod, crank and bearings on pro saws with M-tronics all get the proper amount of fuel and oil even out of the sweet spot. Unless Stihl are complete freakin liars, which I'm on the fence about??? This of course is after calibration.
 
inter_e said:
Where did you hear that the M-tronic system cannot regulate its fuel/air mixture unless it's full throttle in wood.
Click to expand...

M-Tronic regulates the idle speed at idle. It uses 2 ways to do that. First ignition timing and 2nd with the fuel flow. This process is also used for the high speed. A high speed regulating sequence is started if the machine runs between 8000 and 12.000 rpms for a few seconds at constand speed. (a chainsaw is in that speed range in the cut). So if you run your saw in the part throttle range, like you said between 4000 and 6000 rpm, it`s not regulating the mixture. Also think, m-tronic still uses a diaphragm carb (like other saws without m-tronic) and a diaphragm carb can go lean in the part throttle range. (There are solutions depending on the carburetor to lower this effect, but it`s still there more or less. Normally these carbs can only create a good constand air/fuel mixture at idle and full throttle.) That`s why it is better to run the engine full throttle. There the mixture is regulated and right and the engine gets enough inside cooling form the incoming air/fuel mixture. That`s the main thing the inside cooling.

Also if you run your saw part throttle, the clutch engages not that thight as it should be. It can slip easier and you may not notice it and damage the clutch, that`s another point against part throttle use.
 
A carbureted(electronically controlled or not) chainsaw has no business being compared to a motorcycle. Apples and oranges, other than both burn gas oh leen.
 
DND 9000 said:
M-Tronic regulates the idle speed at idle. It uses 2 ways to do that. First ignition timing and 2nd with the fuel flow. This process is also used for the high speed. A high speed regulating sequence is started if the machine runs between 8000 and 12.000 rpms for a few seconds at constand speed. (a chainsaw is in that speed range in the cut). So if you run your saw in the part throttle range, like you said between 4000 and 6000 rpm, it`s not regulating the mixture. Also think, m-tronic still uses a diaphragm carb (like other saws without m-tronic) and a diaphragm carb can go lean in the part throttle range. (There are solutions depending on the carburetor to lower this effect, but it`s still there more or less. Normally these carbs can only create a good constand air/fuel mixture at idle and full throttle.) That`s why it is better to run the engine full throttle. There the mixture is regulated and right and the engine gets enough inside cooling form the incoming air/fuel mixture. That`s the main thing the inside cooling.

Also if you run your saw part throttle, the clutch engages not that thight as it should be. It can slip easier and you may not notice it and damage the clutch, that`s another point against part throttle use.
Click to expand...
That is a ton of awesome information and thank you for taking the time to explain it so thoroughly. I was told differently from the dealer, but he could not explain how the system worked either. I really appreciate your advice and help DND 9000. Also the information on the clutch, never heard that one before either.
 
cuinrearview said:
A carbureted(electronically controlled or not) chainsaw has no business being compared to a motorcycle. Apples and oranges, other than both burn gas oh leen.
Click to expand...
I was comparing two items with sweet spots at very high RPM's , and it was enough for me to get a very amazing explanation from DND 9000, so save it.
 
inter_e said:
That is a ton of awesome information and thank you for taking the time to explain it so thoroughly. I was told differently from the dealer, but he could not explain how the system worked either. I really appreciate your advice and help DND 9000. Also the information on the clutch, never heard that one before either.
Click to expand...

His explanation is very accurate. Most pro carbureted saw have mid range jets. It’s needed for limbing.
But any saw, trimmer or mower for that matter is meant to be run WFO.
And that includes you’re 750. Unless you’re a pickhat snowflake
So your comparison was accurate also.
 
stihl86 said:
His explanation is very accurate. Most pro carbureted saw have mid range jets. It’s needed for limbing.
But any saw, trimmer or mower for that matter is meant to be run WFO.
And that includes you’re 750. Unless you’re a pickhat snowflake
So your comparison was accurate also.
Click to expand...
Okay that **** was funny . and I definitely don't think I am a pickhat snowflake, but I have never heard of that. So if you mean some pycho that will bring up my front wheel to get cops to chase me and try to box me in so i can show them how slow they are, then yes, that's me. But I love the comparison because I love hearing 13K tearing through streets or wood. I wish I still had my stihl RPM guage for my 150TC. I don't feel as confident without it. I don't trust my ears as much as some of you since I am almost deaf now. And I really want to do the mod with the exhaust, limiters and key, since I am already having to piston and jug it because of my mistake. Thank you for backing up the info though>
 

Similar threads

julian1234
Stihl MS 441 C - M (M Tronic Version) *QUESTION*
Replies
16
Views
651
Colonel428
C
B
What Stihl for a 28 inch bar?
2 3 4
Replies
63
Views
3K
fields_mj
F
ClassicTinkerer
Stihl 025 - To Reuse the Old Cylinder or Not?
Replies
3
Views
329
ClassicTinkerer
ClassicTinkerer
Armosh
Not happy with Meteor cylinder
Replies
13
Views
690
Pioneer
Pioneer
E
MS 261 Carb version (2022) compression and cylinder marks
Replies
9
Views
2K
user 183106
U

Latest posts

Back
Top