Stihl Mtronic Carb Calibration

[CanisiusHist]

Looking through the product manual for the Stihl MS400CM, it outlines a carb calibration process. Having just acquired a used Stihl M400CM via private sale, I'm curious if I should go through the calibration process, or just run the saw and let it 're-learn' as it is used. When would I want to run through the calibration process if not now?

 

[Ridgehiker]

does it run good now? if so I wouldnt worry about it, I have no experience with stihl's Mtronic, but my huskys with autotune ocassionally need a reset when there is a big change in altitude

 

[CanisiusHist]

does it run good now? if so I wouldnt worry about it, I have no experience with stihl's Mtronic, but my huskys with autotune ocassionally need a reset when there is a big change in altitude

Starts up first pull when cold. I haven't had a chance to put it in wood yet. Held at full throttle it sounded like the RPMs weren't steady but that could just be working through the gas in the fuel line from the previous owner. With this being my first saw with the Mtronic setup I figured I'd seek the experience of the collective.

 

[alexcagle]

Not good to WOT it when it's not under a load for more than a couple seconds. READ THE OPERATORS MANUAL. They are near free at dealers....
The saw may limit its own RPM automatically when not under a load via spark, which makes it sound like it's missing to your ear.
Cutoff saws do this to prevent overspeed of the blade, but it may be implemented on chainsaws that are M-tronic too.

 

[CanisiusHist]

Not good to WOT it when it's not under a load for more than a couple seconds. READ THE OPERATORS MANUAL.

I have read the operator's manual. That's where I read through the Mtronic calibration process, which includes "depressing and holding down the throttle trigger for at least 30 seconds". The service manual, courtesy of Ray Benson states the same.

 

[bwalker]

Not good to WOT it when it's not under a load for more than a couple seconds. READ THE OPERATORS MANUAL. They are near free at dealers....
The saw may limit its own RPM automatically when not under a load via spark, which makes it sound like it's missing to your ear.
Cutoff saws do this to prevent overspeed of the blade, but it may be implemented on chainsaws that are M-tronic too.

Yet the procedure for a reset requires such. With a bar and chain on it does have a load, albeit a light one.

 

[bwalker]

Looking through the product manual for the Stihl MS400CM, it outlines a carb calibration process. Having just acquired a used Stihl M400CM via private sale, I'm curious if I should go through the calibration process, or just run the saw and let it 're-learn' as it is used. When would I want to run through the calibration process if not now?

If it runs right I would not recalibrate. I think guys go overboard with resetting these things.

 

[cscltd]

You have to put it in reset mode before using full throttle, which limits it over reving for too long. Just holding throttle open does nothing to reset it.
Have to start which triangle position and let it run like that for 30 sec (use timer-don’t guess) then hold throttle open and will hear saw change rpm up and down. When you hear it go to high speed maybe after 20 sec. Let go of throttle. Shut off and restart and it’s reset.
But if running fine as stated before, just use it, it will self adjust

 

[Jza]

Like everyone has said , unless it's playing up then do a reset . Other wise it's business as usual

 

[stihltech]

Don't reset yet. Put it in the wood with a sharp chain. A lot of reset is done while under load in the wood. And it will continue to do this.
Reset is only needed when replacing a m tronic component or the guys that change large elevations. Most other cutters do not require it.