Question for Stihl 261 autotronic aficionado's.

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jonsereds 621

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Having become infected by this site some years ago, I now have a good few older 50cc saws...Jonsereds 49sp's, stihl 026's etc. I now hear a lot about the 261 stihl and I may well have a used example sooner rather than later. My question is simply, what else does the autotrophic system do for me other than adjust the mixture (which I am well capable of) and automatically take off the choke ? Is it capable of adjusting ignition advance....can it shut the saw off if to lean/too hot? I ask as my purchase will likely be from a well known auction site and it will carry a risk. If autotronic does not adjust the timing, I would be happier with a conventional carb.....or am I missing something?
I have an MF tractor which utilises a computer for MANY functions including ground sensing radar and hydraulics...which is all grand..untill it isn't, then you have 3 or four tons of useless deadweight.
I like saws that still perform 20,30, 40 or more years later.
It seems that all 261's are now cm, or can a new 261 still be purchased as a conventional saw (no brain.) ?

I have a highly capable home built tractor mounted log splitter, on which I fixed a safety warning plate for those that may borrow it. It reads "Warning. This machine has no brain. Please use your own" (in German) so they always ask! So, as you can see I may be biased. (unnecessarily ?? )
 
I just got a ms261cm...obviously with the mtronic...and got it used and love it. It states it does manage the timings automatically but as far as shutting off if too lean or rich I do not believe it can do that...yet. Here is a link with a little info but not much.


https://m.stihlusa.com/products/technology/stihl-m-tronic/
 
I’m actually going to slowly get a full mtronic lineup. To compliment the standard carb lineup :). Can’t get rid of the old ones...
 
If you have never run M-tronic you are in for a nice surprise. The saw with it that impressed me most was a MS201T-C after using the standard carb 201T- it was nearly as good as a 200T :)
I am on my 2nd MS261C-M - sold my first one and missed it so much I had to get another....
 
It just adjusts the mix. That's it. It can compensate for an air leak by adjusting the mix and save a saw from damage, but if you know what to listen for when running a saw you should be able to hear a scream hopefully in time to shut it down.
 
Going against the grain here. I don’t see any real benefit to M-tronic. The cost of parts is high and it creates a difficult variable in troubleshooting. For what?
Many of the Mtron saws run great, but if yours doesn’t it will probably be an expensive headache.
I prefer the standard carbs saws. Partially because it’s what I know, partially because of hot starts and $70 solenoids.
 
It’s a nice little saw. If you over fill the oil tank you’ll never get the flippy cap closed. Also Stihl should have copied the 346 attachment string that retains the caps.
Mine is stock minus spark arrestor.
It’s 3/8 16”and wondering if it would perform better with 325. I have a new 325 20” but can’t bring myself to scratch it. It started yesterday with 5 pulls at 0 degrees F.
10 tanks thru it and no noticeable increase in hp.
 
It’s a nice little saw. If you over fill the oil tank you’ll never get the flippy cap closed. Also Stihl should have copied the 346 attachment string that retains the caps.
Mine is stock minus spark arrestor.
It’s 3/8 16”and wondering if it would perform better with 325. I have a new 325 20” but can’t bring myself to scratch it. It started yesterday with 5 pulls at 0 degrees F.
10 tanks thru it and no noticeable increase in hp.
They should have made those caps less complex for sure.
You running 40:1, it will take a while to see the gains, 50:1 they come a lot quicker.
Screen Shot 2018-09-19 at 11.22.19 PM.png
 
Ok now i need to research this MTronic thing... it must use some kind of O2 sensor? And it must have a stator on the saw for power?

It`s not that complicated as you think. It has a 2nd pair of poles on the flywheel to power the m-tronic system. Also there is no O2 sensor. It uses (1st) ignition timing and (2nd) fuel flow to regulate itself. It also watches the rpms. The only sensor is the temp sensor in the control unit.
 

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