New saws
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I have been running a 362cm for a couple of years. Recently woods ported and had the porter modify the computer for 40:1 mix. No problems with the mtronic. The "Cali tuned" idea may be something, if they are really doing that.
You can reset the Mtronic, same as any dealer can. But I don’t believe there’s a way to modify the computer to run at 40:1
Kevin that was what i was referring to. Guess i should have chosen different words.
How it was explained to me is it sends a lean pulse every now and then looking for an rpm change and if it isn't how expected it changes the fuel mix. So it should be able to adapt to whatever mix your run through it.
Sounds about right
link
Gone fishing
Freeware software to tweak it and a simple data interface would be fun.
I have a MS241cm, not much used but very happy with it so far, running on my usual 40:1 synthetic mix - no problems so far that I have noticed. It's just a really sweet little magnesium case saw - very handy indeed.
I have a MS241cm, not much used but very happy with it so far, running on my usual 40:1 synthetic mix - no problems so far that I have noticed. It's just a really sweet little magnesium case saw - very handy indeed.
The computer does that by itself just like it compensates for altitude or temperature.
The Mtronic tunes itself. Sure you could take some of the safety factors out of it and run it a bit leaner, but honestly I am pretty damn impressed with the tuning on my 400C the thing is bang on from 3500 feet in elevation to 8000+ and from 90+ degrees down to well below freezing.
I ran 20:1 in a gen 1 562xp and it never missed a beat. I also run 32:1 in my 400c and it runs perfect.
The differance between 50:1 and 32:1 is much less than a 30 degree swing in temperature.
I would like that patent number.. I am calling BS!
Bango Skank
ArboristSite Operative
I run 40:1 in my 241CM too, seems like a happy little saw. Besides that I have a pretty new 201TCM and a pretty beat up 441CM, and I’ve nothing bad to say about them. I’m thinking about getting a 572XP which would be an auto tune I think. I ran a friend’s 572xp a bit and it’s pretty smooth on my aching old hands.
I’m going to raise this one from the dead…
Through my research, looks like 50:1 is because the EPA regs and it might be best for me to run a 40:1 with my saws. I’m going to switch to red armor oil. Seems to be better than the stihl ultra.
Not trying to start another oil discussion.
Now my question is, can the m tronics compensate for the 40:1 mix? Any way for these to run lean and burn up the saw with a 40:1 mix if they don’t compensate? I didn’t want them to be designed for a 50:1 and then start having problems. Any feedback since people have been running the mtronics for awhile? Or better or worse with a 40:1 with a 261 cm, 400 cm or 500i?
Through my research, looks like 50:1 is because the EPA regs and it might be best for me to run a 40:1 with my saws. I’m going to switch to red armor oil. Seems to be better than the stihl ultra.
Not trying to start another oil discussion.
Now my question is, can the m tronics compensate for the 40:1 mix? Any way for these to run lean and burn up the saw with a 40:1 mix if they don’t compensate? I didn’t want them to be designed for a 50:1 and then start having problems. Any feedback since people have been running the mtronics for awhile? Or better or worse with a 40:1 with a 261 cm, 400 cm or 500i?
Been using red armor for a few years at the suggestion of a saw porter. It has worked fine in mtronic saws including 2 500is, a MM 461 and several 261s.
40:1 is a minimum, imo, for any saw. I agree...the whole 50:1 scheme is BS.
Been running 45:1 in all my mtronic saws since they were new. No issues. Been running the stihl oil for 30 years and haven't blown one up yet.
Edit:Never had to do a reset on any of the 4 mtronic saws I have.
I was reading that adding more oil without tuning your carb makes the saw run lean and can burn up your saw.
That doesn’t make sense to me as I do not understand how it works but I just wanted to make sure the mtronic can adjust for a 40:1 ratio.
Another thread was talking about how the jets on a ms 261 cm can’t handle a higher ratio of oil.
I’m not sure if the 500i can be “reset” for a different oil ratio.
I’m running 91 octane ethanol free with Stabil and a 50:1 mix of stihl ultra. I’ll probably just add a teaspoon of red armor to help with lubrication and that will keep me from wasting this gallon mix I already have. That will make it a 40:1
Once again I am not a mechanic so some of these questions might be stupid.
That doesn’t make sense to me as I do not understand how it works but I just wanted to make sure the mtronic can adjust for a 40:1 ratio.
Another thread was talking about how the jets on a ms 261 cm can’t handle a higher ratio of oil.
I’m not sure if the 500i can be “reset” for a different oil ratio.
I’m running 91 octane ethanol free with Stabil and a 50:1 mix of stihl ultra. I’ll probably just add a teaspoon of red armor to help with lubrication and that will keep me from wasting this gallon mix I already have. That will make it a 40:1
Once again I am not a mechanic so some of these questions might be stupid.
There is very little differance fuel to air ratio wise going from 50:1 to 32:1. Do the math and figure it out for yourself.
So when guys talk about their saw blowing up from an oil ratio change I call BS.
And this is another reason Autotune and Mtronic are of benefit to most guys.
40:1 Red Armor will do you fine but I wouldn’t mix the 2. Use the Ultra up in the saw first or mix it in for bar oil
Timber MacFallen
ArboristSite Operative
As you add more oil you are reducing the content of fuel. Less fuel means that when all else is unchanged it's a leaner mixture. However, small amounts of oil do not make a big impact. That said, people DO overlook the fact that gas and oil mixtures do not flow from small orifices/jets at the same rate as pure gasoline, so there's a compound effect.
40:1 isn't that big of a step from 50:1, but 32:1 is a notable leap from 50:1 and 25:1 is a big leap. A non-computerized traditional saw that isn't adjusted for an oil rich mix WILL run hotter. For those that doubt this I encourage you to take a thermal gun and measure your cylinder temperature at 50:1 and then again at 32:1 or 25:1. You will see the oil rich mix running notably hotter until you increase jetting.
Computerized saws will compensate for richer oil mixes by monitoring various datapoints against performance. However, I would not go richer than 40:1- which is plenty when a high quality oil is used on a stock saw.
Here's a little chart to give you an idea of how much oil is in one gallon of fuel at various ratios:
25:1 one gallon: 5.1 oz oil
32:1 one gallon: 4 oz oil
40:1 one gallon: 3.2 oz oil
42:1 one gallon: 3.0 oz oil
50:1 one gallon: 2.6 oz oil
60:1 one gallon: 2.1 oz oil
80:1 one gallon: 1.6 oz oil
100:1 one gallon: 1.28 oz oil
The differance between 32:1 and 50:1 is 1%.
The viscosity between the two is nil so their is no compounding effect.
As you increase oil content your rings seal better and you make more power so it will run hotter based on this, but it's a slight differance. I use laser heat guns on a regular basis at work and they are very coarse in the accuracy department.
