New saws

[Franny K]

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.

OK is the math you had in mind? It looks like I should have quoted an earlier post. Post 30 "The differance between 50:1 and 32:1 is much less than a 30 degree swing in temperature."







But, we are sold a temperature compensated gallon of gasoline. The fuel will be more compact at lower temp, even the bore of the jet itself will be smaller at lower temperature, how about the viscosity of the mix of fuel and oil, even the viscosity of the air. Is there any possibility any flow is turbulent vs laminar that would put one in multiple semesters of calculus.

 

[bwalker]

In regards to the your math you need to figure the density of air at both temps. And then use that to calculate your fuel to air ratio. For the oil side you calculate the differance of the fuel side between the two oil to fuel ratios and then combine that with a standard temp to get you air to fuel ratio. You also must figure in the effect of humidity on the above. As air cools it has less humidity typicaly so it effects density by increasing it.
As for your last paragraph you are really sorting pepper from fly crap.
The bottom line is you should be adjusting your carb on a regular basis if you want your engine to run at peak performance at all times. That and obsessing about a 1% or less change I'm oil content while ignoring the greater effects caused temperature changes is foolish.
FWIW I based my comment on using a radical air density Guage to tune carbs when I was racing snowmobiles in concert with a Mikuni tuning card. @North by Northwest would know what I am talking about.

 

[lohan808]

After

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.

Had a conversation a while back with a elite certified Stihl buddy on this topic. Off the record he told me that if you do the reset procedure for the m tronics like you would for temperature, saw should be able to compensate for the 40:1 mix. I haven't had a stock saw in a few years to test this on but it does seem to work on my ported m tronics saw... That being said I don't run Stihl oil ( crap ) and wouldn't put it in a stock saw either. I haven't burned up any saw on 40:1 m tronic or manual carb. I even run 40:1 in the McCulloch saws. No problems at all.

 

[stihltech]

I love this. In the shop, saws do not blow up, score or otherwise fail from using a good 50:1 mix oil. Water in fuel is #1. Dull chain and lack of maintenance are next in line.
Continue on. I am going unicorn hunting myself.

 

[bwalker]

After

Had a conversation a while back with a elite certified Stihl buddy on this topic. Off the record he told me that if you do the reset procedure for the m tronics like you would for temperature, saw should be able to compensate for the 40:1 mix. I haven't had a stock saw in a few years to test this on but it does seem to work on my ported m tronics saw... That being said I don't run Stihl oil ( crap ) and wouldn't put it in a stock saw either. I haven't burned up any saw on 40:1 m tronic or manual carb. I even run 40:1 in the McCulloch saws. No problems at all.

You don't need to even do a reset.
And yes stihl oil is low quality.

 

[Franny K]

love this. In the shop, saws do not blow up,

This little piece of text made me think of a guy who for some reason got the nick name of Sir Revsalot.

 

[bwalker]

I love this. In the shop, saws do not blow up, score or otherwise fail from using a good 50:1 mix oil. Water in fuel is #1. Dull chain and lack of maintenance are next in line.
Continue on. I am going unicorn hunting myself.

Most saws that blow up are from air leaks IME.

 

[lone wolf]

I'm not the only one who experienced this problem with the new 201's... my buddy who's a professional hot saw builder, engineer had 2 that lasted only 3 weeks. He runs the best mix available.... ultimately he found some aftermarket adjustable carbs and integrated them into his 201's. Also canceled out the computer, installed meteor cylinder kits and did some porting... no more problems, the saws cut faster than my modified ms200t....

Try a 200T.

 

[huskihl]

I love this. In the shop, saws do not blow up, score or otherwise fail from using a good 50:1 mix oil. Water in fuel is #1. Dull chain and lack of maintenance are next in line.
Continue on. I am going unicorn hunting myself.

50:1 is plenty for the piston to prevent scoring. Even 100:1 is enough.

Added oil is for bearings that last either hundreds of hours or thousands of hours. For some, 3 hundred hours is a lifetime. For others it’s a couple months

 

[bwalker]

50:1 is plenty for the piston to prevent scoring. Even 100:1 is enough.

Added oil is for bearings that last either hundreds of hours or thousands of hours. For some, 3 hundred hours is a lifetime. For others it’s a couple months

Most dealers are seeing low hour saws. Anyone that knows much about saws doesn't take one to a dealer work repair.

 

[stihltech]

I must be the exception. I see lots of high hour saws. It's called Amish, loggers and firewood cutters.