Brand new ms661 bog (Mtronic 3.0)

LordFarkwad

Active Member
Tried er out again this morning and I think the Mtronic cal from the other day did what I needed it to; it fired right up and within 30sec or so of warming up, it would rip with a little throttle blip.

Will check back in if anything unexpected happens! Thanks allot, guys.
 

LordFarkwad

Active Member
Also, does that Schaeffer's 7k/9k stuff extend saw life potentially?

I read through the thread you posted, @hsell, and saw where it looked like he was getting better performance (at least how he measures it, with cut times) with the 50:1 mixes, if I remember correctly. I don't care about shaving <10% of time off a cut off it costs me in engine longevity, but is that the trade-off with leaner fuel-oil mixtures?
 

New2trees

Active Member
Harrumph!!

@swingdude,

During your morning Constitution, here’s something to digest.



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Could be wrong, but as a retired mechanic with a ton of racing experience this is what I would expect.

Gasoline will produce more power per ounce than oil so a leaner mix will produce quicker cut times. In addition gasoline undergoes a lot more evaporation than oil so (assuming there is enough oil to prevent friction damage at the skirt) a cooling effect will also be seen. That said that does not mean that a 40/1 mix does not extend wear it just means that the friction produced by this small amount of wear is less than the power increase seen with the extra fuel available at 50/1.

Just in case someone chimes in that the last few years F1 cars were being built to intentionally use oil to gain power....this was a different deal. It was due to fuel usage restrictions in F1 (the amount of fuel available is limited) so even though the oil (from the dry sump tank) had less power than gasoline it was still additional power that was not calculated by the FIA as fuel.

As to the OP's first post, you stated that the saw first started really lagging after it sat a month. Even ethanol free gas will loose low temp evaporative elements so if this was using the same fuel, the fuel was likely the issue. Fuel with ethanol is even worse as ethanol is hygroscopic (soaks up water) to the extent that (if my memory serves me) a cup of gas sitting in average air for 24 hrs will absorb 12-18 drops of water...whatever it is its a lot so always keep your gas tightly capped and if its a month old dump it in a piece of equipment that is less sensitive like a gas chipper and get fresh fuel for the saw.

Not sure where you live but there is a web service called puregas.org that lists the availability of ethanol free gasoline by area.....just be aware that not all areas allow the sale of ethanol free pump gas and many of the sources listed are racing and leaded gasoline...which are not what you want in a chainsaw, so just call and make sure they sell ethanol free pump gas before you waste a trip.

I have not had a chance to try it yet but Swift fuels now produces an unleaded avgas with 102 motor octane. I would expect this to be an excellent fuel for 2 strokes without the dangers (to the dummy running the saw) of running conventional LL100 leaded aviation gasoline.
 
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hseII

Well-Known Member
Could be wrong, but as a retired mechanic with a ton of racing experience this is what I would expect.

Gasoline will produce more power per ounce than oil so a leaner mix will produce quicker cut times. In addition gasoline undergoes a lot more evaporation than oil so (assuming there is enough oil to prevent friction damage at the skirt) a cooling effect will also be seen. That said that does not mean that a 40/1 mix does not extend wear it just means that the friction produced by this small amount of wear is less than the power increase seen with the extra fuel available at 50/1.

Just in case someone chimes in that the last few years F1 cars were being built to intentionally use oil to gain power....this was a different deal. It was due to fuel usage restrictions in F1 (the amount of fuel available is limited) so even though the oil (from the dry sump tank) had less power than gasoline it was still additional power that was not calculated by the FIA as fuel.
The link I shared above was one additional finding.

The most important reason more than 50:1 is for bottom end longevity.

50:1 is too lean for the cranks & bearings.

I’ve not taken this stance on my own, or from Methods related to bicycle racing, but from the experienced builders on those forums referenced above who collectively handle 100 times the amount of saws 1 individual or 1 Tree Service company maintains & repairs in 1 year.


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Barc Buster

Well-Known Member
I can remember when I first learned to run a chainsaw. I was around 10ish years old and I learned on an old Homie super xl that my dad fed a steady diet of 16:1. I've since watched the ratio change over the years, but experience like that makes it easy for me to believe the saw builders on other sites when they say 50:1 is simply too lean. I've had good results with the schaeffer's at around 40:1. I also like the Echo red armor and Dolmar makes a pretty good synthetic as well.
 

LordFarkwad

Active Member
I think I'm going to give some of the Schaeffer's 9k 2-cyc a try after I run through my last few gallons of Stihl Motomix.

32:1 or 40:1, what would y'all recommend trying out first?
 

LordFarkwad

Active Member
And also, do y'all mix a few gallons at a time, or what? After you mix it, will the oil disperse, or does it require shaking the container every time you go to top off the tank?
 

evo

Well-Known Member
And also, do y'all mix a few gallons at a time, or what? After you mix it, will the oil disperse, or does it require shaking the container every time you go to top off the tank?
I only get more than a gallon if I know I’m going to use more than a gallon in one day. That translates into almost never.
 

LordFarkwad

Active Member
Thanks, guys.

Got some Schaeffer's on the way. Going to try and mix me up some 40:1. Would anyone recommend a higher oil ratio, like 32:1?

Also, a local place 2 min from me has 89 octane ethanol-free. Is that rating too low? I know crap about these engines compared to just about any of y'all, but the stuff I usually run - Stihl Motomix - is 93 octane.
 

evo

Well-Known Member
Thanks, guys.

Got some Schaeffer's on the way. Going to try and mix me up some 40:1. Would anyone recommend a higher oil ratio, like 32:1?

Also, a local place 2 min from me has 89 octane ethanol-free. Is that rating too low? I know crap about these engines compared to just about any of y'all, but the stuff I usually run - Stihl Motomix - is 93 octane.
I burn the 89 e free. Saws run better than high octane with ethanol
 
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