proper mix

I didnt want to hijack the other thread so..we were talkn about mix..Stihl says 50:1..ive currently been running somwhere around 44:1...i hear more and more of this 32:1..for you saw builders should i be running 32:1 in a stock saw? And why? Have you seen things lock up on 50:1?..ive heard somewhere that the saw uses the oil as fuel to and oil is much higher in btus thus creating a higher power fuel...sorry for rambling but this subject has always left me wondering...i def want to get a good trouble free life outta my saws..

 

I also run 50:1 and have some of the same thoughts.I think if I was racing or had a ported saw from a builder I would be runnin richer better quality mix

 

I believe that 32:1 is the best idea for longevity. By the time that the gas/oil mix gets on top of the piston most if not all the oil is in the bottom end of the saw. I also believe that as Clemsonfor states in his post that the 50:1 spec is more of an EPA thing than anything else.

I refer to 'fuel' as gas+oil and 'gas' as the combustion component of 'fuel' which gets mixed with air and burned at combustion time.

The key is that there are two ratios at work here gas/oil and gas/air, as the amount of oil in the fuel increases the amount of gas decreases and the tune of the saw (gas/air) shifts toward a lean combustion condition because in any given unit of fuel mix there is a smaller volume of gas mixed with the oil in the fuel which translates to less gas mixed with air at combustion time, so this impacts the tune of your saw shifting it toward a 'more lean gas/air' condition at run time. Your carb needs to be adjusted to compensate for this (open the jets a little when going to 32:1 from 50:1).

In essence it is a volumetric consideration, 50:1 means that there are 50 units of gas to every 1 unit of oil; 32:1 is 32 units of gas to every 1 unit of oil in the fuel.

Now as the oil disipates in the bottom end there is much less gas (32 units compared to 50) getting mixed with air thus the gas/air mixture at combustion time becomes leaner.

 

I have always run 40:1 in everything and mynew stihl saw. I have since went to 32:1 with full syn oil as the only downside is one bad tune if you dont re tune. The carbon build up is only from dino oils. 50:1 can leave your saw pretty dry.

I would not go any leaner personally than 40:1 with full syn oil thats fine. Mastermind won't warranty his work if you run anyleaner than 32:1 maybe he changed it to 40:1? But their concensus is that the 50:1 is just epa stuff to meet the new air emissions guidelines. Think about it stihl one year recommends 40:1 then the next year its 50:1.. yet no change in oil or saw build???? Hmmm

 

KRL said what I basically meant by re finding your saw.

If your tuned for 50:1 then fueling up with 32:1 and not readjusting you can be running lean.

 

If you're on the edge of lean at 50:1 it can push it too far when you go to a richer mix. Irun 32:1 in all 2 stroke equipment I own. My oil of choice is Maxima K2

 

I run BelRay H1R. Husqvarna originally specified a castor based oil in the MX race bikes at 20:1. The factory switched that recommendation to 32:1 running full synthetic (at that time BelRay) because of excessive carbon build up in the coombustion chamber causing excessive heat. Castor based oils have a big advantage in alky fueled race saws as they are much less likely to drop out of suspension in alcohol, and carbon build up is not a problem since those saws are regularly torn down.

 

If i fill the tank in the 441c i can just take the bar off..start it let it run in the start position for 90 seconds then shut it off...that should calibrate the saw fer the richer mix correct?

 

If its auto tune I guess its just fuel and go. May take a buy to go to totally make max power. I have no idea how they do or calibrate on a drastic fuel change like that?

 

On my saws I fuel up warm up then adjust the screw for the best four stroke sound that I like.

 

Ik its not much of a change..but i recal it at 44:1 and it does just fine...

 

I was thinking you were 50:1...Yea not that big a jump. I bet it does fine just fueling and go like Dex said

 

This is what Stihl technical support told me to calibrate mtronics.
1) start in start position and leave in start position and let run for 90sec without fooling with throttle then move master control all the way to off
2) restart in run position and let run for 90sec and move master control all the wy to off
3) start and make 5 full cuts loaded and should be recalibrated

 

Don't forget to "turn yerself around"!

Where's @Mike From Maine when you need him?

 

I run Jred syn oil at about 40:1 give or take. Unless I accidentally grab the can for the auger which is 25:1! Holy mosquito smoker, batman!