Stratto saw life

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No. Less pre mix moving through the motor, the less its lubricated.
Keep in mind that once pre mix enters the motor in fine droplet state the fuel changes phase and the oil is deposited on the internal parts. Less fuel passing through the motor= Less oil the motor sees.
Yes I can see your point, but I can't see how 20% less fuel/oil mix going through the crankcase when we're running around 2% oil in the fuel, (assuming 50 to 1 ratio, even if your up to 30 to 1 were not above a 4% mix) is going to be such a detrimental loss of lubrication, were talking a very small percentage of actual lubrication change from having even 30% less mix going through the crankcase......
 
No i don't think you understand how strato saws work, the fuel air charge in the crankcase has more fuel in it then a std design, since you just using fresh air to purge the exhaust mix. You have to have more fuel in the crankcase to make up for the air that's already in the cylinder. Hence the reason your not loosing mix going out out exhaust like a std cylinder. If all you changed in the system was to add more air and not compensate the engine would just run lean as heck all the time. The fuel improvement isn't from extremely lean ratios, it's from a more efficient cylinder evacuation process.
Pretty sure I understand it.
If mixed fuel purges out one exhaust, and clean air purges out another exhaust, less mix goes through the bottom end on the second one
 
Pretty sure I understand it.
If mixed fuel purges out one exhaust, and clean air purges out another exhaust, less mix goes through the bottom end on the second one
Yeah I see im not going to get anywhere with how little that means in terms of lost lubrication to the bearings. Your talking 1/5 less mix (20%) going through the crankcase. We're talking 0.004% less oil getting to the bearing at a 50 to 1 mix ratio with 20% less fuel going through the engine with a strato saw. Surprised any strato saws made it more then a few hours of use with so much less lubrication getting to the bottom ends.
 
Yeah I see im not going to get anywhere with how little that means in terms of lost lubrication to the bearings. Your talking 1/5 less mix (20%) going through the crankcase. We're talking 0.004% less oil getting to the bearing at a 50 to 1 mix ratio with 20% less fuel going through the engine with a strato saw. Surprised any strato saws made it more then a few hours of use with so much less lubrication getting to the bottom ends.
Where does the added efficiency come from in a 372 xtorq compared to a 372XP?
 
Yeah I see im not going to get anywhere with how little that means in terms of lost lubrication to the bearings. Your talking 1/5 less mix (20%) going through the crankcase. We're talking 0.004% less oil getting to the bearing at a 50 to 1 mix ratio with 20% less fuel going through the engine with a strato saw. Surprised any strato saws made it more then a few hours of use with so much less lubrication getting to the bottom ends.
Just a few posts ago you mentioned how your 8 year old 562 was down on compression. Do the math on that. How long does it take to cut a cord of firewood? 1 hour? 2 hours? 2 hours per cord times 10 cords per year is 20 hours per year. For 8 years. 160 hours and the ring was worn out lol. In another 8 years the bearings will be out of it too
 
My thinking... Strato in short pushes a small amont of unmixid air through to remove exhaust gases. Maybe that small amount of unmixed air over time results in more friction/wear. Lets just call it job security for some.:)
 
Yes I can see your point, but I can't see how 20% less fuel/oil mix going through the crankcase when we're running around 2% oil in the fuel, (assuming 50 to 1 ratio, even if your up to 30 to 1 were not above a 4% mix) is going to be such a detrimental loss of lubrication, were talking a very small percentage of actual lubrication change from having even 30% less mix going through the crankcase......
Two strokes are so marginally lubricated anyways it matters.
Then you through in a heavier piston and the higher temps and you have a recipe for increased wear.
And FWIW your 562 has very little run time on it for the rings to be worn.
 
The only strato saws I've rebuilt are MS441s which I think are considered the "high end" quality in the strato saw class.
Of the 3 I have i haven't noticed any bottom end problems? ,but the carbon buildup is atrocious I mean on par with 40 year old dino burning saws! Runs hot?
These saws were all used commercially and 2 severely worked ,probably more hours than I will ever put on them, bearings, crank,and pins looked good if not great,though maybe the big box store saws are a bad design? But the 441 doesn't seem to have the wear points described here that I've encountered.
A quality mix and muffler mod will hopefully help with future carbon buildup but it's unlikely that I'll ever use them enough to wear them out.
 
Two strokes are so marginally lubricated anyways it matters.
Then you through in a heavier piston and the higher temps and you have a recipe for increased wear.
And FWIW your 562 has very little run time on it for the rings to be worn.
Not with the crappy old filter set up sucking fines all the time. Fortunately that's been remedied with the updated filter set up. I wouldn't mind having it hooked up to see how many hours are on it. I'd like to know how you came to the conclusion that it prematurely wore out? 9 years I've owned it, for 8 of those years it did 10 cord for me, plus my dad's, and neighbors wood needs for heating, as well as what ever side work I had. I don't profess to be an arborist or logger but the saws been used plenty in its life. My neighbor that logs is lucky to get 2 years out of a saw, and thats just felling and bucking 6 to 7 hours a day and can't even call it 5 days a week since he hauls his own wood.
 
Not with the crappy old filter set up sucking fines all the time. Fortunately that's been remedied with the updated filter set up. I wouldn't mind having it hooked up to see how many hours are on it. I'd like to know how you came to the conclusion that it prematurely wore out? 9 years I've owned it, for 8 of those years it did 10 cord for me, plus my dad's, and neighbors wood needs for heating, as well as what ever side work I had. I don't profess to be an arborist or logger but the saws been used plenty in its life. My neighbor that logs is lucky to get 2 years out of a saw, and thats just felling and bucking 6 to 7 hours a day and can't even call it 5 days a week since he hauls his own wood.
10 cords a year can hardly qualify as hard use.
 
10 cords a year can hardly qualify as hard use.
10 cords for my self plus everything else I do. That saw has a hard life, it's more then earned its keep in the time I've had it. I'd still like to know how you quantify how a saws life has been spent not knowing what it's done or how it's cut? I've repeatedly said I do 10 cords for my self. You can search the forum for the countless times I've spent days in the woods cutting for others as well. At any rate I'm sure you and your buddy are the all knowing about everything. I'll no longer comment on this subject. Have a wonderful day.
 
So it is my understanding that a strato saw works by having 2 different air channels... one for fuel/air charge and the other for fresh air. The charge goes down into the crankcase and up through the transfers just like any other 2 stroke.. while the fresh air goes through the channel on the piston when they align and pushes air through to clean out the exhaust gasses. In this case, the fuel/air charge is still separated and goes into the crank so it should not be leaned out any from the fresh air charge. At least on the bottom end. I am sure there might be a small amount of residual fresh air left up top but that would have nothing to do with crankcase lube...
 
So it is my understanding that a strato saw works by having 2 different air channels... one for fuel/air charge and the other for fresh air. The charge goes down into the crankcase and up through the transfers just like any other 2 stroke.. while the fresh air goes through the channel on the piston when they align and pushes air through to clean out the exhaust gasses. In this case, the fuel/air charge is still separated and goes into the crank so it should not be leaned out any from the fresh air charge. At least on the bottom end. I am sure there might be a small amount of residual fresh air left up top but that would have nothing to do with crankcase lube...
You are not considering the fact that once pre mixed fuel enters the crank case the gas component flashes to a vapor and the oil is deposited in the crank case. Anything you do to decrease fuel consumption thus decreases the amount of oil that runs through the motor.
 
So it is my understanding that a strato saw works by having 2 different air channels... one for fuel/air charge and the other for fresh air. The charge goes down into the crankcase and up through the transfers just like any other 2 stroke.. while the fresh air goes through the channel on the piston when they align and pushes air through to clean out the exhaust gasses. In this case, the fuel/air charge is still separated and goes into the crank so it should not be leaned out any from the fresh air charge. At least on the bottom end. I am sure there might be a small amount of residual fresh air left up top but that would have nothing to do with crankcase lube...
You have come in a bit early with the facts, some haven't finished telling everyone how much they don't know
 
You have come in a bit early with the facts, some haven't finished telling everyone how much they don't know
The poster referenced does indeed understand how a strato motor scavenges. However, he doesn't understand how any reduction in fuel usage results in less lubrication going to the motor.
You have anything of substance to add?
 
The ms441s do sip fuel compared to the other 70cc saws I have, but the venturi opening timing has quite a bit of effect on mix potential.
The large carburetor with a small venturi draws a strong vacuum signal which has a higher ratio of fuel to air than normal, the ports are timed only to introduce the air of the strato port with the rich mixture of fuel.
You can try just cracking the throttle on the early 441 carb model and it will drown itself in fuel.
If a lubrication issue is a concern you could certainly time your strato ports or ,like Husqvarna's strato design drill a small bypass through the intake to dilute the air charge with mix.
 
The ms441s do sip fuel compared to the other 70cc saws I have, but the venturi opening timing has quite a bit of effect on mix potential.
The large carburetor with a small venturi draws a strong vacuum signal which has a higher ratio of fuel to air than normal, the ports are timed only to introduce the air of the strato port with the rich mixture of fuel.
You can try just cracking the throttle on the early 441 carb model and it will drown itself in fuel.
If a lubrication issue is a concern you could certainly time your strato ports or ,like Husqvarna's strato design drill a small bypass through the intake to dilute the air charge with mix.
Venturi size doesn't really matter in regards to the question at hand.
And bypass the strato ports defeats the purpose of them in the first place.
 

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