Stihl 2-mix strato vs Husky/Poulan strato

[Old2stroke]

With the Husky/Poulan strato that has been around for a long time, the only apparent worthwhile feature is better emission control, now Stihl would like us to believe that their version of stratified charge design will be the saw of the future due to much better emission standards, higher rpm, more power and better fuel economy. Got any issues? Here are a few comparison points.
....Stihl has a lighter piston permitting higher rpm?
....With the Poulan strato, the strato air supply only gets introduced above idle, Stihl has it from idle all the way up?
...Poulan has non-adjustable strato air, the supply is linked to throttle opening, Stihl is adjustable.
...Any difference in holding a tune? The Poulan one is notorious for requiring frequent adjustment.
...How about actual cutting performance, lugging power, acceleration from idle, consistent return to idle.
...Ease of starting hot and cold.

 

[huskihl]

It’s got nothing to do with Poulan, other than they’re owned by husky.

Husky bought redmax/Zenoah for their strato technologies. The EU forced Husky to share the tech with Stihl.

The systems differ slightly, but they’re basically identical inside

With the Poulan strato, the strato air supply only gets introduced above idle, Stihl has it from idle all the way up?
...Poulan has non-adjustable strato air, the supply is linked to throttle opening, Stihl is adjustable.
...Any difference in holding a tune? The Poulan one is notorious for requiring frequent adjustment.

None of this is true. If it is, it is for the others also

 

[Franny K]

Some strato designs the air only is the top half of butterfly valve and the gas/air is the lower. Other designs have a separate butterfly valve block for air only and gas/air and the linkage for the air only does start to open after the gas/air butterfly has opened some. I only have a MS251 which is the first way and a Dolmar 6100 which is the second way. Are all Stihl products the same in this regard?

 

[Old2stroke]

It’s got nothing to do with Poulan, other than they’re owned by husky.

Husky bought redmax/Zenoah for their strato technologies. The EU forced Husky to share the tech with Stihl.

The systems differ slightly, but they’re basically identical inside




None of this is true. If it is, it is for the others also

Not sure why you had to point out the well understood background of Husky, I mention Poulan because it's the most common strato saw out there so maybe it's the one most folk are familiar with.
Agreed that the end result in the combustion chamber is about the same for all strato engines but the Stihl 2-mix has some significantly different ways of achieving it.
blog.stihl.co.uk/difference-between-2-stroke-stihl-2-mix-engines/

 

[huskihl]

Not sure why you had to point out the well understood background of Husky, I mention Poulan because it's the most common strato saw out there so maybe it's the one most folk are familiar with.
Agreed that the end result in the combustion chamber is about the same for all strato engines but the Stihl 2-mix has some significantly different ways of achieving it.
blog.stihl.co.uk/difference-between-2-stroke-stihl-2-mix-engines/

Yeah, I didn’t mean to make it sound like that. Sorry about that. My experiences are with the pro saws. Some have a separate strato butterfly (stihl 441, husky 572) and some use mix/air in the bottom half and air in the top half (stihl 462, 372 xtorq).

The differences may be typed differently on their websites, but they all do the same thing. Fresh air goes into the motor next to the intake, through ports in the piston, and back down into the upper transfers. And when the transfers open, that fresh air purges out the spent exhaust before the new charge comes in.

 

[sean donato]

I must be missing something here, they all operate basically the same doesn't matter what badge it wears. What exactly are you asking? The link you have posted is mostly marketing hype.

 

[thompsoncustom]

Got any issues?

Yes all strato's suck, EPA is always messing up a good thing.

 

[Old2stroke]

Yeah, I didn’t mean to make it sound like that. Sorry about that. My experiences are with the pro saws. Some have a separate strato butterfly (stihl 441, husky 572) and some use mix/air in the bottom half and air in the top half (stihl 462, 372 xtorq).

The differences may be typed differently on their websites, but they all do the same thing. Fresh air goes into the motor next to the intake, through ports in the piston, and back down into the upper transfers. And when the transfers open, that fresh air purges out the spent exhaust before the new charge comes in.

Main difference as far as I can tell (have never seen one) is the path of the strato air. In 2-mix, the air is brought in directly to the side of the cylinder and the piston has a small depression on either side, so it's a light piston as opposed to most others that have convoluted passages through the top of the piston to get the air from the carb to the transfers, making a very bulky and heavy piston. It appears that the 2-mix is fitted with a carb that has fixed jets and the tuning is done by varying the amount of strato air, so different tuning issues.
The point in the post was curiosity to see if anyone had actually used one and had any comments on Stihl's claims about their superior design. I guess from the replies, few people have had any experience with it yet.

 

[huskihl]

Main difference as far as I can tell (have never seen one) is the path of the strato air. In 2-mix, the air is brought in directly to the side of the cylinder and the piston has a small depression on either side, so it's a light piston as opposed to most others that have convoluted passages through the top of the piston to get the air from the carb to the transfers, making a very bulky and heavy piston. It appears that the 2-mix is fitted with a carb that has fixed jets and the tuning is done by varying the amount of strato air, so different tuning issues.
The point in the post was curiosity to see if anyone had actually used one and had any comments on Stihl's claims about their superior design. I guess from the replies, few people have had any experience with it yet.

I could be missing something. I believe the term 2 mix is stihl jargon for strato technology. But in every pro saw I have seen, the pistons and cutout are the same, along with how the strato air gets there.

Some strato butterflies open the same time as the carb butterflies, some slightly later. And in some instances, the carb butterfly and strato butterfly are one and the same. But it’s not a tuning thing. Regardless of the manufacturer, there are H, L, and Idle adjustments on the carbs just like older stuff, unless they’re electronic

 

[Dellirium]

Hi i’m from eastern Europe, and here’s my 2 cents about Stihl’s 2 Mix, which is fairly common here presented as the MS 170 and MS180 2Mix. 2 saws that are affordable and kind of useful, until something breaks. Which is also a fairly common thing.
I’ve compared the insides of an classic 180 with a 2 mix style and i found some interesting design choices between the 2

We’ll talk about theese 2 because they belong to the same model on which i had the chance to make rebuilds.
1. Engine
While still using the same piston diameter, that’s the only shared thing among them
The piston has 1 ring on the strato version, and 2 rings on the normal one
Bearings on the strato are 1mm wider than the common 6002 bearings found on the normal, and they cut out 1mm from the width of the oil seal in the strato engine to ensure the same total width as the normal one.
The intake manifold on the strato version is more rugged and less proned to air leaks due to it’s design and how it locks on the cylinder, and it has 3 sepparate channels. 1 which is impulse tube, 2 for the fuel, and the third one for extra air from which the strato technology benefits.

2. The ignition module is also different, it has a kind of “dynamic timing” which advanced and retards based on the current rpm

3. The less nice thing about it is the carburetor.
Carburetors on the 2 Mix have a very limited lifespan. While it uses a Zama S286, or other model from this family based on the production year, which is fairly simillar to the MS 180 normal one, the strato version of this carburetor is very moody about the fuel mix that goes in it, and it’s clogging like hell if not taken care of it. And by taking care i mean extra care, you have to keep it super clean for it to be a reliable carb.

So, the 2 mix version of the 180 is more fragile, more proned to failure, and less rugged (engine related). I feel that the connecting rod from the crankshaft is weaker on the 2mix, the piston is lighter, and the lack of the second piston ring is visible even on a new saw.
So, based on my experience with these saws the 2 mix on the small saws from Stihl is not worth the trouble and the hassle.

Sorry for the tl dr

 

[cscltd]

All POULANs cannot hold a tune.(except 2800-3000 series-lol)
comparing POULAN to Stihl is not best comparison even if they are owned by husky.
like comparing vw to merc and not Audi to merc
its also an evolution thing. Next version of Husqvarna strato will(may) be better than Stihl then next version of Stihl will(may) be better than hq and cycle will repeat.

 

[bwalker]

Yes all strato's suck, EPA is always messing up a good thing.

Strato charging is a great advantage and for a variety of reasons. Fuel economy and performance being two of them.

 

[thompsoncustom]

Strato charging is a great advantage and for a variety of reasons. Fuel economy and performance being two of them.

I'll give ya fuel economy for obvious reasons but you'll have to enlighten me on how it improves performance without emissions in mind.

 

[Old2stroke]

Hi i’m from eastern Europe, and here’s my 2 cents about Stihl’s 2 Mix, which is fairly common here presented as the MS 170 and MS180 2Mix. 2 saws that are affordable and kind of useful, until something breaks. Which is also a fairly common thing.
I’ve compared the insides of an classic 180 with a 2 mix style and i found some interesting design choices between the 2

We’ll talk about theese 2 because they belong to the same model on which i had the chance to make rebuilds.
1. Engine
While still using the same piston diameter, that’s the only shared thing among them
The piston has 1 ring on the strato version, and 2 rings on the normal one
Bearings on the strato are 1mm wider than the common 6002 bearings found on the normal, and they cut out 1mm from the width of the oil seal in the strato engine to ensure the same total width as the normal one.
The intake manifold on the strato version is more rugged and less proned to air leaks due to it’s design and how it locks on the cylinder, and it has 3 sepparate channels. 1 which is impulse tube, 2 for the fuel, and the third one for extra air from which the strato technology benefits.

2. The ignition module is also different, it has a kind of “dynamic timing” which advanced and retards based on the current rpm

3. The less nice thing about it is the carburetor.
Carburetors on the 2 Mix have a very limited lifespan. While it uses a Zama S286, or other model from this family based on the production year, which is fairly simillar to the MS 180 normal one, the strato version of this carburetor is very moody about the fuel mix that goes in it, and it’s clogging like hell if not taken care of it. And by taking care i mean extra care, you have to keep it super clean for it to be a reliable carb.

So, the 2 mix version of the 180 is more fragile, more proned to failure, and less rugged (engine related). I feel that the connecting rod from the crankshaft is weaker on the 2mix, the piston is lighter, and the lack of the second piston ring is visible even on a new saw.
So, based on my experience with these saws the 2 mix on the small saws from Stihl is not worth the trouble and the hassle.

Sorry for the tl dr

Thanks for the info, in my defense, I don't work on many Stihls and did not realize that most of their saws are now strato engines so is the term 2-mix a label for a new and better strato version or are all Stihl stratos the same design. A question for the ms-170 and ms-180, is the carb fully adjustable or fixed jets and is the strato air adjustable?

 

[Dellirium]

Fixed jets and strato air adjustable, the carburetor has a plastic nozzle with 3 ways which matches and air seals with the intake manifold, with 1 of the ways being for adjustable air feed

 

[Franny K]

Why do you think the Stihl ht250 pole saw is conventional yet when that shape of thing is a string trimmer/brush cutter they are stratified charge. Current stuff available, and I may be somewhat wrong. I am not sure I want to start using the term 2 mix without reading a meaningful description from Stihl.

 

[bwalker]

I'll give ya fuel economy for obvious reasons but you'll have to enlighten me on how it improves performance without emissions in mind.

Better scavenging and as a result torque for one.
Improving emmissions isn't a bad thing either. I'd rather not be inhaling unburnt hydro carbons if I don't have to.

 

[bwalker]

Why do you think the Stihl ht250 pole saw is conventional yet when that shape of thing is a string trimmer/brush cutter they are stratified charge. Current stuff available, and I may be somewhat wrong. I am not sure I want to start using the term 2 mix without reading a meaningful description from Stihl.

Emissions are based on a fleet average. So if you produce enough " clean" motors you can also sell some dirty ones.

 

[KostasVolos]

Why do you think the Stihl ht250 pole saw is conventional yet when that shape of thing is a string trimmer/brush cutter they are stratified charge. Current stuff available, and I may be somewhat wrong. I am not sure I want to start using the term 2 mix without reading a meaningful description from Stihl.

https://www.stihl.com/2-mix-technology-economical-and-with-good-lugging-power.aspx

 

[Franny K]

https://www.stihl.com/2-mix-technology-economical-and-with-good-lugging-power.aspx

It says stratified layer of gasses essentially in the text. The picture/ 10 second animation shows the kind of engine with the long transfer tunnels. Other ways of getting a stratified exhaust/air/mix probably count too as long as it is a Stihl but I am left to assume that.