Strato chainsaw good & bad

[CoreyB]

Strato chainsaws have been out for awhile. I have heard many parks and some down sides. But what is the truth.
Do they actually give you better fuel milage? Better power?

Do they run that much hotter?
Shorter life span?

My experience is limited to one saw and I find that it has great power and excellent fuel economy. The heat doesn'tseem much higher than other saws I have.
I have also seen an article where saws in the 45cc range where a cat, non strato gets just as good fuel economy and more power.
So what is the real story?

 

[cus_deluxe]

I have limited experience as well, but it seems that there is a little extra weight, but often a better stock power band. My 575xp has all kinds of power over a wide rpm range. it had better, to make up for being a fat pig

 

[Chainsaw Jim]

It seems like strato and x-torq give the saw the ability to keep the chain speed up while light load or self feed cutting. There doesn't feel like any advantage in the bottom end of the power band...not saying it is under powered.

 

[MarkEagleUSA]

Is X-Torq Husqvarna's name for strato?

 

[Onan18]

Is X-Torq Husqvarna's name for strato?

Yes

 

[smokey7]

I now have 3 strato saws. Only one is a husky the others are poulan. I like the little extra torque they give. The 455 sure is smooth, the Poulan are just a cheap saw and they run but for a life span who knows really. If they use less fuel that means less lube per stroke right? So in the stratos I've been using extra oil at 32:1. Now I do have one of them on a torture test at 100:1 with saber also. I did recently pull the carb off to peek at the crank and it was noticeable that it was less oil then the other same saw at 40:1 but it still looked safe. Since my tortured saw and blower have not blowen up I will likely just go back to running them on a normal 40:1 mix since that's what all my stuff runs on. Good questions tho.

 

[Chris Zautner]

I have my 441 rcm. It's being ported right know. They are excellent saws!!!!

 

[redtractor]

I have also seen an article where saws in the 45cc range where a cat, non strato gets just as good fuel economy and more power.
So what is the real story?

I'd like to see the same saw tested for power switching between a cat muffler and a normal, open breathing muffler. Its all about flow. You'll lose power using a cat. Period. Not really sure about losing any real power with a strato.

 

[T.Roller]

I like the wider power band, and better fuel economy of the strato saws. Only downside is the few ounces of weight which to me is not noticeable.

 

[T.Roller]

I'd like to see the same saw tested for power switching between a cat muffler and a normal, open breathing muffler. Its all about flow. You'll lose power using a cat. Period. Not really sure about losing any real power with a strato.

You also have much more heat build up in a cat. No big deal if your going to gut the muffler but for the average user the heat is going to kill the top end quicker than a non cat saw.

 

[Hinerman]

I like the wider power band, and better fuel economy of the strato saws. Only downside is the few ounces of weight which to me is not noticeable.

Better fuel economy sounds good. But, if the saw uses less fuel, then less oil is getting to the P/C and crank, in theory at least. Has this been a problem? If so, does running a richer mix compensate?

 

[T.Roller]

Better fuel economy sounds good. But, if the saw uses less fuel, then less oil is getting to the P/C and crank, in theory at least. Has this been a problem? If so, does running a richer mix compensate?

Its not so much that it has less mixture running thru that saw, but that it doesn't blow near as much unburnt mix out the exhaust before its ignited. A charge of fresh air is layered in the cylinder so it blows out the exhaust.

 

[CoreyB]

Better fuel economy sounds good. But, if the saw uses less fuel, then less oil is getting to the P/C and crank, in theory at least. Has this been a problem? If so, does running a richer mix compensate?

I have heard this from a few as well. Part of the reason for me asking.
However when looking at my piston (I know limited info) through the exhaust side. I have what looks to be a fair bit of oil on the side of the piston. I don't tune overly rich so are Stratos lubricating as well as non Stratos. Let's say non cat versions to keep things more even.

 

[CoreyB]

Its not so much that it has less mixture running thru that saw, but that it doesn't blow near as much unburnt mix out the exhaust before its ignited. A charge of fresh air is layered in the cylinder so it blows out the exhaust.

I think that helps me wrap my head around it better. Thanks.

 

[CR888]

Some guys who mill or do tree service spend many hours in close proximity to a running saw, the health advantage of strato saw to people like this is huge. Although this is a major benefit of the tech, there are other advantages too in performance, fuel efficiency etc. All two stokes rely on the scantyest amount of oil to keep them alive, strato's may be worse but I am yet to have or hear of a seizure or premature wear directly linked to this the tech with regard to top ends. Bottom ends their may be evidence of issues with bearings being starved of oil. But it only appears apparent in a select few models.

 

[Onan18]

Some guys who mill or do tree service spend many hours in close proximity to a running saw, the health advantage of strato saw to people like this is huge. Although this is a major benefit of the tech, there are other advantages too in performance, fuel efficiency etc. All two stokes rely on the scantyest amount of oil to keep them alive, strato's may be worse but I am yet to have or hear of a seizure or premature wear directly linked to this the tech with regard to top ends. Bottom ends their may be evidence of issues with bearings being starved of oil. But it only appears apparent in a select few models.

Strato technology does not work that way, you are still getting the full air/fuel charge into the crankcase, the clean air passes through a different set of intake ports, through the notches in the piston, and is injected into the primary transfers ahead of the air/fuel charge ( they do not mix much because of a pressure differential) The clean air is only ever in the top end and only used to scavenge the exhaust. If anything Strato engines tend to be set a little fatter because the piston normally closed off the exhaust port before all of the clean air is out and therefore that little bit them becomes part of the mixture in the cylinder fill and has to be compensated for by adding more fuel.

Joe

 

[idiotwithasaw]

Has anyone who has gutted the strato noticed any gains or losses because of it?

 

[idiotwithasaw]

The thing about lubrication on a strato is that it's still getting fuel and oil mix in the bottom end, that part is still a traditional 2 stroke. the mix comes through the carb into the bottom end and up through the transfers and out the exhause. what's different is that they added a step that doesn't really affect the rest of the process that sweeps fresh air into the chamber and put the exhaust before the fresh charge enters. Now an argument could be made that the smaller venturi and jetting in the traditional part of the carburetor may be putting less mix into the bottom end, but I doubt it. I have often wondered if putting a larger carb onto a strato saw would yeild any gains.

 

[CoreyB]

So to me to sounds like the strato would not run any hotter then a conventional.

 

[idiotwithasaw]

To me where I think they went backwards on is, in the case of husqvarna went from a quad port design to a dual port transfer and dual fresh air ports. If they could go back and have quads fuel mix transfers and dual fresh charge transfers there could be lots of gains had. but that's just my uninformed opinion.