Modifying Strato/X-Torq saws...

[MCW]

Hi gents.

Just a quick question from a mechanically handicapped saw user.
There have been a number of strato style saws being modded on AS lately and I have some questions...

Do they lose their fuel saving efficiency once modded?

For example, will a modified 372 X-Torq still be roughly 20% more fuel efficient than a similarly modded 372XP?

After modifying can they still be classed as a strato type saw or are many of these features ground away in the process?

Thanks for any replies and my understanding of how these more modern saws work is limited to the knowledge that they still run on 50:1 fuel, just for longer

Matt

 

[sunfish]

After following most of the strato builds here, I've come to the conclusion that it might be best to leave them stock, or just do a MM and be done with it. I'm sure the porting dudes will figure something out though.

 

[flyank]

"mechanically handicapped saw user"

- sorry, had to chime in off topic here... I love that quote.

 

[mweba]

Depends on how they are modified. On my 372 xt, the first porting I did to it, the strato splitter was removed in order to "stuff" the strato ports with fuel. In this case, the initial charge entering the combustion chamber was mix instead of fresh air. This configuration was by no means fuel efficient.

The way my xt stands now, the strato function was left alone. Fuel mileage was retained. The current cylinder is conventional woods ported.

Hope that ramble helped.

 

[MCW]

After following most of the strato builds here, I've come to the conclusion that it might be best to leave them stock, or just do a MM and be done with it. I'm sure the porting dudes will figure something out though.

That was my initial impression too

"mechanically handicapped saw user"

- sorry, had to chime in off topic here... I love that quote.

I'll even let you use that quote if you'd like

Depends on how they are modified. On my 372 xt, the first porting I did to it, the strato splitter was removed in order to "stuff" the strato ports with fuel. In this case, the initial charge entering the combustion chamber was mix instead of fresh air. This configuration was by no means fuel efficient.

The way my xt stands now, the strato function was left alone. Fuel mileage was retained. The current cylinder is conventional woods ported.

Hope that ramble helped.

Thanks for the ramble and yes it helped The splitter is what I have seen being removed in most mods on AS which is why I questioned the fuel economy. I gathered that by modifying it too extensively that any fuel savings from the strato design would be basically null and void.

 

[mweba]

After following most of the strato builds here, I've come to the conclusion that it might be best to leave them stock, or just do a MM and be done with it. I'm sure the porting dudes will figure something out though.

Many saw builders work these over with great success. AS in the world of porting is a small percentage of the examples in the field. One very public bad experience does not necessarily mean this is the norm. Gains are there to be made and unfortunately strato is the world we live in.

 

[MCW]

Many saw builders work these over with great success. AS in the world of porting is a small percentage of the examples in the field. One very public bad experience does not necessarily mean this is the norm. Gains are there to be made and unfortunately strato is the world we live in.

Do the gains negate the fuel efficiency though if heavily modified? If so then do you still see any benefits over a non strato saw?

P.S. I still haven't got a good grasp on the concept of strato

 

[mweba]

Give it a go in another description. Completely ignore all the extra runners, splitters and transfers.
In essence, all an strato does is "chase" or "scavenge" the burnt charge out with fresh air using two extra ports that open before the mix transfers. By doing this, fresh air is lost out the exhaust instead of unburnt mix making the system more efficient. A common misconception is the a strato runs leaner due to using less fuel. This is not the case, it just wastes less out the exhaust. The charge being burnt is the same. This is how they get the clean emissions.

Now there are variances already to this design....372xt does it a little different with tranfer timing but the overall concept is the same.

Really nothing wrong with a starto IMO, just a new challenge.

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[CentaurG2]

Sharp chain and efficient cutting techniques are the only mods you really need. I have yet to see a decent study that shows greater or less fuel efficiency between stratos and regular saws let alone heavily modified units. We are just asked to believe by the manufactures that stratos are more fuel efficient.

 

[mweba]

Sharp chain and efficient cutting techniques are the only mods you really need. I have yet to see a decent study that shows greater or less fuel efficiency between stratos and regular saws let alone heavily modified units. We are just asked to believe by the manufactures that stratos are more fuel efficient.

I agree that the best and most overlooked "mod" is proper chain maint.

All manufacturers rely on convincing the consumer there product is better. Most can be won over by a simple statement rather than science.

Having run both the 372xt and OE side by side on many jobs. The Xt is more fuel efficient, twenty percent.....not sure but either way it gets filled less no matter the operator.

Just my real world experience, others may differ.

 

[Chris J.]

Sharp chain and efficient cutting techniques are the only mods you really need. I have yet to see a decent study that shows greater or less fuel efficiency between stratos and regular saws let alone heavily modified units. We are just asked to believe by the manufactures that stratos are more fuel efficient.

I have no idea about a "decent study," but I'll trust the word of the AS members who say the strato saws are fuel sippers.

MCW, judging from your posts, I somehow doubt that you're completely "mechanically handicapped." :cool2:

 

[sunfish]

Thanks mweba!

I am actually looking forward to getting a strato saw at some point. The reports so far have been positive, some very positive.

 

[MacLaren]

So,what I gather is that they can be ported and most have no problems porting them. Thats good to know.

 

[blsnelling]

I have ported quite a few strato saws, most of them with great success. I treat each model differently. The MS261 is one that I completel remove all strato clean air from. All of the air is charged with fuel. I tried it leaving the strato system intact, and it didn't respond like I wanted. Most other models I leave intact. This would include the little Ryobi/Redmax saw, which is the strongest 40cc class saw I've ever ported. The MS441 and MS362 also respond very well to porting and leaving the strato technology intact. The only saw I've had reliability issues with was the 372XP XT, and I removed it's strato stuff since it was designed VERY similiarly to the MS261. I've only done the one and did not try it leaving the strato still functional. The bottom line is that strato saw respond very well to porting. If the strato functionality is left functional, it can't help but save on fuel. One case that helps prove this, is that the MS261 H needle must be backed out 2 1/2 turns once I'm done with my mods. That's how much more fuel it needs to be rich enough. Fortunately, the carb still responds very well to adjustments at that point.

 

[blsnelling]

So,what I gather is that they can be ported and most have no problems porting them. Thats good to know.

That is correct.

 

[CentaurG2]

I agree that the best and most overlooked "mod" is proper chain maint.

All manufacturers rely on convincing the consumer there product is better. Most can be won over by a simple statement rather than science.

Having run both the 372xt and OE side by side on many jobs. The Xt is more fuel efficient, twenty percent.....not sure but either way it gets filled less no matter the operator.

Just my real world experience, others may differ.

So with higher efficiency (assuming the take size is equal), do you get more wood cut per tank or do you get a longer run time per tank or both?? I tried to get my hands on a 372xt autotune earlier this year but the dealer and I did not see eye to eye. I will eventually get one and give it a go against a non-strato 372xp.

Only strato I do have is a redmax ebz8001 and there is nothing fuel efficient about that thing. It just plain drinks fuel. Displacement is 71.9cc, fuel capacity 77.7oz, run time per tank about 1 hour at WOT under load. Husky 372xp, displacement 71cc, fuel capacity 26.08oz, run time per tank at WOT under load is about 18 to 20min. I don’t see a lot savings between these two machines real world. Yup its like comparing apples to pine nuts but it is at least some numbers to work off.

 

[MacLaren]

This is a good thread. Thanks for posting it Matt. Im glad MWEBA got in there and gave us his input. Know, goin on what MWEBA has said I may just have to get one of these babies and have it ported. That may be a while though as I may be gettin a 90cc already...lol!!......CAD is for real!

 

[mweba]

So with higher efficiency (assuming the take size is equal), do you get more wood cut per tank or do you get a longer run time per tank or both?? I tried to get my hands on a 372xt autotune earlier this year but the dealer and I did not see eye to eye. I will eventually get one and give it a go against a non-strato 372xp.

Only strato I do have is a redmax ebz8001 and there is nothing fuel efficient about that thing. It just plain drinks fuel. Displacement is 71.9cc, fuel capacity 77.7oz, run time per tank about 1 hour at WOT under load. Husky 372xp, displacement 71cc, fuel capacity 26.08oz, run time per tank at WOT under load is about 18 to 20min. I don’t see a lot savings between these two machines real world. Yup its like comparing apples to pine nuts but it is at least some numbers to work off.

Redmax to 372 has to many variables. Really all I can add for educated info is the comparison side by side 372 old and new. The XT gets the same work done with less fuel and less down time...if not more done because of less down time.

As you stated earlier though, chains can make more of a difference with speed of production....for that matter, its hard to get anyone to work for you these days that stays consistently productive LOL

 

[Terry Syd]

I left my strato function intact when I ported it. I'm glad when the tank finally runs dry, I can take a break/collapse.

The strato saws have a much greater time/area for the intake cycle. It is not just the intake port that feeds the crankcase, but the transfer ports as well. A conventional two-stroke is limited by the width of the intake port.

The increase in the area of the intake cycle allows the strato to 'gulp' the mixture a lot quicker. You don't need as much intake timing to fill the crankcase, that translates into an engine with more torque.

 

[spike60]

The only saw I've had reliability issues with was the 372XP XT, and I removed it's strato stuff since it was designed VERY similiarly to the MS261. I've only done the one and did not try it leaving the strato still functional.

Some people here on the site are eager to step on someones toes, and some are so afraid of doing so, that they are afraid to say what they are thinking. I'm neither, so.............

Brad, the only "issues" the 372XT has had is your porting. :msp_smile:

I can't sit here quietly if there's going to be any attempt at all to shift the spotlight regarding that failure to the saw itself. Chipmonger's saw is the only 372XT failure that I know of.

You know I'm not one of those guys that will play a game of "gotcha!" and sit here and try to nail you to the cross about it. Just a simple mistake, that any of us can make. I'm sure we all have a few things in the corner of the shop that we've screwed up.

But recall, you told me personally that you went too far with the exhaust port, and that you tried to correct that error, and save the cylinder, by lowering the port. It worked for a while, but of course the original mistake was still there, and the ring caught a second time. It's not a big deal; just a little "ooops!" that any of us can make from time to time.

There will be no damage to your image or credibility to simply say, "Yeah, I kind of over did it with that one and screwed it up."

You did all the right things for Chipmonger. You paid for the first piston, and you paid for the replacement XPW P&C. I'm not sure how many builders would have done the same. So, do another "right thing" regarding that saw, and just admit to a simple porting error.

But any suggestion that there might be something wrong with the design of the 372XT is not cool at all, and I won't sit here without responding. A lot of members look up to your opinion on things, and they may read a comment like the one I quoted you and conclude that the 372XT is a saw they should steer clear of. That is certainly not the case, as those things have been extremely reliable.

I was saving an original 372 in the box, that I figured I might want to be able to pull out a few years from now. After running the XT, I decided to sell the original I had been saving. Boys, the XT is one good saw.