4 stroke chainsaw is it in the future?

[Bob Wright]

It must have an all position oil pickup tube so the enginge always gets oil no matter which way you tip the saw. So now you have bar oil, engine oil and gasoline. I can see the questions on AS in the future, which hole do i put the oil in????...Bob

 

[Duke Thieroff]

Echo will be the first on the market with a four mix. With the purchase of Shindiawa Echo has all of the technology at it's disposal. Shinny has had four mix trimmers on the market since around 2006, I worked for a shop was one of the development shops for Shinny, we got to hand them out (string trimmers) to a couple of commercial users and see how they held up.
I can easily see Echo taking advantage of this in the near future.

I have heard a lot about the advancements that Shinny was making, but also a lot of how Echo has scrapped a lot of of that stuff.

We will have to see.


Chris

 

[Andyshine77]

It must have an all position oil pickup tube so the enginge always gets oil no matter which way you tip the saw. So now you have bar oil, engine oil and gasoline. I can see the questions on AS in the future, which hole do i put the oil in????...Bob

No. My understanding is that it operates like the Stihl 4-mix engines. You still use 2 cycle oil in the fuel and a small passageway allows some of the oil mix from the case to makes it's way to the valves.

 

[ironman_gq]

I have used those little hondas and they are a nice little engine till you turn em the wrong way and they turn into an oil burning mesquito fogger till you straighten em out. They are also only about 1.3hp so not real practical for a saw but for trimmers and concrete vibrators they are perfect.

 

[SawTroll]

Here are a few pics of the 4-stroke Dolmar PS500V, for those who haven't seen it.

As far as I know the specs were 50cc, 14.3lbs and 3.4hp

Yes, and it is an old story dating from 2005 or so.....:msp_wink:

I guess the weight penalty just was too high?

 

[drkptt]

Bombardier did not originate this technology, either. They now own it because they bought it, fair and square when they acquired Puch. Puch invented this very novel intake/scavenging scheme back in the late '70's for their twin carburetor race dirt bikes, with one carb feeding a piston port arrangement and the other a rotary valve setup. The two carbs were not identical, and one ran much leaner than the other. The bike was very powerful for its day, but the system was too expensive to compete with the Japanese dirt bikes, which were starting to be very good and way cheap compared to anything from Europe or the USA.

The technology languished for years until Bombardier got hold of it, updated the concept and is using it in most if not all their two-stroke engines. The Evinrude engines are just thrashing Mercury in the outboard market because of the E-Tech system. I got all this from a close friend that worked for Bombardier for 16 years before getting layed off at the end of 2008, Christmas, in fact.

Jimbo

I think you're confused. Bombardier bought OMC (Johnson/Evinrude) out of bankruptcy. OMC had the Ficht system in production and E-TEC in development. Both are direct-injection systems using electro-mechanical injectors, controlled by an engine management system, to spray fuel into the cylinder. Not a refinement of the Puch mechanical system.

 

[Bob Wright]

No. My understanding is that it operates like the Stihl 4-mix engines. You still use 2 cycle oil in the fuel and a small passageway allows some of the oil mix from the case to makes it's way to the valves.

That makes sense. Thanks...Bob

 

[drkptt]

At this point in time there's no valid reason to ever develop and market a 4-stroke chainsaw. If regulations were to be drastically tightened up they would favor 2-strokes over 4-strokes due to 4-strokes emitting higher levels of NOx. Currently produced stratified 2-strokes put out an exhaust that's rich in oxygen and low in NOx. Put a big oxidizing catalyst on that and you can burn the emitted hydrocarbons down to nothing. Reducing NOx is a different story; you have to have a 3-way catalyst and closed-loop control to run at stoichiometric air/fuel ratio. So that's adding a micro-processor controlled fuel system and exhaust oxygen sensor to an engine that's already disadvantaged by higher weight and fragile poppet valves trying to live at 14,000 rpm. Makes no sense. The fact that Dolmar started developing a 4-stroke 8 to 10 years ago yet never sold one should be proof of that.

 

[Edge & Engine]

Shindaiwa has had 4-stroke handhelds in production since 2001. Stihl's 4-mix came out about a year later. Not sure about Honda's micro technology, but it's been out for quite a while.
Three major handheld equipment manufacturers have tested 4-cycle chainsaw prototypes: Dolmar, Shindaiwa and Stihl. Supposedly Stihl was "actively testing" a large displacement, OHC horizontal cylinder 4-cycle chainsaw back in 2007-2008. However, at least in Dolmar's case the technology nor the market was/is ready for it. The main reason is price - in Dolmar's case, you could buy a more powerful, 65cc range 2-cycle chainsaw for the same price. I would assume that this is the same thing that the other manufacturers ran into.
However, since then most if not all of the focus has switched to stratified designs...obviously, Husqvarna and Stihl are both using it already. Dolmar is implementing it, we should be seeing stratified Dolmars before too long. There's a good reason that they are pursuing that instead of 4-stroke. I'd say that's the future of chainsaws, at least for now.

 

[Boskaerm]

what about a Wankel engine? shouldn´have the weight problem, with no cams valves etc.

 

[fields_mj]

Yeah, but if they go to a 4-stroke, how will you be able to keep the mosquitos at bay while cutting during the summer? :msp_wink:

 

[Eccentric]

what about a Wankel engine? shouldn´have the weight problem, with no cams valves etc.

It's been done, Sachs-Dolmar (and possibly at least one other manufacturer that I can't remember) built some Wankle powered saws. A few collectors here have 'em. They sound fantastic, but there were issues with them. IIRC, the main problem is rotor tip seal life, and they're extremely thirsty.



Here's the listing for one of those saws on Mike Acres' site:

http://www.acresinternet.com/cscc.n...bc2f06b3baf2203388256af90060c147?OpenDocument

If you search youtube for "wankle chainsaw" you can find videos of them. There was a cool one made by some German or Scandinavian guys IIRC.

 

[Boskaerm]

It's been done, Sachs-Dolmar (and possibly at least one other manufacturer that I can't remember) built some Wankle powered saws. A few collectors here have 'em. They sound fantastic, but there were issues with them. IIRC, the main problem is rotor tip seal life, and they're extremely thirsty.

Seen and heard the Dolmar on you tube, it´s fantastic!
Know it has some problems, but Mazda build a Le Mans winning group c racer! Then it most be possible to build a functional chainsaw!
And Fuel economy was very important on Le Mans during the group c era!

Btw whats the name of that Dolmar?

 

[Eccentric]

Seen and heard the Dolmar on you tube, it´s fantastic!
Know it has some problems, but Mazda build a Le Mans winning group c racer! Then it most be possible to build a functional chainsaw!
And Fuel economy was very important on Le Mans during the group c era!

Btw whats the name of that Dolmar?

The 1975-vintage Sachs Dolmar wankle powered chainsaw was a KMS-4.

 

[Knuckles]

I doubt this, as Stihl is going away from 4 strokes altogether. Dolmar does and has had a working 4 stroke saw, some here have even ran them, but as of now it doesn't look like they will be put into protection.

What info do you have on this? I was under the impression that the 4 mix was the future of Stihl.

Ahh the memories. I remember all the nay sayers that pissed on Yamaha in 2001 for building a competitive 4 stroke MX bike. Look where they are now.

A 4 stroke is definately in chainsaws future. Maybe a few years away yet, but it's coming.

 

[drkptt]

A 4 stroke is definately in chainsaws future. Maybe a few years away yet, but it's coming.

Why?

 

[Andyshine77]

What info do you have on this? I was under the impression that the 4 mix was the future of Stihl.

Ahh the memories. I remember all the nay sayers that pissed on Yamaha in 2001 for building a competitive 4 stroke MX bike. Look where they are now.

A 4 stroke is definately in chainsaws future. Maybe a few years away yet, but it's coming.

The info is from Stihl, and it's not really a secret. The 4-mix engines work well enough, but they're heavy, more complicated, harder to work on, more expensive to produce, don't turn enough RPM's. Anything a 4-mix can do a 2-cycle strato can do better IMHO.

 

[Knuckles]

Why?

Why not?

The info is from Stihl, and it's not really a secret. The 4-mix engines work well enough, but they're heavy, more complicated, harder to work on, more expensive to produce, don't turn enough RPM's. Anything a 4-mix can do a 2-cycle strato can do better IMHO.

I have a few opinions on your post:

but they're heavy

Don't worry. They'll get lighter.

more complicated, harder to work on

This is irrelevant. Folks were afraid of fuel injected cars 20yrs ago.

more expensive to produce

Can't argue this.

don't turn enough RPM's

In about 10-15yrs someone's going to build a 50-60cc 4 stroke saw that turns 11k rpm reliably.

The 2 stroke is a dying breed. As the years go by, there are fewer and fewer 2 stroke engines available. Look a watercraft, snowmobiles, motorcycles, lawn mowers, weed whackers, leaf blowers. Chainsaws are the last of it and I don't believe they'll hold out forever.

 

[Andyshine77]

Why not?



I have a few opinions on your post:

Don't worry. They'll get lighter.

This is irrelevant. Folks were afraid of fuel injected cars 20yrs ago.

Can't argue this.

In about 10-15yrs someone's going to build a 50-60cc 4 stroke saw that turns 11k rpm reliably.

The 2 stroke is a dying breed. As the years go by, there are fewer and fewer 2 stroke engines available. Look a watercraft, snowmobiles, motorcycles, lawn mowers, weed whackers, leaf blowers. Chainsaws are the last of it and I don't believe they'll hold out forever.

Fuel injection is not a valid argument as it was simply a different way to regulate fuel in a 4 stroke engine, the engines for the most part were the same. Adding more moving parts to anything is adding more parts to ware out or fail, plane and simple. More parts = more weight. Working on them takes longer and time = money, not only for the repair shop/manufacture, but also the owner of the product.

You're really looking at this through a straw, there is much more to manufacturing than most know, from R&D to assembly, all of which is more involved aka $$$ with 4 cycle engines, something Stihl and most hand held OPE manufacture are not familiar with. Mercury marine, Honda and others are.

Will two cycle engines be around forever? no, but one could say the same for any internal combustion engine. Fact is OPE two strokes are hear to stay for the foreseeable future, likely until we're all gone.

 

[166]

In about 10-15yrs someone's going to build a 50-60cc 4 stroke saw that turns 11k rpm reliably.

I believe the Dolmar 500V turns 12,500. Also if Dolmar released the 500V it would have a price tag in the $1200-$1400 range.