New saw technology

[stltreedr]

I attended a local Arborists Association meeting last night and the guest speaker was a rep from a local equipment (stihl) dealer. Some of you likely already know some of what was presented, but I thought I would share anyway.

The guest brought examples of the new carburetors, some of which are electronic, others have a 'dual throat' design to aid in reducing idling emissions. The electronic carbs have almost no adjustment screws, and field repairs are going to become more difficult. (These changes are obviously driven by the EPA) He also said that he believes saws will be fully fuel-injected within 10 years.

Another way companies are battling EPA requirements is to use 4 cycle engines... Makita already has a 4 cycle cut-off saw. He did not believe that Stihl is investing in this technology, but other companies will certainly give it a try. On that note, I recently attended a motocross race, and 19 out of 20 bikes are now 4 cycle... When I was growing up, ALL of the racing bikes were 2 stroke... So don't say that it's impossible!

Lastly, I was shocked to see that Stihl already produces a backpack blower with.....ELECTRIC START! It was demonstrated for us and is pretty cool. The battery and starting mechanism is very small, and it still has the pull-cord for backup. The rep said that he fully believes we will see this technology in chainsaws within 5 years.

Just a little FYI- curious to hear your thoughts.

 

[Philip Wheelock]

The local Husky & Stihl shops are not wild about electronically-controlled carbs. If a saw won't start, diagnostic software is useless and you're left with replacing parts until it does. I like the clean-running, strong torque characteristics of my 4-cycle trimmer & backpack blower, but they're typically running at a constant rpm; the throttle response seems too slow to be useful on a chainsaw. FI may be fine, but I don't like the idea of pushing a primer 6 times every time I want to start a chainsaw. Electric start is a good idea on a backpack blower, but not on anything else.

Bottom line: while I believe in technological advances, I think it's more important to provide the most bulletproof chainsaw designs possible for loggers, fire crews and the like; the EPA should not get in the way of that.

 

[Chris-PA]

The guest brought examples of the new carburetors, some of which are electronic, others have a 'dual throat' design to aid in reducing idling emissions. The electronic carbs have almost no adjustment screws, and field repairs are going to become more difficult. (These changes are obviously driven by the EPA) He also said that he believes saws will be fully fuel-injected within 10 years.

Both of these are already common. The electronic carbs are the AutoTune/Mtronic system. The dual throat carbs are a mechanically simpler strato carb that does not use a separate air valve. These are used with electronic feedback (MS421) and without (543XP and I think the 372XP).

Neither one is any more mechanically complicated than a conventional carb (no more moving parts) - the dual throat is just a big carb with some fixed dividers in the throat, while the AT/MT carbs have a fuel solenoid in place of the L and H screws.

 

[stltreedr]

Maybe if the saws already had a battery, and electric fuel pump, you wouldnt have to prime it?? Seems like that and electric start would go hand in hand

 

[heyduke]

I attended a local Arborists Association meeting last night and the guest speaker was a rep from a local equipment (stihl) dealer. Some of you likely already know some of what was presented, but I thought I would share anyway.

The guest brought examples of the new carburetors, some of which are electronic, others have a 'dual throat' design to aid in reducing idling emissions. The electronic carbs have almost no adjustment screws, and field repairs are going to become more difficult. (These changes are obviously driven by the EPA) He also said that he believes saws will be fully fuel-injected within 10 years....

Dual throated carbs have been used by Husqvarna for several years. You will find them on the strato 372's. I think they are a less expensive alternative to the more common method of dual "progressive" throttles, one in the carb and another for the fresh air ducts, like you'd find in the husqvarna 576 and certain poulans. I wonder if Stihl is licensing that technology from Husqvarna. I can't imagine the techs at my local Stihl dealer attempting to troubleshoot an electronic carb. They are severely challenged by simple problems in old saws.

 

[beentown]

I am all for it except the cost. My Husqvarna dealer and tech both love the AT.

Sent from my SM-G900V using Tapatalk

 

[Philip Wheelock]

Maybe if the saws already had a battery, and electric fuel pump, you wouldnt have to prime it?? Seems like that and electric start would go hand in hand

Maybe. I would still be concerned about weight and more assemblies that can fail. Suppose the battery or pump fails while fighting a forest fire? I suppose you could have a primer bulb, but still...

 

[Conquistador3]

It's really intriguing that, after over a decade spent lobbying to have two stroke engines completely banned (leading for example to the disappearance of two stroke lawnmower engines), Honda has started filing patents for two stroke engines clearly intended for power equipment applications.
More intriguing is the fact that is not new technology by any measure: it's mostly based around work Honda introduced over two decades ago on the EXP-2 Paris-Dakar racer, the main difference being the EXP-2 had an exhaust port with variable timing while the new patents clearly show a pushrod-activated poppet valve.

Honestly I don't see that exact technology being used in chainsaws (too heavy due to DFI and apparently the poppet valve design can only effectively be used with a relatively long stroke) but surely something is moving. Honda is the world's largest Otto-cycle engine manufacturer and if after years of sweeping two stroke engines under the rug they became interested in them, it means they are seeing money to be made one way or the other.

 

[Mwmx54]

Ive been riding dirt bikes my whole life, and when Yamaha first released the yz400f(four stroke race bike) nobody thought they'd be able to compare, fast forward several years and the 4 strokes, while in the racing world, can run twice the cc's in the same 2 stroke class(i.e., 450 4 stroke, races in the 250 2stroke class) not many people race the 2 strokes anymore, the 4 strokes rev out at 13,000 rpms, and even when running on carbs had unreal throttle response and torque, but they are significantly more sophisticated engines, and require a lot more maintenance and waaaayyy more money to repair. If the top end needs refreshing, not including a new cylinder and head just piston and valves, your looking at upwards of $400-800+, versus a new piston and rings for $100. They ain't your typical four strokes like an XR400. They are very high performance engines, they even have a crf150 race bike for the 85cc 12-16yr old classes. Though most small bore racers are on 2 strokes.

 

[heyduke]

Ive been riding dirt bikes my whole life, and when Yamaha first released the yz400f(four stroke race bike) nobody thought they'd be able to compare, fast forward several years and the 4 strokes, while in the racing world, can run twice the cc's in the same 2 stroke class(i.e., 450 4 stroke, races in the 250 2stroke class) not many people race the 2 strokes anymore, the 4 strokes rev out at 13,000 rpms, and even when running on carbs had unreal throttle response and torque, but they are significantly more sophisticated engines, and require a lot more maintenance and waaaayyy more money to repair. If the top end needs refreshing, not including a new cylinder and head just piston and valves, your looking at upwards of $400-800+, versus a new piston and rings for $100. They ain't your typical four strokes like an XR400. They are very high performance engines, they even have a crf150 race bike for the 85cc 12-16yr old classes. Though most small bore racers are on 2 strokes.

Recreational bikes are an expensive hobby. Race bikes are an obscenely expensive pursuit. Chainsaws, on the other hand are practical tools for making money. Most of the technology that makes 2stroke bikes go fast, like exotic valves on the intake side aren't practical on the simple chainsaw. Stratofied charge systems, like husqvarna's "xtorq" were conceived to make saws run cleaner but actually improved performance and fuel economy and are not expensive or overly complex. You have to wonder if that technology could be used for dirt bikes. i miss the days when you could overhaul your honda/yamaha/suzuki 250cc 2stroke with a few hours of work and $150 as opposed to a 4stroke that took a week and $500.

 

[Mwmx54]

Yeah, I can't imagine what a 150cc-200cc race type four stroke engine would be like on a chainsaw. I suppose you could probably go up to an 8 or even 9 tooth sprocket and not ever have to worry much about it bogging down in the cut, and it would probably make the EPA happy, but it would open a whole new realm of problems, trying to start a dirt bike with an intake valve that tightened up a fraction of a millimeter is damn near impossible, let alone trying to do it with your arm. Then what, send the head in to get new valves installed and the seats re-cut. You are right, it's not very practical. In my non competitive riding I do these days, I'll take the 2 stroke any day, working on bikes is fun, but always working on them gets real old and expensive and that sound and smell of the 2-stroke just makes it even better. There Is atleast one company out there that made direct injection kits for the 2 stroke dirt bikes. And look at this, although Honda has been saying they were gonna do this for several years now.
http://www.gizmag.com/honda-two-stroke-with-fuel-injection-patent-filing/38529/
Although they discontinued the 125cc+ 2 strokes, along with the other big dirt bike companies years ago, maybe they'll make a comeback. Yamaha started re-producing them again a few years ago, with no changes since about 2006.

 

[Chris-PA]

If you look at a typical chainsaw you see that that there really isn't any room to put much of anything. You are basically holding an engine in your hands - probably the most elemental use of an internal combustion engine, which is part of the appeal. I'm very impressed with both the strato and AutoTune designs, precisely because they are so simple.

Strato requires no additional moving parts, at least when the new dual throat carbs are used. Otherwise it only requires an additional throttle plate.

AT can control the mixture with no additional sensors other than a throttle switch and air temperature, and one fuel solenoid - that's pretty impressive.

 

[svk]

Take a look at the newer two stroke technology offered by Bombardier. They have ultra clean burning two stroke outboards that are both reasonably light, powerful, and supposedly more fuel efficient than comparable 4 strokes. The only trade off is you need to run their very expensive synthetic oil. I would expect this technology to trickle down to smaller engines as patents expire.

 

[pro94lt]

ht101 br600??? Are those stihls 2 strokes?

 

[Philip Wheelock]

BR600 is a 4-stroke, aka 4-Mix.

 

[7sleeper]

Not any new info here. And Dolmar had a 4 stroke chainsaw (just search for Dolmar 500 V) almost a decade back in the trial runs. Too bad they never made a full production run.

7

 

[sawfun]

It might make sense to use a four stroke on a large saw (120cc catagory) where the weight is already heavy (we are used to) and torque is important for long bars or tough wood, though, this is a very small part of the market with large trees on the decline. However, it may make for a good test platform.

 

[zogger]

Take a look at the newer two stroke technology offered by Bombardier. They have ultra clean burning two stroke outboards that are both reasonably light, powerful, and supposedly more fuel efficient than comparable 4 strokes. The only trade off is you need to run their very expensive synthetic oil. I would expect this technology to trickle down to smaller engines as patents expire.

Would those be liquid cooled though?

 

[stltreedr]

Many good points here...i personally think that whatever direction they go, we probably wont recognize chainsaws in 20 years. Ive tried the new battery powered stihl and it was pretty impressive... its no 200t, but impressive nonetheless. As battery technology improves, i wouldnt be surprised to see many more battery operated small saws.

 

[schpankme]

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