found this little gem of info future of 2 strokes

[murf007]

The Future Of Two Strokes And Your Dirt Bike



This is a unique page on my site. It relates to the future of two strokes in general, but ties in with how this will affect you and your choice of dirt bikes. The information here comes from Tim Hickox who will be putting up regular posts using his many years of experience with engine design.

So, if you are interested in what's happening out there in regards to engine design and dirt bikes... read on and be sure to check back as this page is updated!

A quick introduction with Tim...

"I can't put a lifetime into a bottle, but: I got my first motorcycle when I was 14. After owning a Greeves, CZ, OSSA, Honda, Suzuki, et al., I had a pretty good idea of what worked and what didn't. Engineering was my destiny. I was service manager for a motorcycle importer/manufacturer; I was Technical Editor of a motorcycle magazine and then Technical Analyst for the Motorcycle Industry Council. I worked for Honda on the early development and testing of their trials machines, and so on. I wanted to stay in the motorcycle industry, but it was going in the "wrong" direction for me (pushing everything up-market to maintain dollar-volume as unit-volume fell). So I went into aerospace. I worked on the Space Shuttle and on many earth-observation satellites. I am now writing a book (philosophy) and working on a unique vehicle (with a two-stroke engine!) that can get 300-mpg at 65-mph."

Tim Hickox




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3rd Nov 2008:
I understand the point on dirt-bike specifics, but if we really try to limit it so, there isn't much to talk about! This is the problem! What I really think is needed is to offer an alternative to the misinformation that has confused so many people.

There are many ways to build two-stroke engines. People must understand that what has been offered to motorcyclists in the past is not "a two-stroke engine". That is, the future of two-stroke dirt bikes, if there is going to be any future, need not be, in fact cannot be, more of the same. The guys seem to think that what was, is no longer acceptable, therefore we have to chuck the whole idea of "two-stroke engines" and switch to four-stroke engines. You see, what we really want to talk about is... two-stroke engines of the future! But that future is not here, so how can we possibly put limits on what it "is". The 2009 Skidoo 600 E-TEC is the best two-stroke going now that could represent the direction in which some future motorcycle engines may go.

But I must make this point: If the two-stroke engine does not return as a viable transportation option for two-wheelers in developing countries, I think it will die. I think this is really what the Japanese companies have been saying. If they can't build and sell two-stroke bikes to the masses, at the low-end of the spectrum, they aren't going to support the type anywhere. So... what may be needed now, to ensure the future of "two-stroke dirt bikes", is a low-tech (i.e. cheap), clean, economical two-stroke motorcycle. The "death" of two-stroke dirt bikes has come after the loss of two-stroke motorcycles in general; and I believe that the future of two-stroke dirt bikes may have to come after a revival of the wider market.

What I want to get across to people now, which is about all there is to talk about, is the potential... what two-stroke engines can be - the future of two strokes. Whether one sticks such an engine in a dirt bike, a street bike, a lawnmower, or whatever, is an issue somewhat outside the realm that I will address. Within that realm, I must refer to a lot of things that are even outside the world of motorcycles, like the Skidoo. Because that is what we have or have had. Otherwise, I can only talk of theory, of thermodynamics, which most people won't understand, and which would leave me open to any and all contradicting theories.




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17th Nov 2008:
Let's get right to the question: What is wrong with the two-stroke engine? Nobody seems to dispute that the two-stroke is smaller, lighter, and cheaper to make than a four-stroke of equal performance. I think it has also been conclusively demonstrated that a high-performance four-stroke engine is more expensive to maintain. This is a very impressive list of advantages.

So what's wrong? Somebody is going to say that fuel consumption and exhaust emissions are too high. But wait! Is anybody screaming about the fuel consumption of Formula-One cars? Does anybody care about NOx emissions in NASCAR? Why is the racing two-stroke going away? A lot of people blame the government. But the "EPA ban" on two-strokes is a myth. The EPA has said over and over that their regulations can be met by four-stroke and fuel-injected two-stroke engines.

The problem is: there are no fuel-injected two-stroke motorcycle engines in production. (I'm ignoring a few "scooters".) So we have to look first at the fuel-injected two-stroke engines made for other applications, which could be adapted to motorcycles.

Let's skip over motocross and other closed-course racing that is run on private property - where (like NASCAR) anything goes. "Enduro" bikes may operate on public land, and the government does regulate what happens there. You should not be surprised to hear that a snowmobile operated on public land gets treated the same as a motorcycle. So, back in year-2000, the SAE (Society of Automotive Engineers) created the "SAE Clean Snowmobile Challenge", a competition to stimulate the development of cleaner snowmobiles. (Too bad they didn't choose motorcycles!) What happened? I am going to tell you why - technologically - the future of the two-stroke engine looks extremely bright!




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1st Dec 2008:
As expected, the CSC was a four-stroke affair. Nobody thought of building a "clean snowmobile" with a "dirty" two-stroke engine. But then, somebody always has to show off. After winning the CSC in 2002 and 2003 with a BMW, fuel-injected, four-stroke engine, the University of Idaho decided to do the unthinkable. The fact remained, they said, that "...avid snowmobile riders still prefer the lighter and more powerful two-stroke engine." They pointed out that a "simple" four-stroke snowmobile only made a little more than 50-hp. A high-tech, 750-cc with turbocharger and fuel injection made about 85-hp. The lighter Ski Doo, two-stroke, made 120-hp. So the UICSC team switched to a stinker. They won again in 2007.

What they did was adapt a direct-fuel-injection system (E-tec) from an Evinrude outboard motor. What you should appreciate is that everyone else in this competition was trying to get the best out of some four-stroke. And all the testing was done by engineers, based on EPA 2012 standards. No hype, no bias. The two-stroke won!

To put this into a dirt-bike perspective, a snowmobile is much heavier than a dirt bike - 500+ pounds. And the power transmission (a belt-track) is very inefficient (which is why they need so much power). So the snowmobile engine must work much harder, burn more fuel, and create higher exhaust emissions than a dirt bike, given the same use. If a two-stroke snowmobile is not a problem, a two-stroke dirt bike would be a party.

For 2009, there is the Ski Doo 600 E-tec (do a Google, and you will find pics and details). So let's imagine that we wanted to build a killer enduro bike. One half of that Ski Doo motor would give us a 300-cc, single-cylinder motor with 60-hp. It would have lower exhaust emissions and lower fuel consumption than any four-stroke of equal performance. And, of course, it would still be a simple, compact, light, easy-to-maintain two-stroke. All the real engineering has already been done - it works, the parts are in production.

If we went to Rotax, in Austria (Evinrude, Ski Doo, and Rotax are owned by Bombardier, in Canada), who builds the Ski Doo engine, and motorcycle engines, we could just tell them to take parts that they are already making and put them together into this killer enduro bike engine/transmission assembly. I'm sure they would be very happy to do this (for a nice chunk of money, of course). The UICSC team estimated that the cost of E-tec, for the twin-cylinder, would be about $300.

So what's wrong with the two-stroke? And where is the future of two strokes? Hold on, it gets better!




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15th Dec 2008:
To reiterate: Clean, efficient two-stroke engines (making 120-hp!) are in production and used in off-road vehicles on public lands subject to EPA regulations. Unfortunately, those "vehicles" are not motorcycles!

Let's look now at what Honda was doing just before they announced to the world, "No more two-strokes!" The story really begins a long time ago when people discovered that two-stroke engines would sometimes run without spark-ignition. That is, one could pull off the sparkplug lead, while the engine was running, and it would continue to run as if nothing had changed. People said, "It's dieseling." Actually, what was happening was very different from combustion in a diesel engine. The phenomenon was best explored by Shigeru Onishi in the 1970s. He called it "Active Thermo-Atmosphere Combustion (ATAC)." He said, "With ATAC the fuel consumption and exhaust emissions of two-stroke cycle, spark-ignition engines are remarkably improved, and noise and vibration are reduced." He eventually showed that a carbureted two-stroke engine could be more efficient (lower fuel consumption) than a diesel engine. But only within a narrow range of speed-load conditions.

In the 1990s, Honda R&D Chief Engineer, Yoichi Ishibashi, wanted to clean up two-stroke motorcycle engines. He called "ATAC": "Activated Radical (AR) combustion." Onishi`s engines ran generators at nearly a constant speed. Ishibashi needed to greatly extend the range where "AR" combustion was stable. He found that throttling the exhaust was the secret. He developed a 400-cc single-cylinder engine. For real-world testing, several of these "EXP-2" engines were put in endurance-racing chassis. They ran in the Granada-Dakar Rally and the Baja 1000. The results were good enough for Ishibashi to press on and develop the engine further.




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29th Dec 2008:
Two bikes were entered in the Dakar - both finished. As Ely Kumli reported in 1997: "The race results were very good even though the bike was not designed to win races, but to test new technology. When the dust settled, the EXP-2 had earned 5th overall and first in both the under-500cc and experimental classes..."

As it turned out, the second-string riders had been given the better equipment! "Compared to Honda`s NXR780 four-stroke twin rally race bike," said Kumli, "the EXP-2 has very similar performance, with several advantages. While the single-cylinder EXP-2 produces 54hp to the big NXR`s 71hp, they both make 58 lbs-ft of torque, but the EXP-2 is 118 pounds lighter giving it a slightly better power-to-weight ratio. What all this boils down to is that the EXP-2 has about the same real-world performance as the 780, but with substantially better fuel economy and lower emissions."

As good as that sounds, Ishibashi was just beginning. The exhaust valve prevented most of the fresh charge (fuel-air mixture) from getting lost out the exhaust port, but he needed to scavenge the cylinder with air only, and admit the fuel late in the cycle. He came up with a "pneumatic injection system" that used a standard four-stroke-type fuel injector. Ishibashi summarized the results: "...PDI-AR Combustion drastically decreases HC emission close to the level of four-stroke, and CO and NOx level is 1/5 and 1/7 of four-stroke level respectively. Furthermore, fuel consumption is improved 15% compared with the four-stroke." His English isn't perfect.

I will add: A Honda four-stroke engine giving equal performance had carbon monoxide emissions 500% higher and oxides of nitrogen emissions 700% higher than his two-stroke. Without an oxidizing catalyst, the two-stroke hydrocarbon emissions were slightly more than the four-stroke's, but with a cat, the levels of HC were the same. The CO levels dropped, but the two-strokes avantage over the four-stroke was actually greater. (NOx is unaffected by an oxidizing catalyst).

Obviously, Honda had a good engineer doing good work. He had one more song to sing before the bean-counters dropped the axe on him...




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[murf007]

part two

12th Jan 2009:
He did not begin with the long-stroke CR250, but with half of Honda's NSR500V. This was a case-reed road-racing engine with a square bore-stroke ratio - like the McGrath generation YZ250s. Honda said that it made "135-plus horsepower" at 10,500 rpm; about 68-hp for a 250.

If ten-five makes it sound like all the power was on the top end, one rider called it a "torque monster" and said the power was "similar to an open-class motocrosser". This engine was introduced at the first 500 GP, 1996. I have given these details because there has been, at least, the suggestion that the long-stroke 250 two-stroke had reached some sort of a technological limit (at less than 50-hp) and that the 450 four-stroke was some sort of a 'solution' to this 'problem'. In 2005, MotoVerde magazine (Spain) dyno tested the CRF450 and the RMZ450 and got 56-hp and 55.2-hp, respectively.

So this was the basis of Ishibashis new "environmental conscious power unit". But he really only used the parameters; he built a new design. He got "AR Combustion" to work from about 3000 rpm to peak power - meaning that the engine could operate normally within that range without an ignition system! At the very bottom, the sparkplug initiated combustion and his "Pneumatic Direct Injection" limited HC and CO emissions. The engine made 60-hp at 11,000 rpm.

Because the solenoid injector fed an anti-chamber - not the cylinder - its high-frequency limit did not restrict high-end power. In other words, Ishibashis approach did not require the invention of any new technology, only basic engineering. The technology required existed in the 1970s.

There was a rumor that the NSR500V might be turned into a killer street bike. Of course, that never happened. Instead, Ishibashi was sent off to design Civic door latches, or whatever...




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27th Jan 2009:
About now, someone should be asking: "If Honda knew how to make two-strokes that are cleaner and more economical than their four-strokes, that do not require any new technology, and that could win endurance races, why didn't they produce them?"

Back in 1984, Steve Anderson (then Technical Editor of Cycle World Magazine) went to Japan for a VIP tour of Honda's (then) new racing R&D facility. There, Takeo Fukui, Design Director, "...made it clear that Honda views itself as a four-stroke company that will not be satisfied until it wins all of its championships with four-strokes." Simply put, the four-stroke engine has been company policy; in fact, it has been more of a religion. Anderson saw, "...shelf after shelf of oval pistons..." and was told that engines were running "...with at least eight valves per cylinder..." and turbo charging. We haven`t heard anything about oval pistons in a long time because, after spending umpteen millions of dollars, somebody saw that it was a really stupid idea. It was a way of getting around the racing rules. Four-strokes couldn't win within the rules, so Honda had to find some way to beat the two-strokes and/or the rules. The trouble was, no matter what the shape of the pistons, or how many valves they could stuff in, or how many rpm they could get out of them, the two-strokes kept getting faster and the four-strokes weren't even able to keep pace. In 1995, Mick Doohan was asked how much power his NSR500 two-stroke made: "I can`t tell you that, but I can tell you that if Honda produced a one-liter motor it would make upwards of 400 horsepower."

It was about that time, it seems, when one of the four-stroke monks had an epiphany: "Instead of spending more money on exotic engines," he might have said, "which hasn't been getting us anywhere, why don't we just buy the AMA and FIM and make our own rules? For instance, we could require that all two-stroke riders wear their helmets backward - if they can't find the first turn, we have to win!" And that is - sort of -- what happened.

Honda also likes to be seen as an "engineering company." I must point out that trying to force a particular technology (that is not working!) on a naive public (by denying options, rewriting race rules, etc.) is not any sort of 'engineering.' Jeremy McGrath defined the engineer's job: "I think the effort should be to build the best bike, period, no matter what it is." Thank you, Jeremy.




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10th Feb 2009:
So, what is the 'best bike'? What does that mean - and who decides? Honda said, "No more two-strokes!" All over the world, riders dumped their two-strokes and rushed to buy four-strokes.

Back in the 1950's, a few intellectuals, like J.K. Galbraith, issued a warning. As George F. Will put it: "...Americans are a bovine, manipulable herd - putty in the hands of advertisers who can manufacture demand for whatever products manufacturers want to produce." As L.J.K. Setright put it: "If a camel is a horse designed by a committee, then it is the job of the public-relations and advertising men to persuade the customers that the camel is really a horse after all, or that what they really wanted was a camel." Do you know what you want? For the manufacturers, the 'best bike' is the one that gets you to part with the most money. As E.F. Schumacher told us... in economics, the only measure of 'good' is profit. I tell people that in engineering, goodness is efficiency. The two are opposites: profit leads to more and more; efficiency to less and less.

For you and me, 'best bike' must mean something else. What we are trying to do here is to give riders more information so that you can decide what the 'best bike' is for you. I don't want my fellow riders to get sucked-in the next time somebody says, "Da hump is a new feature, and next year we'll have a model with two humps!" If the manufacturers succeed by such deceptions, I too will end up riding a camel, because there won't be any more horses! I already know that the 'best bike' for me is the one not being made.

What I will try to do in the next few segments is to look at this notion of the 'best bike' and point out how much the aim depends on you - the individual rider. I will also point to the dirt bikes available today and stress how limited our options are. Where I am going, in the long run, is in the direction of answering this question: If the two-stroke engine has a future in our field of interest, what sort of dirt bikes might we see and how might these new options bring you closer to your 'best bike'?

I will begin by recommending a particular model, available now. I will put this in the form of a two-stroke/four-stroke comparison. I think the contrast is surprising. This bike could be an arrow pointing to much better dirt bikes in the future - if riders can get past their 'herd instincts'.

The future of two strokes continues...




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23rd Feb 2009:
The antagonist in my little play is Suzuki's RMZE 250. It says "Enduro Racing" on the swingarm. This is the motocrosser with minimum chassis changes to qualify as an "enduro" model. There is no electric starter or other non-essential to add weight. It weighs 229 lbs - less gas. It has five speeds and makes 33.4 hp @ 11.250 rpm. (All numbers in this comparison are from 'MotoVerde' magazine tests, not maker's claims.)

The protagonist (drum roll, please) is the KTM 105 JMC. (I will explain the odd suffix.) This little 105-cc wonder rips 30.5 hp @ 12,000 rpm and has six speeds. But what makes it fly is that the all-up weight, less gas, is under 155 pounds! No, that is not a misprint; Suzy weighs 75 pounds more.

Do this: Go out to the garage and find something that weighs about 75 lbs - a washing machine maybe. Pick it up. Do you really want to take that riding with you?

Let me interrupt this for a brief trip through the Way-Back machine. In 1980, the AMA dropped the "claiming rule" and the factories gave their top riders unlimited "works" bikes. Dave Hawkins wrote then: "In motocross racing, it's obvious that power is important. But how much is enough?" In the 125 class: "The problem was not to make more power (30 bhp seemed quite enough for a 175-pound bike)... [and] only the best can fully use these bikes." Today, 30 years later, we still can't go into a dealer and buy a 175-pound bike with 30 hp. Instead, we are expected to dance with Miss Piggy from Hamatsu. What we can do is buy a 105 SX and bring it up to that old works-bike standard. And unless you are a better rider than the likes of Jeff Ward, Mark Barnett, and Broc Glover, that should be "quite enough".

Let's get into the details. First, what is JMC? That is the establishment (in Spain) of Jess Balaguer. I cannot avoid calling him one of the top two-stroke tuners in the world. He has "the gift". He tweaked more than a 50% increase in horsepower from KTM's standard 105 SX. But that statement will make you think that it must be all top-end and could only make noise below ten-grand. In fact, the JMC is stronger everywhere. The smallest percentage increase is at 6000 rpm, where it still makes two ponies more than stock. And the stock motor is in no way peaky; it actually makes less peak power than the 85 SX. The 105 is more of an "enduro" motor. The JMC pulled the 'MotoVerde' dyno from 3000 rpm to 13,500 rpm. I cannot point to another engine that makes almost 300 hp/liter and has such a wide powerband. And while dynos can give one the wrong impression, the 'MotoVerde' crew said that the track tests confirmed "without a doubt" what the dyno promised. The bike rockets out of turns like...a works bike!



What Are Your Thoughts On The Future Of Two Strokes?

 

[sharky243]

I am guilty of falling victim to the 4-stroke frenzy, but I still love the raw power of a 2-stroke. There is something about a 2-stroke's power, and the best 4-stroke in the world can't beat it !! I am currently restoring my 1996 YZ 250, and I can't wait to throw a leg over it again and twist the throttle.
LONG LIVE THE 2-STROKE !!!!!!

 

[2strokesrock]

I recently saw a post on here about the "NASCAR" inspired dyno they are useing to test dirtbikes now, and they said it cost over $100.000.00.
It won't be long before only the vary weathy can race motocross because of the extreamly expensive 4 strokes, just like NASCAR.

 

[murf007]

Coming Soon? KTM Fuel Injected Two Stroke
By The General • on February 15, 2009




It appears that KTM has Fuel Injection ready for two stroke motocross bikes. In the August 2008 issue of Motocross Digital magazine (free subscription available at http://www.motocrossdigital.com/ ) was the following blurb about the KTM effort.

The 250SX could have a bright future, it depends on what happens regarding the rules and regulations: KTM wants them to be introduced to MX2 to allow teams that don’t have millionaire budget to compete against the 4-strokes. For the 2-stroke, the injection is ready, and this would provide cleaner and precise power delivery.

While the idea of fuel injection for two-strokes has been talked about and discussed, there has been little to indicate that it would be workable on a racing two-stroke motocross bike. This news points to the fact that KTM has been working on it for quite some time and seems to have solved the issues that prevented fuel injection for racing two-strokes.

Since this article in Motocross Digital was written some changes have been announced in the FIM rules to allow two-strokes to compete with four-strokes in MX2 (250cc). There are also rumblings that this rule will be applied to the AMA Outdoor Nationals for 2009.

So there is a good chance the Fuel Injected 250SX KTM will be hitting the tracks in the very near future. This is great news for all the two stroke fans of the world.

Two thumbs up for the folks at KTM!

 

[smahala1286]

I know this is an old thread but has anyone heard anymore info on KTM producing a fuel injected 250sx?

 

[Tharrell]

bump. Anybody?

 

[helio lucas]

http://www.dirtrider.net/forums3/showthread.php?t=154020

while the text is a great read is not that simple.we can just not convert a steady speed boat or snow mobile engine to a dirt bike. please keep in mind this have been tryed several times from major manufactures. it takes bimota to bankruptcy.
but from now, we already have indirect fuel injection on 250 mx bikes... now just get the injector to spray twice as fast than on the rmz, with much more pressure to spray directly on the combustion chamber and it´s done.
at 15k rpm a four stroke may have some 0.004s to spray while a DI 2ST may have 0.00078s...

if it´s done would you buy it?

 

[julien_d]

What's the lure of fuel injection for a 2 stroke? Maybe I don't understand. You have an added level of complexity and more electronics to fail for a minimal ROI. A true 3 circuit carb will have the same benefits with a lot less complexity.

I think what we really need to see with a 2 stroke race engine is oil injection, and a simple method of separating exhaust gasses from intake charge during scavenging without sacrificing the performance offered by a tuned pipe. Husky found a simple way to do this with one of their new chainsaw engines using an additional intake port and transfer port to pull in fresh air as a buffer between the exhaust gas and intake charge. Others are doing this by using forced air and a cam driven exhaust valve which closes the exhaust port (blech). I can't really care for the idea of a camshaft in my 2t either.

 

[Pete Payne]

Now that is a good read!

 

[SVTMc-G]

That WAS a great read. no matter what...either way....I'm sticking with my stinky smoker. Nothing better than the smell of my two stroke on a cool 50 degree, dewey morning. better than the smell of fresh coffee, donuts, and newspaper!