Motorcycles

KTM announces new fuel injected two-stroke Enduro range

KTM announces new fuel injecte...
KTM has released a sketch of its new two-stroke engine for the 2018 25-0 and 300 EXC TPI Enduro motorcycles
KTM has released a sketch of its new two-stroke engine for the 2018 25-0 and 300 EXC TPI Enduro motorcycles
View 2 Images
Current KTM two-strokes, like the 300 EXC, rely on good old tech - Reed valves and Mikuni carbs - that will find it very hard to survive under stricter Euro 4 emissions rules
1/2
Current KTM two-strokes, like the 300 EXC, rely on good old tech - Reed valves and Mikuni carbs - that will find it very hard to survive under stricter Euro 4 emissions rules
KTM has released a sketch of its new two-stroke engine for the 2018 25-0 and 300 EXC TPI Enduro motorcycles
2/2
KTM has released a sketch of its new two-stroke engine for the 2018 25-0 and 300 EXC TPI Enduro motorcycles

In the chronicles of motorcycling, the year 2017 will be remembered as the point in time when Euro 4 emission laws came fully into effect in the European Union. In this environment it is indeed quite strange to hear that a major manufacturer is developing a new two-stroke engine, yet KTM is doing exactly that for its Enduro motorcycles. And it could well prove to be a game changer.

Ever since the 1990s, two-stroke motorcycles have gradually vanished from mass production, with the only exceptions being off road machines or very small commuters. Several manufacturers – mostly Europeans, like KTM, Husqvarna, Beta, and Gas Gas – still retain a core lineup of two-stroke Enduro and Motocross models, but these are usually old school designs, modernized as much as carburetor-fed engines can be. Chances are that most of these will have a very hard time squeezing into the Euro 4 mold.

There's little doubt that modern technology could have come up with clean two-stroke engines years ago. Honda almost proved it in 1995 with its Activated Radical Combustion tech, before unexpectedly scrapping it. The following decade saw the rise of direction injection systems for two-stroke engines, but this tech would remain limited to outboard engines and snowmobiles. For motorcycles, it seems that the decision to drop two-strokes was political, rather than scientific.

Rumors regarding the development of new two-stroke motors with direct injection started spreading again around 2012, with several manufacturers said to be working in this area. Among them was KTM, a company that made its name with two-stroke racing machines. Apparently, the time has now come for the new generation to hit the market.

KTM is getting ready to unveil its new engine in May, using it to power two 2018 Enduro models, 250 and 300 EXC TPI, where the initials TPI translate as Transfer Port Injection. This is the key tech that allows the new engine to offer widespread power delivery and fuel efficiency, all the while conforming to tight emissions rules.

By adding direct injection right in the transfer port of the cylinder, the amount of fuel can be strictly regulated and controlled by the engine's electronic brain. In similar fashion, lubrication is expected to be handled with equal accuracy, resulting in an engine freed from the ailments that branded two-strokes as dirty.

Current KTM two-strokes, like the 300 EXC, rely on good old tech - Reed valves and Mikuni carbs - that will find it very hard to survive under stricter Euro 4 emissions rules
Current KTM two-strokes, like the 300 EXC, rely on good old tech - Reed valves and Mikuni carbs - that will find it very hard to survive under stricter Euro 4 emissions rules

It is important to note that KTM is not just talking about new two-strokes, but centers in on Enduro models. Unlike motocross bikes, Enduro bikes have to be road-legal even in racing guise. KTM's announcement implies that the new models will have no problem conforming with Euro 4 rules, while at the same time remaining competitive enough for world championship-level racing.

The new motor has been in development for several years, and KTM field tested a couple of prototypes at the Roof of Africa hard Enduro race in Lesotho, that took place last December. KTM product marketing manager, Joachim Sauer, revealed in an interview with Enduro Illustrated from last July that the two-strokes return better fuel efficiency than the current race-winning 350 EXC-F four-stroke. He also insisted that they run clean under all circumstances, performing ideally even in very cold starts, and produce a broad powerband that would make it difficult for someone to tell the difference between the two and the four-stroke model.

There is of course a downside. The new two-stroke technology will make the new bikes quite expensive, with Sauer expecting a price tag directly comparable with the class-leading four-strokes.

KTM says that the new 250 and 300 EXC TPI will be unveiled on May 15, and are expected in European markets in the following months. A very limited quantity will head over to USA and Canada towards the fall (North Hemisphere) of 2017.

What will be even more interesting though, is how this move will resonate with KTM's competitors. If there are other companies secretly working on modern two-stroke technology as rumored, this would be the time to come forward.

Clean, problem-free two-strokes that can produce amounts of power that no four-stroke can, combined with strict emissions compliance, wide power delivery, and all the maintenance gains from not having a complex cylinder head assembly? Sounds like a whole new world of possibilities.

Source: KTM

10 comments
10 comments
JimFox
Well, I'm dumbstruck! All the decades 2-strokes were produced they were noisy, stinking polluters. Now this? Hard to believe. Downside- that it may delay or inhibit electric bikes, which IS the future.
guzmanchinky
Noise. That's the number one reason trails are being closed all over the world. We need completely quiet as possible 4 strokes, and eventually electric machines. Not 2 strokes.
Buellrider
Clean burning 2 strokes is smarter than 4 stroke complexity. I'd give it a spin.
Bob B
I've been wondering when other companies would upgrade two stroke technology in the same manner that Bombardier did years ago. In the outboard motor market, the E-Tec two strokes have as good or better emissions than comparable four stroke engines. They are also very quiet in operation, although the quietest four strokes probably still win that contest. Bombardier also uses the E-Tec technology in snowmobiles and perhaps some other toys, but I'm not sure if they've put it in any motorcycles yet.
DavidRogerBrown
Many of us ageing baby boomers started out on 2-stroke dirt bikes. One would never have thought we would see a street model again. Will be very interesting to see a comparison with a 300 EXC. KTM makes nothing but top quality machines. Until there is a battery break thru,electrics will of all vehicles remain marginal.
zr2s10
If they keep adding all of this, eventually the 2 stroke won't have any maintenance advantage over 4 strokes. I could see this being good for racers wanting more power, but they'll have to be displacement specific because of classes. 2 strokes can be fun, especially in the dunes or other wide open stretches. Trail riding is definitely 4 stroke territory. Even high power ones can last a long time with proper maintenance, and the power delivery is much more manageable for technical riding (rock crawling, etc). Noise is definitely a concern, but around W. Pa at least, the main loss of trails is lawsuit concerns. Most people I talk to that post their land, do so because they don't want to get sued if someone wrecks on their property. Another one (probably a tie) is property damage. A lot of timber companies (and gas/oil/coal companies) are buying up the biggest plots, and they don't want anyone damaging future profits, or suing them. It used to be that you could connect lots of small trails by using old abandoned rail lines, but Rail to "Trails" has taken over almost all of them, and they're not interested in "shared use". But of course, noise does come into concern, which is why most of these trails would never have been allowed to become OHV trails if we had pushed for that. And no, electric isn't the way to go on these. Fuel injected 4-stroke gas or diesel is best for off-road machines. When I go out, I'm out most of the day, since I can't get out very often. I'm not cool with running out of juice, with no way to charge. Since they're not gonna make "hot swap" setups for people to do changes on the trail with 100V or higher batteries, range is very much an issue. I also don't want a high voltage system on my trail machine. But maybe I'm just not educated enough, right?
Martin Hone
Interesting that no mention was made of the Orbital technology, which used compressed air to blast the fuel into superfine droplets directly into the combustion chamber. I know the technology was sold to Suzuki and a number of outboard manufacturers, so maybe it survives in the marine industry. Certainly ahead of Honda's attempt.
Daishi
@zr2s10 weight can be kind of a huge issue on dirtbikes. You come along a couple of trees fallen over your trail and you have to dead lift your bike up over the log. It depends on how groomed the trails are that you ride on or if you just kind of explore unkept trails through the woods but heavy bikes are a pain to lift wearing gear on a hot day. This is why I'm such a fan of little 250 cc dual sports, the bigger "adventure" bikes are completely out of the question for this use unless you are The Mountain from Game of Thrones.
PaulYak
In the 1980s I was so excited to hear of the "Orbital 2 stroke engine", it also promised greater fuel efficiency, nice wide powerband and simple design. Ford bought it and shelved it.
I hope KTM can achieve, what I believe will be an amazing power source for the motorcycle market.
Paul Muad'Dib
In motocross 4 strokes are used because of the rules, if the restrictions were lifted the field would be dominated by 2 stroke bikes again. I’m not sure but if I had to guess I would say in Enduro there are no restrictions on the engine like there are in motocross.