Why did KTM make a fuel-injected two-stroke in the first place? Was it to make their customers happy? Did the market demand one? Would it make the bike lighter or faster? The answer is, none of the above. KTM didn’t want to mass-produce a fuel-injected two-stroke, but they had to have one in their back pocket for when the time came that they had to have one. What time? We will get to that in a bit. KTM and its blood brother Husky sell more carbureted two-stroke engines than they do any four-stroke engine. Plus, they don’t have any competition‚ other than used Craigslist YZ250s. So, for them to dump oodles of dough into developing a new bike, there must be something big on the horizon that scares even the orange juggernaut.


Environmentalists. If that word gets you heated like it does us, don’t let anyone tell you that you don’t care about the environment just because you ride an offroad motorcycle. You dispose of used oil properly. You recycle your old tires in a sensible manner. You salvage old two-strokes to keep them out of landfills (and back on the track where they belong). You enjoy the beauty of nature (and actually spend time outdoors). Environmentalists think that anyone who does anything, apart from complain, is the mortal enemy of the planet. They can take things too far. If it’s hot, it’s global warming. If it rains, it’s global warming. If there are hurricanes in Florida, it’s global warming. If there aren’t hurricanes in Florida, it’s global warming. Global warming might play a part in some of these, but have you ever noticed that when the weatherman says that this is the hottest day on record, he always adds, “Since 1974.” Makes you wonder what was happening in ’74.

Euro4 is the name of the legislation that puts a limit on the emission of pollutants by new vehicles in Europe. It all started in 1999 when the Euro1 came out, followed by Euro2 and Euro3. Then, in 2016, Euro4 was introduced, and it forced KTM and Husky to bench their offroad 125 bikes. With each passing of new Euro1, 2, 3 and 4 emission standards, the tests got tougher to pass, especially for small-displacement bikes. That’s not all. In 2020, Euro5 is coming.

So what does Euro4 have to do with the United States? That’s simple, Euro4 is Abbott to the EPA’s Costello. As for now, your trusty-but-rusty dirt bike is safe from excessive EPA regulations. And, paradoxically, that is bad news for KTM. How so? If KTM has to make a special two-stroke offroad bike for the European market only, they won’t make any money. They need to sell lots of bikes, which translates into selling bikes in the USA in order to get any kind of return on investment. European regulations will force offroad two-stroke riders in the European Union to go to fuel injection, but American two-stroke riders are a rare breed—and the EPA may have to pry their Mikuni TMX carbs out of their cold dead hands.


KTM has no choice. If they don’t meet Euro4 (and in a few years Euro5), they might as well stop making two-stroke offroad bikes altogether. The corollary of this is that if KTM loses the European market, then the return on investment in the American market may not be viable for full-blown production. It’s a catch-22.

MXA is a hardcore motocross magazine, and closed-course competition motorcycles are not bound by emission standards. They are small in number, ridden for very few miles in a year and not used on public lands. But, MXA traveled to Austria for the debut of the 2018 KTM 250XC-W TPI because this bike could be something big, something groundbreaking, something important and something special. It should be obvious that we were worried that the strict emission standards were going to suck the life out of an engine that is known to be the most powerful production 250cc engine the world has even seen. We wanted to see the future, and the best way to do that was to get our hands on the two-stroke of the future.


First, before we could see the future, we had to convince KTM that a motocross magazine should be invited to the unveiling of a fuel-injected enduro bike. They were up for it, and so managing editor Daryl Ecklund, a former AMA National rider, packed his gear and headed to the Iron Giant; you may know it better as the site of the Erzberg Rodeo offroad race. Erzberg is actually a wonderfully scenic part of Austria, with the exception of the enormous Erzberg strip mine, which has been worked since the 12th century. In fact, the word “Erzberg” translates into “Ore Mountain.” Every year 1500 riders start the Erzberg Rodeo, 500 riders qualify for the main event and only a handful of riders finish. Fun fact: in 2015, nobody finished the race. To settle the matter, a four-way tie was declared for first place between Jonny Walker, Graham Jarvis, Alfredo Gomez and Andreas Lettenbichler. Daryl Ecklund loved the idea of riding at Erzberg, because he split his Pro days racing motocross, EnduroCross and offroad while also working as a trainer for several offroad riders good enough to actually finish the race.



Before we get into riding the bike, we want to touch on how cleverly and elegantly KTM developed the bike. This was no overnight success. The R&D phase was a decade-long series of trials and tribulations, leading to the 2018 KTM 250XC-W TPI. Over that decade KTM tried every possibility for building a fuel-injected two-stroke—and that included direct injection. It wasn’t until they built a prototype that they realized that direct-injecting a two-stroke had too many compromises, including cylinder height, high fuel-pump pressures and excessive weight. The path to Transfer Port Injection (TPI) wasn’t smooth, but once they worked out the bugs, the system was clean, simple, light and affordable. With TPI, the KTM engineers were able to carry over the same dimensions and layout as the carburetor engine. The major changes between a carbureted KTM 250XC and the fuel-injected KTM 250XC-W TPI were two lateral domes that held the nozzle that injected fuel into the rear transfer ports with a small-diameter tube in the back of the cylinder connected to the intake pressure sensor.

If you ride a 250XC-W TPI, you can throw your Ratio-Rite away. Oh, the gasoline still needs oil mixed in for lubrication, but KTM borrowed a time-warp idea from the 1970s to get the job done. It used to be called “auto lube” on 1970s trail bikes—and it spritzed oil into the engine so that oil didn’t have to be mixed into the gasoline. You might not have to own a Ratio-Rite anymore, but the engine still requires oil to be mixed into the gas. KTM achieved this by mounting a 700cc oil tank under the backbone of the frame. The tank has a pulse oil pump mounted on it. This pump delivers oil to the throttle body using engine speed and throttle-position sensor data to mix with gas at an average 80:1 fuel-to-oil ratio. This average 80:1 ratio means you will have to fill up the oil tank every four or five tanks of gas. To fill the oil tank, there is a filler-cap assembly located between the fuel tank and steering head (a hose directs the oil back to the oil tube via the upper frame tube).

Lots of what makes the TPI-equipped bike work are the results of KTM’s Engine Management System (the brain of the bike). The black box makes everything work in unison (when it runs in unison). This system runs off a 196-watt generator. It determines the ignition timing and the amount of fuel to inject based on several senor readings such as intake and ambient air pressure, throttle position and oil and water temperature. The 250XC-W TPI also features an automatic altitude and temperature-compensation system, which essentially “jets” the bike automatically.

Transfer Port Injection (TPI) wasn’t easy to develop, but once they worked out the bugs, the system was clean, simple, light and affordable.
Transfer Port Injection (TPI) wasn’t easy to develop, but once they worked out the bugs, the system was clean, simple, light and affordable.


Once Daryl arrived in Erzberg, he was told the riders would be broken up in groups based on skill level. Daryl played it safe by signing up for the intermediate group of riders. That didn’t work for very long, because KTM’ North America’s David O’Conner ratted Daryl out by telling the assembled crowd, “Don’t let him fool you, he’s a former National Pro!” Daryl didn’t argue; he put his helmet on and lined up with three-time Erzberg champion Jonny Walker, who would be Daryl’s tour guide for the day.

It wasn’t the worst thing in the world to have one of the world’s great offroad riders taking you over hill and dale, especially since Jonny just happened to be one of the riders that Daryl worked with when he was a trainer. When Jonny saw Daryl walk over to his group, he said, “Don’t worry, Daryl, if you can’t make it up a hill, I’ll ride the bike up for you and you can just walk up.”

The oil filler cap is located behind the steering stem. In this cutaway photo you can see the tube that brings the oil through the frame to the 700cc oil tank.
The oil filler cap is located behind the steering stem. In this cutaway photo you can see the tube that brings the oil through the frame to the 700cc oil tank.

Like old trail-riding buddies, Jonny and Daryl played cat and mouse on the fast motocross-style part of the Iron Giant. Rolling on the power, Daryl could feel that the KTM 250XC-W TPI bike was no slouch. In tight corners the throttle response was instant, but it wasn’t easy to find the right gear to get back into the meat of the powerband. At the first big hill Daryl stayed in Jonny’s shadow, who was on KTM’s 300EXC TPI (which will, not be imported to the USA until 2019), as they snaked their way up a difficult climb. Daryl’s ascent was going just fine until he hit the top end of the power range and he started to wheelie, almost looping out part way up the hill. Trying to shake the rust off, he watched two of the other riders in the fast group loop out on the hill.

After the fast group all made it to the top of the hill, Jonny led the group on some tight singletrack. The 250XC-W TPI felt like it was between gears on the tight stuff. Second gear was jerky and put too much weight on the front end, while third gear couldn’t get out of its own way. Daryl had to abuse the clutch to keep the rpm up. It ran very odd at low rpm before hitting hard and taking off from the mid on up. It was boggy down low and rip-roaring fast on the top. There is no doubt that this is a mapping issues that can be solved at the factory. The good news was that the bike wouldn’t stall. You could start from a dead stop and put the bike in sixth gear and still manage not to stall it. It was awesome. Once one guy tried riding in an ultra-tall gear, everybody in the group tried it and was amazed.

KTM’s first attempt at fuel injection was to try to direct injection into the combustion chamber. This is the first prototype engine, but it was too tall and heavy for the job.
KTM’s first attempt at fuel injection was to try to direct injection into the combustion chamber. This is the first prototype engine, but it was too tall and heavy for the job.

Once the trail opened up, it was possible to test the top-end power of the EFI smoker. It took a while to get the bike going and into the meat of the power. Towards the top of the midrange, a big surge of power would hit abruptly. It wasn’t uncontrollable power, but it was too much at the wrong time for offroad riding. When wringing the 250XC-W TPI out, it gave the impression that it was on the rich side, as though the bike wouldn’t totally clean out, but it stayed consistent across 2000 feet of elevation change.

When the group came to the last hill on the first test ride, Daryl was dragging his tongue at the back of the pack (too much typing and not enough riding). At the top of the hill the top-end hit caught him off guard, and the bike looped out from under him in front of the whole group. True to his threat from that morning, Jonny casually picked up the bike and finished the rest of the climb with ease.

After some lunch, the group went out again. This time Daryl was on the Euro-only KTM 300EXC TPI. The same fast motocross-style trail led to the big hills, singletrack and finishing loop. It made for a good comparison between the two bikes. Daryl noticed the 300 revved out faster than the 250XC-W TPI model, but not by much. In the tight corners a flick to the clutch would get the power right where it needed to be. The powerband reminded Daryl of the Husky TX300 that MXA converted into a motocross bike. Up that first difficult hill the 300’s power was right where it needed to be at all times. It was confidence-inspiring. It had the power you needed when you needed it. The rear end tracked similar to a four-stroke. In the tight trails, where second gear was used on the 250, Daryl managed to use third gear all the time and even pull fourth in some sections. The more generous midrange power allowed the bike to be ridden in a higher gear. This made the bike feel nimble, manageable and easier to ride. It felt exactly like a carbureted bike, exactly like MXA’s TX300.

MXA rode both the 250cc and 300cc fuel-injected KTMs at Erzberg, but the 300 won’t be coming to America in 2018.
MXA rode both the 250cc and 300cc fuel-injected KTMs at Erzberg, but the 300 won’t be coming to America in 2018.

We don’t even have to mention the hydraulic clutch, electric starter, superb braking and no-tools airbox—they are a given on a KTM. We don’t want to sound harsh about the KTM 250XC-W TPI. It really is an amazing feat to build a fuel-injected two-stroke. Not just one that ran, but one that could pass strict emission standards. KTM is the first of the “Big Six” to market a Transfer Port Injection machine that is close to a tried-and-true carbureted bikes. The 250XC-W TPI has the potential to be as good as the 300 TPI. Why? Because the 250 TPI and 300 TPI operate off the exact same running gear, injector nozzles, ECUs and cylinder design. They are spitting images of each other, save for the bigger piston.

With a little work on the ECU mapping, power-valve settings and gearing, the 250XC-W TPI could easily be brought around to run like the 300EXC TPI. We are pretty sure that KTM will iron out the bugs on Daryl’s 250 before it hits the American shores. At Erzberg, there was no time to make the changes needed, so the MXA wrecking crew looks forward to getting our hands on this  bike in the near future. Kudos, KTM, on breaking the mold once again, because achievements like this have made KTM the juggernaut they are today.

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