This article was originally featured in the August 2017 print edition of Dirt Rider
Two-stroke and fuel-injection lovers, the big day has come! KTM’s 250 XC-W TPI is here. And to show the orange engineers weren’t afraid to throw this bike (and a handful of magazine test riders) at some of the toughest riding on earth, the bike intro was held at the home of the most extreme off-road competition: Erzberg!
KTM has spent more than 10 years developing two-stroke EFI technology for the off-road market because it knew the importance of the bike working perfectly before it was released into consumers’ hands. Well, Big Orange achieved it—the FI two-stroke engine is awesome.
The company has a 250 XC-W TPI that will be available in the United States this fall. Also, in addition to the 250 XC-W TPI, 250 and 300 EXC TPI models are available in Europe as 2018 models. Let’s keep our fingers crossed that KTM makes a 300 XC-W TPI available in the United States for 2019…or a 2018.5 model.
The KTM 250 XC-W TPI system starts with the powerful and proven counterbalanced 250cc two-stroke engine. After years of two-stroke FI development, KTM found good performance, reliability, and (significant in Europe) the ability to meet Euro 4 emission standards with the patented “Transfer Port Injection” (TPI). The system starts with a 39mm Dell’Orto throttle body equipped with an idle adjusting screw and a separate cold-start device that opens a bypass to allow in extra air. Oil is supplied from the automatic oil pump and injected through the throttle body with the incoming air. The Dell’Orto throttle body does not house a fuel injector, as KTM found mounting two fuel injectors downstream into the rear transfer ports provides excellent atomization of the fuel with upstream air. The result is highly efficient combustion and reduced losses of unburned fuel.
Knowing when and how much fuel to inject is all controlled by KTM’s engine management system (EMS). This system uses a newly developed electronic control unit along with five sensors that determine not only how much fuel but also how much oil to inject. You will recognize these sensors as: throttle position, coolant temperature, intake air temperature, intake air pressure, and ambient air pressure. Thanks to these sensors and the EMS, there is no longer the need to manually adjust the jetting for temperature or altitude conditions.
The 2018 250 XC-W TPI comes with a six-speed wide-ratio transmission, electric starter, lithium-ion battery, and a more powerful generator to meet the requirements of the upgraded EMS. Built into the EMS is the option to mount an accessory radiator fan from the KTM Power Parts catalog that is controlled by the engine management system. We started our day at Erzberg at about 2,700 feet above sea level and headed straight into some tight woods. I was surprised our KTM guide left us little time for the bikes to warm up. However, they ran perfectly after only a minute or two of idling while I strapped on my helmet and pulled on my gloves.
These trails were quite tight, and if this was my personal bike, I might want to cut down the bar 10mm on each end just to give me a little bit of extra clearance. On the plus side, KTM has some of the best hand guards on the market, and I certainly put them to the test. I was not sure what to expect from the engine, as normally FI makes an engine feel a little smoother. I did feel like this bike was just a little flat off the bottom. There were areas where the wide-ratio transmission kind of made me want a slightly taller first gear or maybe a slightly lower second. In the tight stuff, I mainly left the transmission in second and used the clutch more. This was not a problem, as KTM’s hydraulic clutch is bulletproof. As much as I used it, the clutch never changed its feel or hook-up.
From there we began to climb some steep hills with fun switchbacks. I was impressed by how easy it was to turn this bike up the hills. The TPI engine’s ability to run at an unusually low rpm made navigating some very tight switchback turns easy. Another great feature of the low rpm was stopping and starting on a hill. When you would normally think you were stuck or maybe had to roll backward, you could just sit back to get a little extra weight on the rear tire and lug the engine up the hill. Wheelspin was very controllable. Also impressive in the tight woods was how this engine continually seemed to run at low temperature. Our slower pace in the tight woods did not allow for much airflow through the radiators, but at no point did the bike seem to be overheating. I am confident if I had ridden a 250 four-stroke, the coolant would have been boiling.
We popped out of the woods a few hundred feet above our starting point onto a road leading into our first hill climb—Erzberg’s Water Pipe. This was certainly a big climb, but there was no reason to not make it. On my first attempt, I approached the hill a little cautiously in second gear. At about the halfway mark I was thinking I picked too low of a gear, as I thought I might run out of rpm. I just kept the throttle pinned and this bike really surprised me at how well and how far it revved. It pulled me up no problem. We spent a little more time climbing Water Pipe, and I tried it in third and even fourth gear; third was definitely preferred for this hill. We used a fairly steep section to descend between climbs, and I felt very comfortable with the chassis. The bike is well balanced and stable, and it gave me confidence even as the environment and obstacles tried to take my confidence away. Letting the KTM free-wheel was not an issue, and when I was beginning to go a little too fast, KTM’s 260mm Brembo front brake was there to slow me down.
From there we headed into flowing trails lined with tree roots and smaller rocks. Standing up and pushing my pace in the woods was easy. The engine felt better in these trails, as we were mostly in second and third gear. The KTM WP Xplor 48mm fork soaked up the rocks and still had good hold-up when I was hard on the brakes. Accelerating over the roots and rocks was comfortable, as the WP Xplor PDS shock soaked it up with very little negative feedback.
These trails opened up into an area where KTM laid out a little bit of a fun moto “special test” section. This was not a motocross track; it was more of an open area single-track with some small rolling mounds where I could feel a little more of the suspension action. Keep in mind we are in the middle of an iron ore mine—they don’t have much in the way of fun, fast, sand whoop sections. I did notice in some of these “special tests” sections the suspension was a little soft and would have benefitted from a little more control. This moto section also exposed a little bit of a flat spot in the engine if the rpm isn’t kept up. And for those times when you want to ride it a little more aggressively, the engine could use a little more roll-on torque off the bottom.
KTM laid out a fun course through a rock garden that was maybe a quarter-mile long. The rocks varied in size from bowling ball to medicine ball. I would say this is one of the sections where the bike really shined. I entered in second gear and only had to use the clutch to carry the front wheel in a few spots. The fork dealt with the sharp-edged rocks without deflection, and the rear wheel followed right along without bouncing out sideways. KTM engineers have the chassis dialed for these types of conditions. The next special test section, Dynamite, was set up for us as a down and back. Just dropping into Dynamite was intimidating. I was really getting comfortable on the KTM 250 XC-W TPI; Dynamite was certainly challenging, but the bike definitely made it easier, as it was in its element.
We visited a few other famous sections like Machine and then Carl’s Diner. I think we could have attempted these, but then again I might still be there today trying to make it up, and I knew KTM wanted the bike back at the end of the day. We continued to the summit of the mountain for a quick break, a drink of water, and a few photos. Before we began heading down, I started to think about how well this bike was running. Normally, a two-stroke engine is more affected by changes in altitude than a four-stroke. I would say that at 3,500-plus feet of elevation, a typical two-stroke can benefit from some carburetor adjustments and the problems will become even more noticeable every 1,000 feet from there. The EMS was doing its job the entire way, and as much as I would let the bike idle or lug it, there was no need to clean it out with a quick twist of throttle. Naturally, the engine did lose a little power as we approached the summit (which is expected regardless if you have a two- or four-stroke), but it was not even close to as much as what I expected.
Just when we thought the adventure was over our guide informed us we were going down Elevator. Once again I was glad the 250 XC-W TPI was easy to ride. The brakes were good and the suspension was very forgiving. These were some of the steepest, rockiest, longest downhill switchbacks I have ever ridden.
At the end of the day I’d ridden this bike for about five hours and climbed from 2,700 to 4,700 feet and back down. At no point did the TPI system do anything but run flawlessly. The bike never overheated during the 75-degree day. I abused the clutch and it never faded, and as it hit huge rocks the pipe was still in perfect shape. I would say this is a big step in bridging some of the gaps between two-stroke and four-stroke motorcycles. KTM’s hard work has helped improve several of the two-stroke weaknesses. It gave up little to none of the two-stroke benefits and integrated some of the features I like about the four-strokes. This stock bike managed the Iron Giant really well.
As for Erzberg, it was eye-opening. I enjoy riding and racing and enjoy a challenge. I have a newfound respect for the riders who finish the Erzberg Rodeo. It’s on my list of top five places I would like to return to, but as for racing there, no way. Trust me when I say that place is no joke.
- No need to jet the bike or mix oil
- Consistent feel of the engine and throttle response regardless of altitude
- Very easy, light, and nimble to ride in tight trails
- No need to carry premix oil on long weekend rides with gas station fill-ups
- Engine is a little flat off the bottom
- Suspension is a little soft on bigger hits
- The 300 isn’t coming to America this year