The KTM SX Series 2023 Review
KTM is the brand with their finger on the pulse when it comes to two-stroke demand. Like several other brands on the market (Beta, Sherco, Yamaha and other brands under the KTM umbrella), they saw an unwavering desire for two-stroke bikes across the country. News broke about the new fuel injection technology for the full line of two-stroke KTM and the Orange Brigade debuted their new bike at the recent launch of the 2023 model.
The bikes we ride at RedBull aren’t exactly the same bikes you’d buy off the showroom floor. This pumpkin was in the final stages of its development when we got it. In fact, fuel injection engineers from Austria were on track to take feedback on the system they designed. The new 125, 250 and 300 SX models are available in the media while the XC models, which will also have the same fuel injection technology, will appear in the United States later this year.
Read any comment thread on social media and you will see a request for two strokes. Riders filled with nostalgia of today and of the past can’t help but reminisce on the glory days when the sweet scent of premix filled the air. Sights, sounds and smells can be recognized by any rider. But for better or for worse, times have changed, and four strokes dominate the modern motocross scene. That’s not to say that two strokes are unpopular. Take a look at any enduro or cross country race and you’ll find most of the podium spots are filled by riders with two strokes.
While we only got about five laps on each bike during our day at RedBull, it’s easy to see the future of two-stroke technology is in good hands. Again, this new KTM is still in the final stages of pre-production, and apart from the suspension setup, it’s hard to tell the difference. The new chassis, bodywork and rider cockpit are barely noticed as everyone is talking about the new engine, but these changes all feel familiar and comfortable after riding the new four-stroke model. Fuel injection is certainly a step forward for premix lovers. We see it as an advantage because of its ease of use and reduction of jetting headaches. This bike will perform at any height and offers a similar feel to the old trusty carburetor engine. In the end, we’re very impressed with the KTM 2023 two-stroke model and are excited to combine some fuel and spin more laps in the future.
TPI vs EFI system
If you’re like me, you’re probably thinking, “I think KTM is already using fuel injection on their two strokes.” That’s right, well, sort of. Enduro bikes from KTM and Husqvarna previously featured TPI, or Transfer Port Injection. This system uses two injectors to fire fuel into the transfer port instead of using a carburetor and through the combustion chamber. The design results in smoother delivery and cleaner output. It also eliminates the need to mix gases as oil is introduced to the motor through the throttle body. The TPI system debuted in 2018 but never made it to the motocross side. Personally, I’m not sold on the TPI system, always feeling too rich or clogged.
The new EFI systems found in the SX range take a different approach. This is very similar to the common EFI system found in modern four strokes. The 39mm electronic throttle body is equipped with injectors and works with an electronic power valve to eliminate the need for a carburetor and drain. There are two handlebar-mounted map switches, much like the SX-F model, and riders can choose between a standard power curve or a more aggressive one. This map switch is common for older factory two strokes or those opting for a full ignition kit, but is now a standard option on stock KTMs. And like modern four strokes, maps on two cannot be fully adjusted if needed. All two-stroke SXs are also equipped with electric start.
Aside from the obvious cool factor of the new engine, all two-strokes feature an updated look that’s on par with their four-stroke brethren. The 250 and 300cc models share a frame while the smaller 125cc requires a special frame to accommodate the engine. All three bikes are fitted with a sharp new body style that looks identical to the SX-F model. The brand image is there, that’s for sure. WP Xact suspension components hold this premix burner in place with an adjustable clicker button on the fork and shock. New profiles for the footrest and seat offer more contact with the rider, again the same as the four strokes we had more time. Both designs offer more comfort and control, so they get the thumbs up from our camp.
KTM 125SX 2023
Let’s start small, An electric start on two strokes with a pinhole isn’t really necessary, but man, it’s nice! No more kicks. The entire cockpit on the 125 feels very familiar after spending all day with another KTM six-plus with the same setup. The start button and map switch are both slim and don’t make the handlebars feel cramped. Just like a quick squeeze of the clamp in the kitchen drawer, the mandatory pull of the buttery Brembo brakes and hydraulic clutch settings and we’re ready to hit the track.
The fuel injection on the 125 feels great. It’s very responsive from the start and offers a clean punch from the first gap of the throttle. There is no lag or hesitation in throttle response and the only bogging sensation that occurs can be credited to rider error. It still likes to ride like a traditional 125—powerful and rides wide lines to carry as much momentum as possible. Map two adds more punch from the bottom to midrange power and is my preferred setting, being the bigger rider for the 125.
The hearing experience of 125 is like no other. It makes you feel like you’re setting a lap record, when, in fact, the stopwatch tells a different story. Either way, riding the small-bore two-stroke is really fun, and it makes it hard to wipe that goofy smile off your face. The new KTM 125 SX will be a great choice for young or adult racers looking for a fun bike to add to their collection.
KTM 250SX 2023
The long 250cc two-stroke motorcycle took control of the stadium and saw the fans lined up on the track at the outdoor Nationals. Now, the 250 SX is KTM’s mid-range two-stroke offering. It also received several revisions for the 2023 model year. A new frame, subframe, body work, etc. are all on par with other members of the two and four stroke family. Most notable for the 250 is the fuel injection system.
Like the 125, the larger 250 is sharp and has an immediate throttle response. I love to ride two strokes but often feel a little hesitant on the throttle especially after jumping off the fuel injected four stroke. Now, the two-stroke engine activates immediately and offers real connectivity from the throttle to the rear wheels. Map one is better in the mid to high range, while map two offers more of a downward punch that transitions nicely into the fat mid range. Again, map two is my preferred choice due to its warmer nature and given the softer track conditions. Both maps do feel slightly tilted towards the top end of rpm. Power riding mid-to-top was fine, but the engine started falling flat and pinging as I approached the very top of the range. Indeed the bikes we ride are technically pre-production, and I’m sure it will be successful next September.
The suspension on all two strokes is noticeably softer than the components found on the four stroke. This may be because the bike is lighter than the SX-F model, but it’s worth noting the extra “squish” on the SX. Soft clay conditions also add to this as the bike dives harder into corners and uses more suspension than traditional solid conditions in California. This didn’t hamper performance during our test run, just a note during our fast laps on all three two-stroke models.
KTM 300SX 2023
This is the bike that everyone wants to know. People have been building their own 300s for some time now by removing 300 XC parts and fitting them into their 250 SX. This is a relatively good fixer, but KTM knows their customers want more. Enter 300 SX. Finally, two big steps dedicated to the moto track.
When it comes to the subtleties, the 250 and 300 are very similar. In fact, they are nearly identical except for the larger hole at 300. The 250 hole and step is 72 x 66.4mm, where 300 is 72 x 72mm. This achieves an additional 44 cubic centimeters and increases displacement from 249 to 293.2cc. The frame, suspension, body work and cockpit are all identical on the two larger SX models.
On the track is where the difference becomes clear. 300 is almost as smooth as you can get from two steps. New electronic fuel injection and power valves make throttle response, delivery and output very sweet. There’s not as much real punch from the engine as you’d expect, and you can take the bike in third gear almost anywhere on the track. It’s low torque like a four stroke but maintains a strong turning character in the mid to high. We weren’t big fans of the previous KTM and Husqvarna 300cc bikes that had a light switch powerband, but this bike feels a lot different. Map two again dealt a better punch for more aggressive riders, but map one would be a common rider’s dream.
