Ryan Nitzen | June 23, 2022
Read any comment thread on social media and you’ll see the demand for two-strokes. The nostalgia-filled riders of today and yesteryear can’t help but reminisce on the glory days when the sweet smells of premix filled the air. The sights, sounds and smells are recognizable to 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 aren’t popular. Look at any enduro or cross-country race and you’ll find the majority of the podium spots filled by riders on two-strokes. And that’s without mentioning the modern-day bike builders who restore two-stroke projects that would make any moto-head foam at the mouth.
Photography by Mack Faint
KTM is a brand with their fingers on the pulse when it comes to two-stroke demand. As with a few others in the marketplace (Beta, Sherco, Yamaha and the other brands under the KTM umbrella), they see the unwavering want for two-stroke bikes around the country. News broke of new fuel injection technology for the full line of KTM two-strokes and the Orange Brigade debuted their new bikes at the recent 2023 model launch.
The bikes we rode at RedBud weren’t exactly the same bikes you’ll buy off the showroom floor. These pumpkins were in their final stages of development when we got our hands on them. In fact, the fuel injection technicians from Austria were at the track taking feedback on the system they designed. The 125, 250 and new 300 SX models sat at the media’s disposal while the XC models, which will also have the same fuel-injection technology, will show up stateside later this year. We only received limited time on all three bikes but made the most of it with all three of our riders taking turns on each.
TPI vs. EFI
If you’re like me, you’re probably thinking, “I thought KTM was already using fuel injection on their two-strokes.” It’s true, well, sort of. The enduro bikes from KTM and Husqvarna previously featured TPI, or Transfer Port Injection. This system used two injectors to shoot fuel into the transfer ports rather than using a carburetor and going through the combustion chamber. The design resulted in smoother delivery and a cleaner output. It also eliminated the need to mix gas as oil was fed into the motor via the throttle body. The TPI system debuted in 2018 but never made its way to the motocross side of things. Personally, I wasn’t sold on the TPI system, always felt too rich or clogged up to me.
The new EFI system found in the SX range takes a different approach. It’s very similar to the common EFI systems found in the modern four-strokes. The electronic 39mm throttle body is equipped with injectors and works with the electronic powervalve to eliminate the need for carburetors and jetting. There are two handlebar-mounted map switches, just like the SX-F models, and riders can pick between a standard or more aggressive power curve. This map switch is common for old factory two-strokes or those who opt for a full ignition kit, but this is now a standard option on the stock KTMs. And just like the modern four-strokes, the maps on the two-strokes can be fully tuned if needed. All the SX two-strokes are outfitted with electric start, too.
Aside from the obvious cool factor of the new engines, all the two-strokes sport an updated look that’s right on par with their four-stroke brethren. The 250 and 300cc models share a frame while the smaller 125cc needed a specific frame to accommodate its engine. All three bikes are mounted up with the sharp new body styling that looks identical to that of the SX-F models. The brand image is on point there, that’s for sure. WP Xact suspension components hold up these premix burners with adjustable clicker dials on both the fork and shock. New profiles for the footpegs and seat offer more contact with the rider, again the same as the four-strokes that we have had more time on. Both designs offer more comfort and control, so those get thumbs up from our camp.
VIDEO | First Ride 2023 KTMs
Here’s the video from RedBud MX when we rode all the new 2023 KTMs: two-strokes, four-strokes, SX, XC… you name it, we rode it.
2023 KTM 125 SX
Let’s start small. I can’t even remember the last time I rode a 125. But in a video I saw the night before riding, I heard Jeff Emig say, “A 125 is just a supermini for adults.” That stuck with me all day as I did my best to keep the KTM 125 SX pegged around the loamy RedBud layout.
Electric start on a small-bore two-stroke isn’t exactly necessary, but man is it nice! No more kicking. The entire cockpit on the 125 felt uber-familiar after spending all day on six-plus other KTMs with the same setup. Both the start button and map switch are sleek and don’t make the handlebars feel cramped. Just like a quick squeeze of those tongs in the kitchen drawer, a mandatory pull of the buttery Brembo brakes and hydraulic clutch setups and we were ready to hit the track.
Fuel injection on the 125 feels amazing. It’s super responsive right from the get-go and offers a clean hit from the first crack of the throttle. There’s no lag or hesitation in the throttle response and the only bogging sensation that happens can be credited to rider error. It still likes to be ridden like a traditional 125—revved out and riding wide lines to carry as much momentum as possible. Map two added noticeably more hit from the bottom to midrange power and was my preferred setting, being a bigger rider for a 125.
The auditory experience of the 125 is unlike anything else. It makes you feel like you are setting lap records, when, in reality, the stopwatch tells a different story. Either way, riding a small-bore two-stroke is flat out fun, and it makes it hard to wipe that goofy smile off your face. The new KTM 125 SX is going to be a great option for young racers or adults looking for a fun bike to add to the collection.
2023 KTM 250 SX
The 250cc two-stroke long ruled the stadiums and saw fans lining the track at the outdoor Nationals. Now, the 250 SX is the middleweight two-stroke offering from KTM. It also received several revisions for the 2023 model year. A new frame, subframe, body work, etc. are all on par with the rest of its two- and four-stroke family members. Most notable for the 250 is the fuel-injection system.
Like the 125, the bigger 250 is snappy and has immediate throttle response. I love riding two-strokes but often feel a bit of hesitation in the throttle especially after jumping off a fuel-injected four-stroke. Now, the two-stroke engine wakes up instantly and offers noticeable connectivity from the throttle to the rear wheel. Map one is better in the mid-to-top range, while map two offers more punch down low which transitions nicely to a meaty midrange. Again, map two was my preferred choice for its heartier nature and given the softer track conditions. Both maps did feel a bit on the lean side towards the top end of the rpm. Riding the power in the mid-to-top was fine, but the engine began to fall flat and ping as I neared the very top of the range. Granted the bike we rode was technically pre-production, and I’m going to believe this will be worked out come September.
Suspension on all the two-strokes felt softer than the components found on the four-strokes. This is possibly because the bikes are all-around lighter than the SX-F models, but it is worth noting the extra “squish” in the SXs. Soft loamy conditions also added to this as the bikes were diving harder into the corners and using up more suspension than the traditional hard packed conditions back home in California. This did nothing to hamper the performance during our test rides, just a note during our quick spin on all three two-stroke models.
2023 KTM 300 SX
This is the bike everyone wants to know about. People have been building their own 300s for some time now by taking parts off the 300 XC and bolting them up to their 250 SX. This was a relatively good problem solver, but KTM knew their customers wanted more. Enter the 300 SX. Finally, a big-bore two-stroke that’s dedicated to the moto track.
When it comes down to the nitty gritty, the 250 and 300 are very similar. In fact, they’re almost identical save the larger bore on the 300. The 250 bore and stroke are 72 x 66.4mm, where the 300 is 72 x 72mm. This achieves an extra 44 cubic-centimeters and bumps the 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 differences become clear. The 300 is about as smooth as you can get from a two-stroke. The new electronic fuel injection and powervalve make throttle response, delivery and output ever so sweet. There’s no real hit from the engine like you’d expect, and you can lug the bike in third gear almost everywhere on the track. It’s torquey down low like a four-stroke but maintains that strong rev character in the mid to top. We weren’t huge fans of the previous KTM and Husqvarna 300cc motors which had a light-switch powerband, but this bike feels much different. Map two again packs a better punch for more aggressive riders, but map one will be the common rider’s dream.
2023 KTM SX Range Review | Wrap Up
While we only got about five laps on each bike during our day at RedBud, it’s easy to see the future of two-stroke technology is in good hands. Again, these new KTMs were still in the final stages of pre-production, and aside from suspension settings, it’s hard to pick them apart. New chassis, bodywork and rider cockpits almost go unnoticed since everyone is talking about the new engine, but these changes all felt familiar and comfortable after riding the new four-stroke models. Fuel injection is certainly a step forward for premix lovers. We see it as an advantage for its ease of use and the reduction in jetting headaches. These bikes will perform at any altitude and offer a similar feel to the old trusty carbureted machines. In the end, we’re more than impressed with KTM’s 2023 two-stroke models and are excited to mix some gas and spin more laps in the coming future. CN