2023 KTM SX Range Review

Ryan Nitzen | June 23, 2022
Read any comment thread on social media and you will see the request in two steps. Riders of today and yesterday, full of nostalgia, can’t help but remember the glory days when the sweet scents of premix filled the air. The sights, sounds, and smells of any rider are recognizable. But through thick and thin, times have changed, and four-strokes have dominated the modern motocross scene. This does not mean that two strokes are not common. Look at any enduro or cross-country race and you will find the majority of platform locations filled with two-stroke riders. And that’s not to mention modern-day bike builders taking back the two-stroke projects that would make any moto head foam in the mouth.

Three strokes of fun.

Mac Vienet’s photo

KTM is a brand that puts its fingers on the pulse when it comes to two-stroke ordering. As with a few others on the market (Beta, Sherco, Yamaha and other brands under the KTM umbrella), they see the abiding desire to have two-stroke bikes across the country. News broke about new fuel injection technology for the full line of KTM’s two-stroke, and Team Orange Brigade launched their new bikes at their most recent 2023 model launch.

The bikes we rode at RedBud weren’t exactly the same bikes you’d buy off the showroom floor. These pumpkins were in their final stages of development when we got our hands on them. In fact, fuel injection technicians from Austria were on the right track to receive feedback on the system they designed. The 125, 250 and 300 SX models have been made available to the media while the XC models, which will also feature the same fuel injection technology, will appear in the US later this year. We only received a limited time on all three bikes, but we made the most of it as the three riders take turns on each.

2023 KTM SX EFI SYSTEM
KTM has ditched its TPI system for a more traditional EFI in its new two-stroke off-road line, which now includes all of its engines.

TPI vs. EFI

If you’re anything like me, you’re probably thinking, “I thought KTM was already using two-stroke fuel injection.” That’s right, sort of. The enduro bikes from KTM and Husqvarna were previously marked with TPI, or Transfer Port Injection. This system used two injectors to release the fuel into the transfer ports instead of using a carburetor and passing through the combustion chamber. The design resulted in smoother delivery and cleaner output. It also eliminated the need for gas mixing as the engine was fed oil through the throttle body. The TPI system debuted in 2018 but never really made its way into the motocross side of things. Personally, I’ve never been sold on the TPI regimen, and I’ve always felt too rich or clogged for me.

The new EFI system found in the SX range takes a different approach. It is very similar to the common EFI systems found on modern four-strokes. The 39mm electronic throttle body is injected and works with the electronic power valve to eliminate the need for carburetor and jetting. There are two steering-mounted map switches, just like the SX-F models, and riders can choose between a standard or more aggressive power curve. This map switch is popular with old factory double-strokes or those opting for a full ignition kit, but this is now a standard option on stock KTMs. As with the modern four-stroke, the two-stroke maps can be fully adjusted if required. All SX two-strokes are equipped with electric start, too.

Aside from the obvious cool factor of the new engines, all two-strokes have an updated look that perfectly matches their four-stroke brethren. The 250 and 300 cc models share the frame while the smaller 125 cc model needs a specific frame to accommodate its engine. All three bikes are installed with a sharp new body design that looks identical to the SX-F models. The brand image is right there, that’s for sure. WP Xact suspension components mount these brake-adjustable disc brakes pre-loaded to both the fork and shock. New footrest and seat profiles provide more contact with the passenger, again like the four-strokes we spent more time on. Both designs offer more comfort and control, so these are getting a thumbs up from our campers.

Video | First ride of the 2023 KTMs

This is the video from RedBud MX when we rode All The new 2023 KTM cars: two-strokes, four-strokes, SX, XC… you name it, we rode it.

2023 KTM 125 SX
We were surprised by how well the new EFI system performed with the 125 SX. We also liked the new electric starter. We hate starting the bikes now, even 125 seconds.

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 watched the night before the ride, I heard Jeff Image say, “The A 125 is just a very small car for adults.” This stuck with me all day as I did my best to keep the KTM 125 SX strapped on around the muddy RedBud layout.

Electric start in two small strokes The bore isn’t exactly necessary, but man is nice! No more kicking. The entire cockpit of the 125 felt very familiar after spending all day on six other KTMs with the same setup. Both the start button and the map switch are smooth and do not 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 settings, we were ready to hit the track.

The fuel injection in the 125 looks amazing. It’s responsive right from the start and delivers a clean hit from the first crack of the throttle. There is no lag or hesitation in throttle response, and the only sensation of stumbling can be attributed to rider fault. He still likes to ride like a traditional 125—speeding and riding broad lines to carry as much momentum as possible. The second map added noticeably more hits from the bottom to the midrange power and was my favorite setup, being a bigger 125 rider.

The audio experience of the 125 is unlike anything else. It makes you feel like you’re setting records, when in fact the stopwatch tells a different story. Either way, the small-bore two-stroke ride is totally fun, and makes it hard to wipe that goofy grin off your face. The new KTM 125 SX would be a great choice for young or adult racers looking for a fun bike to add to the collection.

2023 KTM 250 SX
Like previous KTM four-strokes, the two-stroke now offers a map switch on the handlebar. There are two options for the map.

2023 KTM 250 SX

The 250cc two-stroke long car dominated the stadiums and saw fans lining up on the outdoor track. Now, the 250 SX is KTM’s two-stroke middleweight offering. It also received many reviews for 2023. The new frame, subframe, bodywork, etc. are on par with the rest of the family with two- and four-strokes. What distinguishes the 250 is the fuel injection system.

Like the 125, the larger 250 is fast and has instant throttle response. I love two-stroke riding but sometimes I feel a little hesitant on the throttle especially after jumping off the fuel-injected four-stroke. Now, the two-stroke engine wakes up immediately and provides remarkable communication from the throttle to the rear wheel. The first map is better in the mid-to-high range, while the second map offers more low hits that transition well into the meaty mid-range. Once again, the second map was my preferred choice due to its more scenic nature and due to the softer track conditions. Both maps felt a little on the weak side towards the upper end of the rpm. The mid-to-top power ride was fine, but the engine started falling flat and pinging as I got close to the top of the range. Granted the bike we rode was technically pre-production, I’m going to think this will be done by September.

The suspension on all four-strokes felt smoother than the components on the four-strokes. This is probably because the bikes are lighter than the SX-F models, but it’s worth noting the extra “pressure” in the SXs. Soft mud conditions were also added to this as the bikes were diving hard into corners and using more suspension than traditional home-packed conditions in California. It did nothing to hamper performance during our test rides, just a note during quick turns on all three two-stroke models.

2023 KTM 300 SX
Finally, KTM is now offering “big-bore” two-stroke motocross in the 300 SX. It, too, is fuel-injected and a blast to ride.

2023 KTM 300 SX

This is the bike everyone wants to know. People have been building their own 300s for some time now by ripping off parts from the 300 XC and installing them up to the 250 SX. This was a relatively good problem-solving, but KTM knew its customers wanted more. Enter 300 SX. Finally, two big runs dedicated to the motorcycle track.

When it comes to the substantive things, the 250 and 300 are very similar. In fact, they’re nearly identical except for the 300’s larger bore. The 250’s bore and stroke are 72 x 66.4mm, where the 300 is 72 x 72mm. This achieves an additional 44 cc and throws out the displacement from 249 to 293.2 cc. The frame, suspension, bodywork and cockpit are all identical on the two larger SX models.

On the right track where the differences become apparent. The 300 is as smooth as you can get from a two-stroke. A new electronic fuel injection and power valve make throttle response, delivery and output very sweet. There’s no real hit from the engine as you’d expect, and you can pull the bike in third gear just about everywhere on the track. It’s torque as low as a four-stroke but maintains a strong mid-to-high rev character. We weren’t big fans of previous KTM and Husqvarna 300cc engines that had a light switch, but this bike looks a lot different. The second map again presents a better punch for the more aggressive riders, but the first map will be a common rider’s dream.

2023 KTM SX Lineup

2023 KTM SX Range Review | is contained

Even though we only got five laps on each bike during our day at RedBud, it’s easy to see the future of two-stroke technology in good hands. Once again, these new KTMs were still in the final stages of pre-production, and regardless of the suspension settings, they are hard to separate. The new chassis, body and cockpit almost goes 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 definitely a step forward for fans of ready-made mixtures. We consider it an advantage for its ease of use and reduced jetting headache. These bikes will perform at any height and provide a similar feel to reliable old carburetor machines. In the end, we are huge fans of the KTM 2023 two-stroke models and are excited to be mixing up some gas and spinning more revs in the near future. CN

2023 KTM SX Range Cycle News Review

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