Ryan Nitzen | January 16, 2023
KTM enters the “big-bore” two-stroke MX war with its 300 SX all-arounder.
Photos By Ryan Nitzen and Trevor Hunter
Think about it. There’re two main types of motorcycle owners. For one, there is the guy or gal who wants a bike for every kind of riding. They’ve got a fleet of motorcycles in the garage that includes (but is not limited to) a motocrosser, a dual sport, an enduro, a pit bike, etc. If you’re not this person, then you likely know this person. Then, there’s the rider who wants one bike that does it all. This rider makes it work in various conditions and lands somewhere in the middle in terms of general setup. But what if there was a bike that did it all? One bike that virtually eliminated the rest of the quiver? Enter the 2023 KTM 300 SX.
VIDEO | 2023 KTM 300 SX First Ride
KTM did it big this year. Its entire motocross lineup (SX and SX-F models) is all new for 2023. This means every bike received a new frame, new swingarm, new bodywork—you name it. The biggest news, depending on who you ask, comes from the two-stroke department. The premixers stepped into the future and ditched the classic carburetors for a full fuel-injected system. No more carbs and no more TPI (Transfer Port Injection). This new system could be called TBI (Throttle Body Injection), just like all the modern four-strokes. With no TPI, owners are again back to mixing gas. The KTM techs recommended a smooth 60:1 ratio upon delivery. Along with the new fuel injection, the 300 also comes with an electronic powervalve for smoother power delivery.
So, what’s so special about this bike? Essentially, it’s a big-bore version of KTM’s 250 SX, right? Well, kind of. It’s no secret that people have been building their own 300cc motocrossers for some time now. KTM’s offered an OEM 300 SX kit in the past, while others have opted to body bag a 300 parts bike from Facebook Marketplace. The OEM 300cc kit provided a new cylinder, cylinder head, piston, ignition, powervalve and gaskets that were directly swappable to a standard 250cc SX model. The new 2023 300cc takes that hassle of swapping parts off the table and allows the customer to walk out of the dealership with open-class power. Oh yeah, the fuel injection is cool, too.
Looking for a two-stroke motocrosser with open-class power? Here’s KTM’s new 300 SX.
We recently loaded up the 300 and took it to Glen Helen for our first real test ride. We also rode it this summer during KTM’s 2023 model launch at RedBud, but we only rode it for a few laps, as the bike was still in its final stages of development. Glen Helen, with its wide-open straights and steep hillclimbs, is our go-to testing grounds for open-class power like this.
The first thing I noticed was the weight. Or lack thereof. At 219 dry pounds (claimed), the 300 is seven pounds lighter than the current-gen four-stroke KTM 450 SX-F. Lifting it off the stand requires noticeably less muscle, which translates to a lightweight feeling on track. You can easily switch lines and move the bike around in the air. If you’re familiar with two-strokes, this isn’t going to surprise you, but that classic “no engine-brake” feeling was a smile-inducing reminder of how fun a two-smoker can be. Bombing the downhills or carrying roll speed in and through a corner feels easy and smooth on the 300.
Open-class two-stroke motocrossers are notorious for being handfuls on the track; not so with the 300 SX.
Plus, it rides on that new KTM chassis. After having swung my leg over practically every orange ’23 machine already, I’ve become accustomed to the new frame and swingarm combo. I like it. It feels slightly longer than it did in years past, therefore, it creates a stable feeling while at speed. This was something I wanted—rather, needed—while clicking into fourth gear on the start straight or trying to pick a rut at speed. The cockpit is neutral and comfortable right from the get-go and doesn’t feel super “European” like some of the KTMs of the past.
The only thing I really tinkered with was the suspension, as the fork felt a bit harsh and choppered out at times. I softened the compression with the tool-less adjusters and opened the rebound to free up the fork and get more function from the front end. This was especially helpful as the track roughened up later in the day. While the two-stroke certainly feels lighter and more playful, it doesn’t have that weight to plow through braking bumps as a four-stroke does. Again, if you ride a two-stroke, you’re likely already used to this, but if you aren’t, it’s something to keep in mind when setting up your bike.
KTM’s new two-strokes are now fuel injected via its throttle body like traditional four-stroke FI systems. No more TPI. The result? Harder-hitting power. However, you must premix fuel again.
Time to get to the juicy part, the power: 293 cubic centimeters of premix-burning power. This thing comes alive the second you twist that grip. After recently racing a 2023 KTM 300 XC for two hours at the Ironman GNCC, I was slightly familiar with this engine, but the SX model is tuned for a motocross-specific character. Mid- to top-end range is absurd (in a good way), and it pulls like my dad’s old Honda CR500R when opened. Second and third gears are dying to be twisted to the furthest degree. But here’s the best part: Half the time, you don’t even need to feather the clutch to bring this bike back to life. The bottom end is so strong that you can ride this bike lazily just like your favorite four-stroke. Leaving it in one or two gears for the duration of the track is totally doable. In short, it blends the rideability of a four-stroke with the fun of a two-stroke. It’s like the 350 of two-strokes, if you will.
Another new feature is the SX’s electronically operated exhaust powervalve.
While we’re talking power, let’s get into the mapping. The KTM 300 SX comes standard with a selectable two-map switch. Factory stuff, right? It looks like the same unit on the new SX-F models, except there’s no traction control or quickshifter on the two-strokes. Map one (white light) is the standard and mellower of the two maps. That’s because the powervalve only opens up 80 percent in this map. Map two (green light) is the more aggressive setting since it allows the powervalve to open all the way. These two maps noticeably change the engine’s character and provide unique feelings. This can be useful late in the day or if you frequent different styles of tracks. Just think green light means go.
You have two map options available on the fly.
As for where this bike fits in, that’s a different story. It’s an open-class racer, possibly a 450 competitor (depending on what race series you ask), a fleet killer, or just the go-to ride if you’re looking for fun. That’s what it’s been for me lately. If I’m having trouble deciding which bike to ride (a good problem to have, I know), I just pick the 300. It’s fast, light and just plain fun. The only real issue I see is it being the first model year with the EFI system. I haven’t seen or heard of any real problems with this, but new technologies can be prone to glitches.
If you’re wondering, the KTM 300 SX is eligible for several racing classes in motocross around the country, especially age classes, and can be ridden in any 450cc class, including Open Pro Sport, at Loretta Lynn’s. However, despite having “SX” in its name, you won’t be seeing it raced in AMA Pro Motocross or Supercross anytime soon; it’s not eligible for either 250SX/MX or 450SX/MX classes.
The 300 SX feels lighter and nimbler than 450cc four-strokes.
Regarding competition, the KTM 300 SX has only the Beta 300 RX to be concerned about. The RX made its debut last year, and the current model sells for $9399, which is $200 more than the KTM. One of the main differences between the KTM and Beta is the fueling system. The Beta is carbureted, via a 38mm PWK Keihin.
We’re excited that KTM is still putting this much effort into the two-stroke scene. No matter what kind of buyer you are—the one who wants a bike for every type of riding, or the one who wants one bike to do it all—put the KTM 300 SX on your short list of must-rides. CN
2023 KTM 300 SX Specifications
| MSRP: |
$9199 |
| Engine Type: |
2-stroke, single |
| Displacement: |
293.2cc |
| Bore x Stroke: |
72 x 72mm |
| Cooling System: |
Liquid |
| Starting System: |
Electric |
| Fueling: |
Fuel Injection (Throttle Body Injection) |
| Transmission: |
5-speed, w/ hydraulic clutch |
| Frame: |
Steel central-tube |
| Subframe: |
Polyamide, reinforced aluminum |
| Front Suspension: |
WP Xact 48mm |
| Rear Suspension: |
WP Xact Monoshock with linkage |
| Front-Wheel Travel: |
12.2 in. |
| Rear-Wheel Travel: |
11.8 in. |
| Front Wheel: |
21 in. |
| Rear Wheel: |
19 in. |
| Front Tire: |
Dunlop Geomax MX-33F |
| Rear Tire: |
Dunlop Geomax MX-33 |
| Front Brake: |
Brembo 260mm |
| Rear Brake: |
Single 220mm, Brembo caliper |
| Wheelbase: |
58.7 in. |
| Steering Head Angle: |
63.9° |
| Seat Height: |
37.7 in. |
| Ground Clearance: |
13.9 in. |
| Fuel Capacity: |
1.9 gal. |
| Weight (no fuel, claimed): |
219 lbs. |
