KTM 250 SX-F Review (2015–2020) – Used Motocross Buyer’s Guide

Want a 250 four-stroke that screams to 14,000 RPM, starts with the touch of a button, and feels light enough to throw around like a BMX? The KTM 250 SX-F is that bike. It’s the European benchmark for power-to-weight, loaded with premium components and championship-winning DNA. Read on as we cover how it rides, what changed over the years, what to look for when buying used, and why the SX-F remains one of the most desirable 250 motocross bikes on the market.

Overview & first impressions

If performance and technology top your list, the KTM 250 SX-F delivers both in spades. From 2015 onward, KTM consistently pushed the limits of 250 four-stroke development—introducing class-leading horsepower, lightweight chromoly steel frames, and the convenience of electric start on every model (years before the Japanese brands caught up).

These bikes are razor-focused race machines. They feel light, rev freely, and handle with precision once properly dialled in. The trade-off? They’re more high-strung than a Honda or Yamaha and reward riders who ride hard and maintain them properly.

Model evolution through this era:

  • 2015: Already electric-start and fast; used WP 4CS forks (a bit firm).

  • 2016: Full redesign—lighter, more powerful, with improved chassis and suspension geometry.

  • 2017–2018: Switched to WP AER 48 air forks for further weight reduction and tunability.

  • 2019–2020: Refined WP XACT suspension, traction control, map switch, and even smoother power.

Even the earliest bikes in this range feel remarkably modern compared to their competitors from the same years.

Verdict box

Pros:

  • Class-leading horsepower and top-end pull

  • Standard electric start on all years

  • Lightweight and agile – one of the lightest 250Fs made

  • Premium components: Brembo brakes, hydraulic clutch, Excel rims

  • Easy-to-adjust mapping and (on later years) traction control

Cons:

  • High-revving engine needs to be ridden aggressively for best performance

  • Air forks (2017–2020) can feel harsh or need careful setup

  • Slightly higher maintenance costs and part prices

  • More expensive on the used market than Japanese rivals

Verdict:
The KTM 250 SX-F is the thoroughbred of the 250 class—made for those who love to push limits. It’s fast, refined, and feature-packed, offering race-winning performance for riders ready to maintain it properly.

KTM 250 SX-F FAQ

Does every KTM 250 SX-F have electric start?
Yes. Every 2015–2020 model includes electric start as standard.

When did it get air forks?
From 2017 onward, KTM used WP AER 48 forks instead of the older 4CS units.

Is the SX-F good for casual riders?
It can be—but it shines brightest when ridden aggressively. It’s smooth at low RPM but truly comes alive at higher revs.

Any reliability concerns?
Not if maintained correctly. Regular oil changes, valve checks, and air filter care are crucial. KTM’s engines are strong but more sensitive to neglect.

Is it expensive to maintain?
Parts can be slightly pricier than Japanese bikes, but the build quality is top-notch, and service intervals are similar.

Strengths, weaknesses & used-buying advice

Engine & performance

KTM’s 250 SX-F engine is pure race engineering. Lightweight internals, a twin-cam head, and precise fuel injection give it one of the broadest and strongest powerbands in the 250 class.

  • 2015–2016: Already powerful, with a big top-end surge and strong midrange. The 2016 redesign shaved weight and added even more revs.

  • 2017–2018: Slightly smoother power delivery but same addictive top-end.

  • 2019–2020: Near-perfect refinement—linear from bottom to mid, then a screaming top-end that doesn’t quit.

Below midrange, the engine feels tame and tractable—easy to control. But twist the throttle hard, and it erupts with high-RPM fury. Expert riders love this; beginners may find it a bit demanding at first.

Despite the performance, it’s surprisingly manageable, with excellent fueling and predictable response.

Chassis, suspension & handling

KTM’s chromoly steel frame gives the SX-F a unique feel compared to aluminium-framed rivals. It flexes slightly to absorb impacts, making it comfortable over rough ground, yet remains precise in corners.

The bikes are extremely light—typically 3–4 kg less than Japanese 250Fs—and it shows. They change direction effortlessly and feel perfectly balanced in the air.

Suspension highlights:

  • 2015–2016: WP 4CS forks – firm and sometimes harsh; many riders revalved or upgraded.

  • 2017–2018: WP AER air forks – lighter, tunable with a pump, but require regular pressure checks.

  • 2019–2020: WP XACT forks – much improved, offering a more supple feel with air convenience.

The rear WP shock complements the front well, offering great traction and consistent damping.

Build quality & components

KTM leads the way in spec. All 250 SX-Fs come with:

  • Hydraulic Brembo clutch – smooth, self-adjusting, light lever feel

  • Brembo brakes – strong stopping power and feel

  • Excel rims, Neken handlebars, ODI lock-on grips

  • Hour meter as standard

Later models also feature selectable engine maps and traction control, which can be toggled from the handlebar switch—rare in this class at the time.

These touches make the SX-F feel like a factory race bike right off the stand.

Maintenance & reliability

Despite the performance, KTMs are tough when serviced correctly. Follow these key points:

  • Oil & filter every 5–8 hours of racing or 10–12 hours of casual riding.

  • Valve checks around 30–40 hours.

  • Replace the timing chain every 60–80 hours as preventative maintenance.

  • Use quality oil (Motorex or equivalent) and genuine filters to ensure long life.

If a used bike idles quietly, starts easily, and doesn’t smoke, it’s likely solid. Avoid bikes that rattle excessively at idle or have sluggish starters—could indicate worn internals or other issues.

Used-buying tips by year

  • 2015–2016: Early electric-start bikes; 4CS forks often revalved—ask if suspension work’s been done.

  • 2017–2018: Air-fork years. Check fork air pressure and seals; neglect can cause poor feel.

  • 2019–2020: Most refined setup. Make sure traction control and map switch work properly.

Inspect for frame cracks around footpegs and shock mounts (rare but possible if raced heavily). Check clutch fluid condition (shouldn’t be dark) and verify hour meter reading against overall wear.

A well-kept SX-F starts instantly, idles smoothly, and revs cleanly with no hesitation.

The KTM 250 SX-F (2015–2020) remains the benchmark for 250cc motocross performance. Lightweight, powerful, and packed with race-ready tech, it’s a bike that rewards riders who like to push the pace. With electric start, hydraulic clutch, and top-shelf components on every model, it’s hard to fault—just maintain it well, and you’ll own one of the sharpest, fastest, and most advanced used MX bikes available.