KTM SX-F 450 Top Speed, Specs & Review
TL;DR
- The 2026 KTM 450 SX-F is the highest-output standard 450 motocross bike tested in Dirt Rider’s 2026 comparison, putting 56.7 hp and 34.5 lb-ft of torque to the rear wheel.
- Top speed on stock MX gearing is approximately 76 mph (123 km/h) on a flat hardpack surface; KTM does not publish an official top-speed figure.
- The 449.9cc liquid-cooled SOHC single runs a 13.1:1 compression ratio with Keihin EFI and a 44mm throttle body.
- Wet weight is 240 lb on the Dirt Rider automotive scales — one of the lightest in class.
- 2026 MSRP is $11,649 for the standard model
2026 KTM 450 SX-F Full Specs
The 450 SX-F has run the current platform since 2023, with a mid-generation update in 2025 and only minor changes for 2026. All dimensions and specs below are from the official KTM US specification page for the 2026 model.
| Spec | 2026 KTM 450 SX-F |
|---|---|
| Engine | 449.9cc liquid-cooled SOHC 4-stroke single |
| Bore x Stroke | 95 mm x 63.4 mm |
| Compression Ratio | 13.1:1 |
| Fuel System | Keihin EFI, 44mm throttle body |
| Transmission | 5-speed, wet multi-disc DDS clutch, Brembo hydraulics |
| Rear Wheel Power | 56.7 hp / 34.5 lb-ft torque (Dirt Rider dyno, 2025) |
| Frame | 25CrMo4 chromoly steel double-cradle |
| Front Suspension | WP XACT-USD AER 48mm air fork, 310mm travel |
| Rear Suspension | WP XACT Monoshock with linkage, 300mm travel |
| Front Brake | Brembo dual-piston caliper, 260mm disc |
| Rear Brake | Brembo single-piston caliper, 220mm disc |
| Seat Height | 958mm (37.7 in) |
| Ground Clearance | 343mm (13.5 in) |
| Fuel Capacity | 7.2 L (1.9 gal) |
| Wet Weight | 240 lb (Dirt Rider, 2025) |
| Tires | Dunlop Geomax MX34 (front and rear) |
| MSRP (2026, USA) | $11,649 |
KTM 450 SX-F Top Speed: What the Numbers Actually Mean
The KTM 450 SX-F top speed on a stock 13/48 MX sprocket setup is approximately 76 mph (123 km/h) on a flat, hardpack surface. KTM does not publish an official top-speed figure for the SX-F — this is a race-geared motocross bike, not a highway machine, and the factory has no reason to test it that way.
The 76 mph figure is consistent with what you get when you do the math: the 449.9cc engine revs to around 11,000 rpm at peak power, and the stock gearing runs out of room right around sixth gear on open ground. Real-world GPS tests from riders on flat tracks and fields consistently land in the 73–80 mph range, depending on rider weight, ground conditions, and exact gearing.
You’ll sometimes see inflated figures of 116–123 mph cited on various sites — those numbers mix up dyno rpm simulations with actual road speed, or refer to hypothetical long-track gearing swaps (a 14 or 15-tooth front sprocket changes the picture significantly). Dirt Bike Magazine addressed this directly: “around the 120-mph mark is in the hunt for a top-speed run on a properly geared 450” (Dirt Bike Magazine, 2023), meaning that’s a special gearing experiment, not what rolls off the showroom floor.
For a motocross bike, top speed is largely irrelevant anyway. What matters is what happens between zero and 50 mph, and the SX-F is extremely fast through that range — particularly off the gate with launch control engaged.
Engine and Power Delivery
The 450 SX-F’s engine is the highest-output unit in the 2026 standard 450 motocross class. Dirt Rider’s Dynojet 250i rear-wheel dynamometer recorded 56.7 hp and 34.5 lb-ft of torque — highest of the seven bikes in their 2026 450 Motocross Comparison Test (Dirt Rider, 2025).
The SOHC single-cylinder layout runs high compression (13.1:1) and a large 44mm Keihin throttle body. That combination produces a power character that builds linearly from low in the rev range rather than hitting an abrupt mid-range spike. Dirt Rider’s test rider put it plainly: “It offers good all-around power that builds controllably. Roll-on is manageable and it revs well too.”
Two engine maps are standard via the handlebar-mounted switch. Map 1 gives you a smoother, more linear curve suited to rough tracks or wet conditions. Map 2 sharpens throttle response and adds aggression for hardpack days when you want every bit of output on tap. Traction control can be toggled from the same switch — a practical setup that doesn’t require digging through a menu.
The engine also ships with launch control and a quickshift function for clutchless upshifts. Launch control holds a steady rev ceiling off the gate, then clears itself at a set point in first gear. It’s a genuine raceday feature, not a marketing bullet point.
What Does the Engine Weigh?
The complete engine assembly weighs 26.8 kg (59.1 lb) per KTM, and the entire bike with fuel comes in at 240 lb — significant for a 450 that makes this much power.
Frame, Suspension, and Chassis
The 2025 update reworked the chromoly steel double-cradle frame, thinning certain wall sections, adding cutouts at the rear shock mount, and revising engine mounts. The result was a 300-gram reduction in frame weight and measurably better torsional flex — a direct response to factory riders and paying customers who called the 2023–2024 chassis too stiff.
For 2026, the frame carries over unchanged. The changes are limited to a new radiator cap, a CPC fuel connector protection cap, and updated graphics.
Front suspension is a 48mm WP XACT AER (air fork with USD layout), with 310mm travel. Rear is a WP XACT Monoshock with linkage and 300mm travel. Both are tool-free adjustable. The air fork is notable — most Japanese brands use coil-spring forks at this price point, and the air unit allows broader preload adjustment without a spring swap.
Stock settings are track-tested and reasonably dialed for a mid-weight 160–175 lb rider. Heavier riders will want more air pressure in the fork and may benefit from stiffer rear spring rates — KTM offers this through their PowerParts catalog.
Brembo brakes front and rear are not a marketing upgrade on a bike at this price, they’re standard spec. The front 260mm disc with a dual-piston caliper has more than enough power to stoppie a 450 on hardpack; modulation is what separates it from lesser setups, and Brembo delivers that.
Electronics and Features
The 450 SX-F electronics package in 2026 includes:
- Two engine maps (selectable on handlebar switch)
- Traction control (on/off)
- Launch control
- Quickshifter (clutchless upshifts)
- Electric start (12.8V 2Ah lithium-ion battery under the seat)
The Connectivity Unit Offroad (CUO) — KTM’s Bluetooth-enabled app interface that allows mapping, suspension setup logging, and ride data — is available as a KTM PowerParts accessory on the standard 450 SX-F and comes standard on the Factory Edition.
Honest Assessment: Who Should Buy the KTM 450 SX-F
The SX-F is the right bike for riders who put in real track time and want the highest verified output in the standard 450 class. The engine is fast and tractable, the electronics package is the best in the class for a base-model bike, and the weight is competitive with anything on the market.
The seat height at 958mm (37.7 in) is tall. Shorter riders will be on tiptoe at stops, and beginners who aren’t yet comfortable with a tall, aggressive motocross machine will find it a handful. This is not a first-dirt-bike scenario.
The $11,649 MSRP is also the highest end of the standard 450 class (Dirt Rider, 2025). You get a lot for that — Brembo brakes, WP air forks, launch control, and the class-leading dyno numbers — but budget matters. The 350 SX-F at a lower price point is worth considering for riders who don’t need every horsepower the 450 offers.
The 2023–2024 chassis stiffness issue that drew complaints from factory riders has been addressed in the current frame. Riders who avoided the SX-F in those years based on handling reports should note that the 2025 and 2026 models are riding on a different chassis character.
KTM 450 SX-F Maintenance Intervals to Know
The SX-F runs a non-sealed 520 chain that needs lube every ride on a dusty track — DID or RK are the standard replacements when the time comes. The high-compression engine runs premium fuel and the radiator uses a 1.8-bar cap (higher than the 1.1-bar units on Japanese bikes), so don’t substitute a random cap from the parts bin.
Valve clearance checks on a high-revving 450 at 13.1:1 compression aren’t something to skip. KTM recommends inspection intervals that vary by riding intensity — check the manual and stick to it. A tight exhaust valve goes from “quiet knock” to “bent valve” faster than you’d expect on a bike working this hard.
Frequently Asked Questions About the KTM 450 SX-F
What is the top speed of the KTM 450 SX-F?
On stock MX gearing (13/48 sprocket ratio), the KTM 450 SX-F reaches approximately 76 mph (123 km/h) on a flat hardpack surface. KTM does not publish an official top-speed figure. Figures above 100 mph that appear on other sites refer to hypothetical long-track gearing configurations, not a stock bike.
How much horsepower does the 2026 KTM 450 SX-F make?
Dirt Rider’s in-house Dynojet 250i dynamometer recorded 56.7 hp and 34.5 lb-ft of torque at the rear wheel for the 2026 450 SX-F — the highest figures among the seven bikes in their 2026 450 Motocross Bike Comparison Test (Dirt Rider, 2025).
How much does the 2026 KTM 450 SX-F weigh?
The 2026 KTM 450 SX-F weighs 240 lb wet, as measured on Dirt Rider’s automotive scales (Dirt Rider, 2025). That makes it one of the lightest bikes in the standard 450 motocross class.
What is the MSRP for the 2026 KTM 450 SX-F?
The 2026 KTM 450 SX-F has a US MSRP of $11,649. The Factory Edition, which adds an Akrapovic slip-on, Selle Dalla Valle seat, Hinson clutch cover, and standard CUO electronics unit, carries a higher price. Dealer markup and destination charges apply separately.
Is the KTM 450 SX-F good for beginners?
No. The 450 SX-F is a purpose-built competition motocross bike with a 37.7-inch seat height, 56.7 rear-wheel horsepower, and aggressive power delivery on Map 2. Riders still learning bike control on dirt should start on a smaller-displacement machine — a 250F or a trail-oriented 450 with a softer power map is a more practical starting point.
What is the difference between the KTM 450 SX-F and the Factory Edition?
The standard 450 SX-F and the Factory Edition share the same engine and frame. The Factory Edition adds factory-team graphics, a Selle Dalla Valle seat, an Akrapovic slip-on silencer, orange-anodized triple clamps, a holeshot device, a skid plate, a Hinson clutch cover, and the CUO Connectivity Unit as standard equipment. The standard model can accept the CUO as a PowerParts add-on.
What tires does the KTM 450 SX-F come with?
The 2026 KTM 450 SX-F ships with Dunlop Geomax MX34 tires front and rear. KTM switched its full-size motocross range to this tire for the 2025 model year.
Key Takeaways
- The 2026 KTM 450 SX-F puts 56.7 hp and 34.5 lb-ft of torque to the rear wheel — highest in the standard 450 class per Dirt Rider’s 2026 comparison.
- Top speed on stock gearing is approximately 76 mph; inflated figures cited elsewhere refer to different gearing setups or dyno simulations.
- The 2025 frame update resolved the chassis stiffness issues that drew criticism from 2023–2024 models.
- At $11,649 MSRP and 240 lb wet, you’re getting competitive weight and the most electronics content in the standard 450 class.
- This is a race bike — tall seat, aggressive ergonomics, and a non-sealed chain demand a rider who’s already comfortable on dirt.
