The 2021 KTM motocross and supercross lineup consists of six motorcycles—three each of four-strokes and two-stroke.
The four-stroke models are the 450 SX-F, 350 SX-F, and 250 SX-F, while the two-strokes are the 250 SX, 150 SX, and 125 SX. Most of the changes for 2021 apply to all six models, though there are some exceptions. Let’s take a quick look at the updates to the 2021 KTM motocrossers and supercrossers.
- All six 2021 KTM SX-F models get a new WP Xact fork. While the fork remains an air-spring design, it gets new internals. The bypasses have been enlarged “to reduce pressure peaks,” according to KTM. Complementing that is a smaller rebound spacer in the air leg. That means more air volume in the negative chamber and a more linear action with a spring-style feel. Theirs is also a new mid-valve damping system that KTM says improves feedback and feel. Overall, the new WP Xact forks are claimed by KTM to have “refined performance, comfortable, and handling.”
- The WP Xact shock also gets a minor update. There’s a new link-piston O-ring, which KTM tells us will “reduce fading and improve consistency over long motos.”
2021 KTM 250 SX-F
- There are new SKF bearing seals in the linkage for freer movement. KTM says this results in “better suspension feel and performance throughout the shock stroke.”
- With the suspension and linkage updates comes new settings. KTM isn’t revealing what’s new, but the company does say the result is “better traction, improved comfort and confidence-inspiring feel.”
- Dunlop Geomax MX33 tires are now shod on the Excel rims.
- The SOHC KTM 450 SX-F gets some motor updates not found on the DOHC 250 and 350. There’s a new con rod with a copper-beryllium upper bush for faster revving, along with new rocker arms up top for the titanium valves. The mapping has been changed to punch up the low-end power, and map 2 is now the “extreme performance option,” according to KTM. Also, the 450 gets a new hour-meter casing.
2021 KTM 250 SX
- The two-strokes get two changes you won’t see in the four-strokes. Still working with carburetors, the 250 SX, 150 SX, and 125 SX have a new smoother roller-action throttle assembly. Also, the inner clutch hub sleeves are thicker to beef up reliability.
- KTM gives the 2021 125 SX a new piston. It is made of a harder material to increase durability while maintaining performance.
2021 KTM 450 SX-F (350 SX-F and 250 SX-F) Specs
ENGINE
- Type: Single-cylinder four-stroke
- Displacement: 450cc (350 SX-F: 350cc; 250 SX-F: 250cc)
- Bore x stroke: 95 x 63.4mm (350 SX-F: 88 x 57.5mm; 250 SX-F: 78 x 52.3mm)
- Compression ratio: 12.75:1 (350 SX-F: 14.2:1; 250 SX-F: 14.4:1)
- Valvetrain: SOHC, 4 valves (350 SX-F and 250 SX-F: DOHC, 4 valves)
- Starting: Electric w/ Lithium-ion 12.8-volt 2 Ah battery
- Lubrication: Pressure Lubrication with 2 Pumps
- Fueling: Keihin EFI w/ 44mm throttle body
- Transmission: 5-speed
- Clutch: Wet multi-disc DDS clutch w/ Brembo hydraulics
- Final drive: 5/8” x ¼” chain
CHASSIS
- Frame: Central double-cradle chromoly steel
- Subframe: Aluminum
- Handlebar: Neken aluminum
- Front suspension: Fully adjustable WP Xact inverted 48mm fork; 12.2 inches
- Rear suspension: Linkage-assisted fully adjustable WP Xact shock; 11.8 inches
- Wheels: Excel
- Front wheel: 21 x 1.60
- Rear wheel: 19 x 2.15
- Tires: Dunlop Geomax MX33
- Front tire: 80/100 x 21
- Rear tire: 120/90 x 19
- Front brake: 260mm disc w/ Brembo caliper
- Rear brake: 220mm disc w/ Brembo caliper
DIMENSIONS and CAPACITIES
- Wheelbase: 58.5 inches (± 0.4 in)
- Rake: 26.1 degrees
- Triple clamp offset: 22mm
- Seat height: 37.4 degrees
- Ground clearance: 14.6 inches
- Fuel capacity: 1.85 gallons
- Curb weight: 234 pounds (350 SX-F: 231 pounds; 250 SX-F: 229 pounds)
2021 KTM 250 SX (150 SX and 125 SX) Specs
ENGINE
- Type: Single-cylinder two-stroke
- Displacement: 249cc (150 SX: 144cc; 125 SX: 125cc)
- Bore x stroke: 66.4 x 72mm (150 SX: 58 x 54.5mm; 125 X: 54 x 54.5mm)
- Starting: Kick
- Lubrication: Premix @ 40:1
- Fueling: 38mm Mikuni TMX carburetor
- Transmission: 5-speed (150 SX and 125 SX: 6-speed)
- Clutch: Wet multi-disc DDS clutch w/ Brembo hydraulics
- Final drive: 5/8” x ¼” chain
CHASSIS
- Frame: Central double-cradle chromoly steel
- Subframe: Aluminum
- Handlebar: Neken aluminum
- Front suspension: Fully adjustable WP Xact inverted 48mm fork; 12.2 inches
- Rear suspension: Linkage-assisted fully adjustable WP Xact shock; 11.8 inches
- Wheels: Excel
- Front wheel: 21 x 1.60
- Rear wheel: 19 x 2.15
- Tires: Dunlop Geomax MX33
- Front tire: 80/100 x 21
- Rear tire: 110/90 x 19 (150 SX and 125 SX: 100/90 x 19)
- Front brake: 260mm disc w/ Brembo caliper
- Rear brake: 220mm disc w/ Brembo caliper
DIMENSIONS and CAPACITIES
- Wheelbase: 58.5 inches (± 0.4 in)
- Rake: 26.1 degrees
- Triple clamp offset: 22mm
- Seat height: 37.4 degrees
- Ground clearance: 14.8 inches
- Fuel capacity: 2.0 gallons
- Curb weight: 222 pounds (150 SX and 125 SX: 205 pounds)
2021 KTM Motocross and Supercross Lineup Photo Gallery
