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Cross - Motocross · 2021

450 SX-F Factory

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MotoLibrary Score
55 /100 Balanced
Power/Weight
0.63 hp/kg
Engine
449 ccm

2021 Ktm 450 SX-F Factory Technical Analysis & Specification Breakdown

Engineered by Ktm for the cross - motocross motorcycle segment, the 2021 Ktm 450 SX-F Factory relies on a 449.3 cc (27.4 cu in) liquid-cooled single cylinder, four-stroke powerplant. In factory specification, peak output is rated at 63 HP (46 kW), transferring power to the rear wheel through a 4-speed gearbox and chain final drive. With a specific output of 140.2 HP per liter, the engine character is placing it firmly in high-revving supersport territory where top-end breathing dominates.

On the scales, the 450 SX-F Factory measures 100.5 kg (222 lbs) dry, translating to a power-to-weight ratio of 0.63 HP/kg (1.6 kg per horsepower). Rider ergonomics and chassis geometry center around a 950 mm (37.4 in) seat height — reflecting a long-travel chassis stance that favors ground clearance and off-pavement control, combined with a 1,485 mm (58.5 in) wheelbase engineered for balanced agility and highway composure. The 7-liter (1.8 US gal) fuel tank supports practical everyday commuting and weekend road stints.

Within MotoLibrary's Ktm archive, this model family spans 3 indexed model years from 2021 to 2024, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.

Specific Output
140.2 HP/L
Power-to-Weight
0.63 HP/kg (1.6 kg/HP)
Standover Height
950 mm (37.4 in)
Engine
Displacement 449.3 ccm (27.42 cubic inches)
Engine Type Single cylinder, four-stroke
Power 63.0 HP (46.0 kW))
Bore x Stroke 95.0 x 63.4 mm (3.7 x 2.5 inches)
Fuel System Injection
Fuel Control Single Overhead Cams (SOHC)
Ignition Keihin EMS
Cooling Liquid
Transmission
Gearbox 4-speed
Final Drive Chain (final drive)
Clutch Wet, DDS multi-disc clutch, Brembo hydraulics
Driveline 5/8 x 1/4
Performance
Exhaust Akrapovič Slip-On silencer
Chassis
Frame Type 25CrMo4 steel central-tube
Rake 26.1°
Front Suspension WP XACT-USD, Ø 48 mm
Front Travel 310 mm (12.2 inches)
Rear Suspension WP XACT Monoshock with linkage
Rear Travel 300 mm (11.8 inches)
Wheelbase 1485 mm (58.5 inches)
Ground Clearance 370 mm (14.6 inches)
Wheels & Brakes
Front Brakes Single disc. Brake calipers on floating bearings
Front Brake Ø 260 mm (10.2 inches)
Rear Brakes Single disc. Brake calipers on floating bearings
Rear Brake Ø 220 mm (8.7 inches)
Wheels KTM Factory wheels. Wire spoked.
Dimensions & Weight
Dry Weight 100.5 kg (221.6 pounds)
Power/Weight 0.6269 HP/kg
Seat Height 950 mm (37.4 inches) If adjustable, lowest setting.
Fuel Capacity 7.00 litres (1.85 US gallons)
Other
Starter Electric
Color Options Orange/white/black
Electrical Lightweight 495 g lithium-ion starter battery
Notes

Connectivity to a myKTM app

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Before You Compare This Bike

Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.

Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
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Fuel Capacity
Fuel capacity helps estimate touring range and how often you may need to stop.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
Suspension
Suspension details can matter for comfort, road feel and long-distance riding.
Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
Rider Profile

Who Is This Bike For?

🟡
Intermediate
Requires some riding experience.
🌲
Best For
Off-Road & Adventure
📏
Seat Height
95 cm / 37.4 in
⚖️
Handling
Very lightweight — easy to handle
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