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2021 KTM 450 SX-F Overview
For 2021, KTM offers the 450 SX-F as a cross / motocross motorcycle with 449.3 cc on tap. The 2021 KTM 450 SX-F is built around a Single cylinder, four-stroke engine running Single Overhead Cams (SOHC) valve actuation. Internally, bore and stroke are 95 x 63.4 mm. In everyday use, the 2021 450 SX-F tips the scales at 100 kg, carries a 7-litre fuel tank, offers a seat height of 950 mm and spans a 1485 mm wheelbase. Every technical detail, from suspension travel to tyre sizes, is covered in the full 2021 KTM 450 SX-F spec sheet below.
2021 KTM 450 SX-F compared with other bikes in the Cross / motocross category
Measured against other bikes in the Cross / motocross category in our database (up to 224 models, one entry per model), the 2021 KTM 450 SX-F comes out as follows.
- With 449 cc, the 450 SX-F has the joint 41st largest engine displacement of 224 bikes in the Cross / motocross category, 61% above the category average of 279 cc.
- Seat height of 950 mm is taller than that of 122 of the other 199 bikes in the Cross / motocross category.
- Narrowing the field to the 94 models within five model years of it, the engine displacement of 449 cc is larger than that of 78 of the other 93.
Versus the 2020 model
The figures we track are unchanged from the 2020 model: displacement and seat height all match.
2021 450 SX-F - Pros & Cons
Strengths
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🔧
Fuel injection: No choke, no jetting, no altitude compensation to think about - fuel injection just works across a wider range of conditions than carburetion.
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🛑
Strong front braking: The single disc front brake bites hard and stays consistent - a solid foundation whether it's stock or upgraded with braided lines.
Considerations
-
📏
Tall seat height: A 950 mm seat puts flat-footing out of reach for a lot of riders - sit on it in person before committing.
-
⛽
Modest fuel capacity: A 7-litre tank keeps things light but means budgeting for more frequent fuel stops on any longer ride.
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⚙️
Chain final drive upkeep: A chain drivetrain is the most common setup in its class, but it's also the one that demands the most regular hands-on maintenance.
Wear Points & Servicing Notes
Fuelling & injector care
Fuelling on the 450 SX-F comes from fuel injection. Cold starts and throttle response stay consistent across altitude and temperature, the main practical edge over a carbureted equivalent.
Valve clearance checks
Valve clearances on Single Overhead Cams (SOHC)-equipped engines like the 450 SX-F's drift slowly with mileage rather than failing suddenly - sticking to the service interval keeps it a non-issue.
Brake disc and pad wear
Single disc with Brake calipers on floating bearings up front provides the primary stopping power; inspect disc thickness and pad wear at each tyre change to catch scoring before it becomes a rotor replacement.
Suspension condition on used examples
Suspension duties are handled by WP XACT-USD, Ø 48 mm up front and WP XACT Monoshock with linkage at the rear. Weeping fork seals aren't a dealbreaker on a used bike, but they're a fair basis for negotiating price.
Final drive maintenance
Chain final drive on the 450 SX-F means routine lubing and tension checks are part of ownership - skip them and sprocket wear accelerates noticeably.
Frame & chassis check
The 25CrMo4 steel central-tube chassis holds up well with normal use; on a used bike it's still worth checking the head-stock and swingarm pivot area for impact damage or corrosion.
Low-speed handling
The 450 SX-F's 100 kg kerb weight makes low-speed control noticeably less effort than on a heavier machine.
450 SX-F - Buying & Maintenance Guide
What to check before buying
A pre-purchase check on the 2021 KTM 450 SX-F with its 449.3 cc cross / motocross should cover the same ground every time: service history, drivetrain condition, and any oil seepage around the casings. This model runs chain final drive, so check chain slack and sprocket tooth profile specifically - a worn sprocket is a cheaper fix now than after it's chewed up the next chain. Now 5 years old, this cross / motocross is as likely to show age-related wear (perished rubber, seized fasteners, degraded seals) as mileage-related wear. Start it from cold if you can - a well-kept 450 SX-F settles to a smooth idle within seconds.
Oil and filter changes
Oil changes are the cheapest insurance you can buy for the 450 SX-F's 449.3 cc single cylinder, four-stroke - keep to the manufacturer's interval rather than stretching it. Use the viscosity grade the manual specifies, not whatever's on sale.
Fuel system care
Injector systems like the 450 SX-F's hold up well with basic care - decent fuel, an occasional cleaner additive, and draining old fuel before any layup longer than three months.
Valve clearance service
There's no reliable seat-of-the-pants way to tell if a 450 SX-F's valve clearances are in spec - a light top-end tick is the only real warning sign, and by then some wear has already happened. Service records are the only proof.
2021 KTM 450 SX-F - Frequently Asked Questions
What engine does the 2021 KTM 450 SX-F have?
The 2021 KTM 450 SX-F uses a Single cylinder, four-stroke engine with 449.3 cc of displacement.
How much does the 2021 KTM 450 SX-F weigh?
The 2021 KTM 450 SX-F weighs 100 kg. This is the manufacturer's dry figure.
What is the fuel tank capacity of the 2021 KTM 450 SX-F?
The 2021 KTM 450 SX-F has a 7-litre fuel tank. At around 5-6 litres per 100 km, that is roughly 116-140 km between stops.
Is the 2021 KTM 450 SX-F suitable for shorter riders?
The 2021 KTM 450 SX-F has a seat height of 950 mm. This is towards the tall end of the spectrum and will require most riders under 175 cm to tiptoe at stops.
What brakes does the 2021 KTM 450 SX-F have?
The 2021 KTM 450 SX-F uses single disc with Brake calipers on floating bearings at the front and single disc with Brake calipers on floating bearings at the rear.
What fuel system does the 2021 KTM 450 SX-F use?
The 2021 KTM 450 SX-F uses Injection, providing precise fuelling across the rev range and reliable cold-start behaviour.
What suspension does the 2021 KTM 450 SX-F have?
The 2021 KTM 450 SX-F uses WP XACT-USD, Ø 48 mm up front and WP XACT Monoshock with linkage at the rear.
KTM 450 SX-F Spec Evolution
The KTM 450 SX-F was produced across 16 model years (2007-2023). The table below highlights the key specifications that changed across the production run - useful whether you are comparing years or tracking down a specific variant.
| Specification |
2007 |
2008 |
2009 |
2010 |
2011 |
2012 |
2013 |
2015 |
2016 |
2017 |
2018 |
2019 |
2020 |
2021 |
2022 |
2023 |
| Dry Weight |
104 kg / 229.3 lbs |
104.6 kg / 230.6 lbs |
104.6 kg / 230.6 lbs |
104.6 kg / 230.6 lbs |
106.9 kg / 235.7 lbs |
107.8 kg / 237.7 lbs |
106.2 kg / 234.1 lbs |
105.5 kg / 232.6 lbs |
100.4 kg / 221.3 lbs |
100.2 kg / 220.9 lbs |
100.2 kg / 220.9 lbs |
100 kg / 220.5 lbs |
100 kg / 220.5 lbs |
100 kg / 220.5 lbs |
100.5 kg / 221.6 lbs |
102.6 kg / 226.2 lbs |
| Engine Type |
Single cylinder |
Single cylinder |
Single cylinder |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
Single cylinder, four-stroke |
| Seat Height |
925 mm / 36.4 in. |
960 mm / 37.8 in. |
985 mm / 38.8 in. |
985 mm / 38.8 in. |
992 mm / 39.1 in. |
992 mm / 39.1 in. |
992 mm / 39.1 in. |
992 mm / 39.1 in. |
960 mm / 37.8 in. |
960 mm / 37.8 in. |
960 mm / 37.8 in. |
960 mm / 37.8 in. |
950 mm / 37.4 in. |
950 mm / 37.4 in. |
950 mm / 37.4 in. |
958 mm / 37.7 in. |
| Fuel Capacity |
8.00 litres / 2.11 gallons |
8.20 litres / 2.17 gallons |
8.00 litres / 2.11 gallons |
8.00 litres / 2.11 gallons |
7.50 litres / 1.98 gallons |
7.50 litres / 1.98 gallons |
7.50 litres / 1.98 gallons |
7.50 litres / 1.98 gallons |
7.00 litres / 1.85 gallons |
7.00 litres / 1.85 gallons |
7.00 litres / 1.85 gallons |
7.00 litres / 1.85 US gallons |
7.00 litres / 1.85 US gallons |
7.00 litres / 1.85 US gallons |
7.50 litres / 1.98 US gallons |
7.20 litres / 1.90 US gallons |
| Bore x Stroke (in,) |
3.8 x 2.4 inches |
3.8 x 2.4 inches |
3.8 x 2.4 inches |
3.8 x 2.4 inches |
3.8 x 2.4 inches |
3.8 x 2.4 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
3.7 x 2.5 inches |
| Bore x Stroke (mm) |
97.0 x 60.8 mm |
97.0 x 60.8 mm |
97.0 x 60.8 mm |
97.0 x 60.8 mm |
97.0 x 60.8 mm |
97.0 x 60.8 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
95.0 x 63.4 mm |
| Displacement (cc) |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.30 cc |
449.3 cc |
449.3 cc |
449.3 cc |
449.3 cc |
449.9 cc |
| Displacement (ci) |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.42 cubic inches |
27.45 cubic inches |
Key Specifications
Engine
Single cylinder, four-stroke
Weight
100 kg / 220.5 lbs
Fuel Capacity
7.00 litres / 1.85 US gallons
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Full 2021 KTM 450 SX-F Specifications
Colours
Orange/white/black
Ground Clearance (in.)
14.6 inches
Ground Clearance (mm)
370 mm
Seat Height
950 mm / 37.4 in.
Wheelbase
1485 mm / 58.5 in.
Dry Weight
100 kg / 220.5 lbs
Fuel Capacity
7.00 litres / 1.85 US gallons
Bore x Stroke (in,)
3.7 x 2.5 inches
Bore x Stroke (mm)
95.0 x 63.4 mm
Displacement (cc)
449.3 cc
Displacement (ci)
27.42 cubic inches
Engine Type
Single cylinder, four-stroke
Fuel Control
Single Overhead Cams (SOHC)
Fuel System
Injection
Ignition
Keihin EMS
Starter
Electric
Clutch
Wet, DDS multi-disc clutch, Brembo hydraulics
Final Drive
Chain (final drive)
Gearbox
4-speed
Primary Drive
5/8 x 1/4
Frame Type
25CrMo4 steel central-tube
Suspension - Front
WP XACT-USD, Ø 48 mm
Suspension - Rear
WP XACT Monoshock with linkage
Rake
26.1°
Wheel Travel - Front
310 mm / 12.2 in.
Wheel Travel - Rear
300 mm / 11.8 in.
Brakes - Front
Single disc. Brake calipers on floating bearings
Brakes - Rear
Single disc. Brake calipers on floating bearings
Rims
CNC machined hubs. Excel rims. Wire spoked.
Specifications are compiled from manufacturer documentation and cross-referenced
technical sources, and corrected on an ongoing basis.
Spot an error? Let us know.
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