The championship winning KTM 450 SX-F is a proven formula that is the industry benchmark. For 2021, this machine continues to deliver superior performance and easy handling. It features an extremely compact, single overhead camshaft cylinder head and together with the efficient electronic fuel injection, it pushes out an unrivalled 63hp in the most effective way possible. The KTM 450 SX-F is simply the fastest Motocross bike out on the track.
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The 450 cc engine is the ultimate powerhouse when it comes to KTM's competitive motocross range. Its compact, lightweight design features a single overhead camshaft cylinder head, fueled by the latest electronic injection system. This enables the impressive 63hp to be distributed extremely efficiently throughout the rev range. Even with its super-beneficial electric starter this model is still the lightest 450 cc engine on the MX market. For 2021, the proven KTM 450 SX-F engine features further developments to improve reliability.
The KTM 450 SX-F is fitted with a lightweight, compact SOHC (single overhead camshaft) cylinder head. The design focusses on mass centralization, contributing to overall handling excellence. The overhead camshaft has a friction-optimized surface and valve timing that delivers impressive responsiveness. The four ultra-lightweight titanium valves (intake 40 mm, exhaust 33 mm) are activated via extremely rigid rocker arms. The rockers on intake side are DLC coated, allowing for impressive engine speeds up to 11,500 rpm. Low-friction chain guides further support the high RPM levels. The innovative head configuration guarantees the most efficient delivery of the unrivalled power, keeping a strong edge over the competition.
The crankshaft on the KTM 450 SX-F is located in an ideal position close to the center of gravity, contributing to better mass centralization. It utilizes a short connecting rod, which allows for a compact motor design and a snappier power delivery. The whole unit is extremely well-balanced, with the perfect amount of inertia for optimal traction and ride-ability. A plain big end bearing with two force-fitted bearing shells, runs directly on the crank pin, with the necessary oil feed for this bearing supplied by the engine's pressure lubrication. This design also enhances durability, allowing for long crankshaft service intervals - resulting in less effort and cost and more time spent on two wheels.
The compact engine cases are manufactured using a high pressure die-cast production process that helps with weight reduction, while retaining strength and durability. The design allows for optimal shaft arrangements close to the center of gravity, resulting in better mass centralization and easier ride-ability. The engine covers feature a smart surface structure that reduces wear caused by the rider's boots, keeping them looking as fresh as the day you bought it.
The transmission on the KTM 450 SX-F is focused on lightweight performance without compromise to durability. There was no need to change the gear ratios as they have been perfectly matched to the power delivery of the large displacement engine, but the secondary drive (sprockets) ratio has been made shorter 13/49 for improved better response. All four-stroke engines are fitted with a gear sensor, which provides the option of different engine characteristics for each gear, depending on engine load. An advanced no-dirt gear lever design prevents dirt from building up and together with the reliable gearbox, guarantees the next gear is always an easy click away.
The state-of-the-art KEIHIN Engine Management System, with electronic fuel injection, features a 44 mm throttle body. The injector position guarantees optimal atomization of the fuel and air on the way to the combustion chamber, resulting in instant response and maximum performance when opening the throttle. There are also separate systems for cold starting and idle adjustment. The ECU features maps which have been developed to precisely match the exhaust and cylinder head, with options for regulating traction and launch control. It also provides different maps for each gear, according to the information received from the gear sensor, ensuring maximum power as you shift through the gears.
The 95 mm bore cylinder houses a newly-shaped, lightweight, piston, made to the very highest standards by CP, delivering improved performance and reliability. Its design contributes to the engine's low vibrations and overall engine speed strength. Due to the low oscillating masses, the engine is not only powerful, but also displays extremely lively characteristics.
The multifunctional side mounted counter balance shaft masterfully balances all the oscillating forces, while also driving the water pump. It effectively keeps engine vibrations to a minimum, resulting in the smoothest ride, even at the highest engine speeds.
The KTM 450 SX-F is fitted with the extremely durable, KTM-developed DDS clutch (damped diaphragm steel), with a wear-free steel basket and heat resistant clutch plates. It uses a diaphragm spring instead of the usual coil springs, which results in considerably easier clutch action. The diaphragm spring is also compact enough to allow for a damping system to be integrated into the clutch hub, contributing to better traction and durability. Additionally, the Brembo S.p.A hydraulic system provides easy and precise clutch modulation.
The standard electric starter on the KTM 450 SX-F uses a proven starter drive and a strong starter motor made by Mitsuba. As demonstrated time and time again, it provides quick and reliable starting, saving you precious time and energy when you need it most.
Within easy reach of the left grip on all four-stroke models, is a multifunctional handlebar map switch, which features the innovative control functions; traction control; launch control and alternative power curves (standard <-> advanced). The TRACTION CONTROL is a unique feature that guarantees more efficient traction and better control when accelerating the bike, especially in challenging track conditions. It can be activated on the handlebar map switch while riding. With a simple push of the two buttons at idle speed, the rider can also activate LAUNCH CONTROL, ensuring the most effective launch out of the gate. The map switch also gives the rider the chance to select an alternative power map besides the standard configuration, providing him with options during the race.
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 450 SX-F features radiators which are positioned for a lower the center of gravity. Their design matches the shrouds perfectly and offers a great slim feel to the ergonomics. By using CFD technology (computational fluid dynamics) together with a clever coolant circuit routing, the innovative system ensures the optimum engine temperature for the highest performance, no matter what the conditions. The radiators also feature special protectors that don't only serve as protection from flying rocks and debris but also as a brace that disperses energy around the radiators in the event of an impact.
When it comes to power delivery and performance, the exhaust on all 4-stroke models plays a key role and packs a punch that is hard to beat. It features a model specific header pipe with an advanced resonator called FDH (Flow Design Header), which is a small chamber around the pipe. The design allows the exhaust to be disassembled without removing the shock absorber and also provides better access to the shock. The aluminum sleeve, end cap and internal design of the silencer allows for slimmer ergonomics, making the bike feel narrower, without compromise to regulatory noise limits.
The new aggressive-looking graphics were designed to send a clear message to the competition that this is not a bike that should be taken lightly.
All SX-F models feature a capable, super lightweight 2 Ah Lithium-Ion starter battery, ensuring quick and effective starting of the engine, especially in cold weather conditions. The voltage regulator and condenser, as well as all the electrical components are packaged in a common area below the seat, making the entire system compact and reliable.
TRACTION CONTROL is a highly beneficial feature that guarantees more efficient traction and better control of the bike when accelerating on wet or slippery hard pack surfaces. It can be activated by the handlebar map switch during riding.
By pushing both buttons on the map switch, the rider can activate LAUNCH CONTROL, which ensures a more efficient launch out of the start gate. It reduces the maximum engine speed for the very first moment of the start to give better control. The EFI control lamp mounted on the upper triple clamps flashes when the function is active.
With one touch of a button, the map switch gives the rider the chance to select between a standard map setting and a more aggressive map for loamy, high grip dirt conditions. This is particularly useful for changing track conditions or for a rider that is looking for more control as he begins to fatigue.
As with the entire KTM SX range, the frame on the KTM 450 SX-F is professionally crafted from hydro-formed chromium molybdenum steel tubes that are robot welded to ensure the highest levels of consistent quality. The precisely calculated stiffness of the frame delivers responsive handling and works perfectly with the suspension to provide excellent agility and high-speed stability. All 2021 KTM SX frames feature a highly durable powder coating and come with standard frame protectors. The subframe is made from lightweight aluminum and provides great feeling for the rider, as well as easy movement across the seat.
The KTM 450 SX-F's one-piece swingarm, is manufactured using a gravity die-cast production process, for exceptional strength at the lowest possible weight. It offers a wide range of adjustment for the rear wheel, allowing for a shorter wheelbase on tighter twisty tracks, or a longer wheelbase for greater stability on longer, more choppy tracks. The swingarm's chain measurement markings are visible from above, making adjustment simpler and more accurate.
KTM uses lightweight, CNC-machined hubs and high-end Excel rims on all SX models, guaranteeing maximum stability and minimum weight. The aluminum spoke nipples feature a design that conveniently reduces the frequency with which the spokes need to be tightened. The wheels are fitted with the latest Dunlop Geomax-MX33 tires, delivering maximum grip and stability, effectively transferring all the power to the ground.
All full-size KTM SX models are fitted with the super-lightweight WP XACT fork with AER technology and feature updated settings for 2021. It is a 48 mm USD air-sprung fork with separate functions in each fork leg, with damping functions on the right side and the air spring on the left. The left leg features a two-chamber system with a capsuled air cartridge, helping prevent loss of air pressure. Essentially, this means that in the rare case of a leaking outer seal, the internal cartridge pressure keeps the bike in a normal position. The air spring is exceptionally easy to use and can be adjusted to any rider weight via a single air valve and the air pump that is supplied with the bike. The right fork leg integrates a damping cartridge to fit single damping leg requirements and can be adjusted to the track conditions and the rider's preferences. Additionally, the fork top caps have a new design for improved, easy adjustment (compression) from top, rebound from bottom, 30 clicks each).
All KTM SX models feature a WP XACT monoshock, which has been developed to work as a complete unit with the entire frame and swingarm architecture, as well as the linkage system and the WP XACT AER fork. It features high-quality machined and anodized components, which add a touch of class and give it appeal beyond just a functional necessity. It is fully adjustable, including high and low speed compression, allowing you to set the shock up precisely to suit any track and rider's preferences.
All KTM SX models feature top quality, CNC-machined triple clamps which have become a KTM trademark. The triple clamp has a precisely calculated stiffness and offset (22 mm offset for all models) to match the flex characteristics of the frame and fork. The result is a front end that all works in perfect harmony, contributing positively to the overall handling and stability. The rubber damped handlebar fixation reduces vibration and also allows for some adjustment with 2 different mounting positions. An hour meter is fitted as standard on the upper triple clamp on all SX models, keeping the rider informed of the number of hours spent tearing up the track and when the next service is due.
High-tech Brembo S.p.A brakes have always been standard equipment on all KTM motocross bikes. Combined with lightweight wave discs, the renowned system provides the highest level of braking efficiency, enabling you to out-brake the competition.
All models in the KTM SX range are fitted with lightweight polyethylene fuel tanks. The shape of the fuel tank allows for slim ergonomics without compromise to the 7 liter fuel capacity. The filler cap has an inside thread that makes for easy and reliable closure.
The airbox on the KTM 450 SX-F ensures optimal flow dynamics, and together with its intake snorkels, leads to maximum power and quick throttle response. Despite the obvious performance advantages, the design also offers maximum protection against soiling of the air filter. The large Twin-Air air filter is mounted on a cleverly designed stiff cage that minimizes incorrect installation. As found on previous models, filter maintenance is quick and easy and does not require tools - a standard, original feature from KTM.
All KTM SX models feature a seat that perfectly matches the range's dynamic performance-oriented ergonomics. The seat cover features silicone strips that provide better feel and grip for the rider. The seat is conveniently fixed to the bike using one long, lateral screw, making it secure and easy to handle.
All KTM SX models feature a seat that perfectly matches the range's dynamic performance-oriented ergonomics. The seat cover features silicone strips that provide better feel and grip for the rider. The seat is conveniently fixed to the bike using one long, lateral screw, making it secure and easy to handle.
Sophisticated ´no-dirt´ footpegs prevent clogging of the footpeg pivot, even when digging in deep ruts. Looking for a higher riding position? Then just mount the footpegs of the 2019 EXC models, which are 6mm higher than the SX versions.
| ENGINE | |
|---|---|
| TRANSMISSION | 4-speed |
| STARTER | Electric starter |
| STROKE | 63.4 mm |
| BORE | 95 mm |
| CLUTCH | Wet, DDS multi-disc clutch, Brembo hydraulics |
| DISPLACEMENT | 449.9 cm³ |
| EMS | Keihin EMS |
| DESIGN | 1-cylinder, 4-stroke engine |
| CHASSIS | |
|---|---|
| WEIGHT (WITHOUT FUEL) | 100 kg |
| TANK CAPACITY (APPROX.) | 7 l |
| FRONT BRAKE DISC DIAMETER | 260 mm |
| REAR BRAKE DISC DIAMETER | 220 mm |
| FRONT BRAKE | Disc brake |
| REAR BRAKE | Disc brake |
| CHAIN | 5/8 x 1/4" |
| FRAME DESIGN | Central double-cradle-type 25CrMo4 steel |
| FRONT SUSPENSION | WP XACT-USD, Ø 48 mm |
| GROUND CLEARANCE | 370 mm |
| REAR SUSPENSION | WP XACT Monoshock with linkage |
| SEAT HEIGHT | 955 mm |
| STEERING HEAD ANGLE | 63.9 ° |
| SUSPENSION TRAVEL (FRONT) | 310 mm |
| SUSPENSION TRAVEL (REAR) | 300 mm |
