Engine: The hugely successful KTM 450 SX-F powerhouse has extremely compact dimensions, strong performance throughout the rev range and a low weight; this is the lightest 450 engine on the MX market. But that doesn’t mean it’s not a heavyweight in terms of muscle. Fitted with a single overhead camshaft cylinder head and the latest electronic fuel injection, it pumps out unrivaled horsepower. With KTM’s engineers working tirelessly to increase the ultimate READY TO RACE machine, this powerhouse has the latest engine management technology on board and confidently shoots both amateurs and pros to the top of their time sheets.
Cylinder Head: Inside the SOHC cylinder head, an overhead camshaft controls four ultra-lightweight titanium valves via extremely rigid rocker arms, which are DLC-coated on the intake side. A configuration like this allows engine speeds of up to 11,500rpm; a baffling figure for a large displacement thumper. New lateral brackets, made of aluminum instead of steel, allow an efficient fixation of the engine to the frame and contribute to the bike’s featherweight feel.
Crankshaft: The 450 SX-F’s crankshaft utilizes a short connecting rod, which makes for an overall compact and lightweight engine with a snappy power delivery. A plain big-end bearing with two force-fitted bearing shells runs directly on the crank pin. The necessary oil feed for this bearing is ensured by the engine’s pressurized lubrication. This design is a decisive benefit in terms of the crankshaft service interval, which can be lengthened due to the plain bearing. So just pin it, all day long.
Crankcases and Covers: The design of the die-cast engine cases allows for minimal weight and a very centralized shaft configuration. This makes the engine short and compact, while contributing to an efficient centralization of masses. The engine covers also feature a solid surface structure, which reduces the wear caused by the rider’s boots. This way, your SX-F will keep looking better longer.
Transmission: The KTM 450 SX-F uses a lightweight 5-speed transmission with gear ratios that are perfectly matched to the power delivery of its large displacement engine. The 1st and 3rd gears are treated with a special surface coating for better reliability. An advanced ´No Dirt´ gear shift lever design prevents mud and sand from blocking the joint of the lever and guarantees trouble-free shifting. All 4-stroke engines are fitted with a gear position sensor, giving the option of different engine characteristics for each gear. For 2018, the transmission shaft gets a stronger shifting star and a C4 bearing that has a bigger overlap in the case. This guarantees better reliability even in extremely tough operating conditions.
Engine Management System: The state-of-the-art Keihin Engine Management System with electronic fuel injection features a 44mm throttle body. Thanks to its unique injector position, the engine’s response is instantaneous. And to make life even easier, separate systems for cold starts and idle adjustment await you. The lightweight ECU features a unique traction and launch control system for lightning-quick response when the gate drops and maximum grip thanks to different maps that sync with to the gear you’re in. It’s also possible to unleash an even more powerful mapping via the handlebar map switch.
Cylinder and Piston: Inside the short cylinder, with a bore of 95mm, thumps a box-type piston made by CP. Its crown geometry is adapted perfectly to the high-compression combustion chamber, where its rigid structure and low weight shine. Thanks to the low oscillating masses, the engine is as snappy as it is strong.
Balancer Shaft: The side-mounted counter balancer does double duty also driving the water pump. Thanks to its perfect balance and low oscillating masses, engine vibration is kept to a minimum.
Clutch: The 450 SX-F employs the KTM-developed DDS clutch (damped diaphragm steel) with a wear-free steel basket and extremely heat resistant clutch plates. This clever design employs a diaphragm spring instead of the usual coil springs, making for considerably easier clutch action. A diaphragm spring also leaves sufficient space for a damping system to be integrated into the clutch hub. The goal is traction, but durability is as well. A lighter basket, a reworked inner hub and a pressure plate providing better oil supply and unsurpassed cooling up the longevity of the DDS clutch. Light operation and telepathic amounts of control are standard with this hydraulic Brembo actuated clutch.
E-Starter: The KTM 450 SX-F is fitted with a unique E-starter as standard, which is a clear advantage when it comes to crunch time in the heat of battle. A strong starter motor made by Mitsuba will fire time and time again at the push of a button.
Cooling System: KTM’s proven cooling system routes the coolant from the cylinder head through the frame triangle, directly to aluminum radiators made by WP. A new filler cap system and are stiffer alloy construction increase the durability and reliability of the cooling system. Due to flow optimized internal circulation and CFD-calculated air ventilation, the system is superbly efficient. In addition, well thought-out radiator guards integrated in the front part of the shrouds provide protection in a crash.
A Dancer in the Dirt
Weight: KTM engineers just love dropping weight year after year. The result: the 2018 KTM SX models are the slimmest, lightest dirt bikes out there. Even though the 4-strokes are equipped with an E-starter as a standard feature, while the heavier competition still needs to be kickstarted. You can just focus on kicking ass.
Frame: The high-tech, lightweight chrome-moly steel frame has a knack for easy handling, outlandish rideability, precise cornering and excellent stability. You can also count on high torsional rigidity and low longitudinal stiffness. This results in better absorption of the energy created from the front and rear suspension, sucking up jumps and bumps. In short: more comfort and less rider fatigue. Laterally attached, lightweight aluminum engine head stays (the connection between cylinder head and frame) contribute to more precise cornering and a reduced vibration level. The engineers were able to pull off all that, while making their frame 2.2 pounds lighter than that of the lightest competitor on the market. In addition, it is easier to maintain, easier to work on and supplies more space for the tank and other components. The bike also features an extra-light subframe made of aluminum, which tips the scales at less than 2 pounds.
Footpegs: 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 2018 EXC models, which are 6mm higher than the SX versions.
Air Filter Box: The airbox design offers maximum protection of the air filter while ensuring maximum airflow. The large twin-air filter is mounted in a stiff cage, which at the same time holds the system in place. This design is so simple, you could still pop a fresh one in with a face full of mud. Without tools. In seconds.
Exhaust System: Competition noise limits are a real challenge for every manufacturer. Therefore, KTM has put a lot of effort into the development of their exhaust systems. All 4-strokes are fitted with headers that have a unique standard feature; an additional resonator system – a small chamber connected to the pipe. All 4-strokes are fitted with a short silencer, mounted as close to the engine as possible. You know what that means: extra mass centralization and better rideability. Its advanced internal design reduces the noise sufficiently in order to sit safely below the noise limit, while still raising the hairs on your neck.
Handlebar: KTM engineers sure know how to handle handlebars. This tapered one, made of high-strength aluminum by NEKEN, is fixed in damped rubber mounts and has two different positions. From 2017 onwards, the lower handlebar clamps are separated, while on the upper side a new bridge-type clamp guarantees more torsional stiffness. It’s also easier to replace the bar in case it gets twisted in a nasty crash. ODI lock-on grips make grip changes easy which does not require any wire or glue to be secured.
Swingarm: The cast aluminum design offers low weight and a perfect flex behavior. The single-component casting process eliminates any inconsistencies and inherent weak points created by welding. It’s better looking too.
Fuel Tank: A lightweight polyethylene tank with a capacity of 1.85 gallons. The fuel tank cap has an inside thread, which makes for easy and reliable closure.
Wheels: Featuring lightweight, CNC machined hubs and high-end Excel rims, they guarantee maximum stability and minimal unsprung weight. The wheels are shod with the latest Dunlop Geomax MX 3S tires for exceptional handling.
Float Like a Butterfly
Shock Absorber: The WP shock absorber has been developed with the entire frame and swingarm architecture in mind, including the linkage system and the WP AER 48 front forks. It features machined and black anodized components and is a valuable, high-end product compared to roughcast reservoirs. A new, confidence inspiring setting with improved damping characteristics perfectly matches the front-end set-up and its WP color scheme lets everyone know you have excellent taste in suspension.
Fork: The lightweight WP AER 48 front fork, a 48mm USD air-sprung fork developed by WP in close collaboration with KTM, is a split fork with separate functions for each leg. That means damping functions are on the right side, whereas the air spring is in the left. This left leg features a 2-chamber system with a capsuled air cartridge to prevent loss of air pressure. Should the outer seal start to leak, the internal cartridge pressure will keep the bike in position. The air spring is easy to adjust to any rider weight via a single air valve. No extra special tools are required; the fork air pump is supplied with the bike. The right fork leg integrates a damping cartridge that tailors to all your damping needs. It can be adjusted to the track conditions and the rider’s preferences with a twist of a dial (compression from the top, rebound from the bottom, 30 clicks each). Right off the dealer floor, this fork (with reworked damping characteristics) is more comfortable and more sensitive than ever. But you can still hammer the hell out of it.
Triple Clamp: Top quality, CNC machined triple clamps have been a KTM trademark for years to ensure precise handling. For 2017, the upper triple clamp specifically features a redesign in conjunction with the new fork tubes. The rubber damped handlebar mount has also been reworked and the lower handlebar clamps are now separated, while on the upper side a new bridge-type clamp guarantees more torsional stiffness and can easily be replaced in case it gets twisted due to a crash. In addition, an hour meter is fitted at the upper triple clamp in order to let the rider know it’s time for a service.
Brakes: You can’t brake any harder, better, faster or stronger. These high-tech Brembo babies are combined with lightweight wave discs made by Galfer. For 2017, the rear brake features a 10mm longer brake pedal and you get new, less aggressive brake pads all round.
Handlebar Map Select Switch: All 4-stroke models are equipped with a sophisticated new multi-functional handlebar map select switch, which does three things:Activation of the traction controlActivation of the launch controlSelection of two power curves (Standard or Advanced)The traction control is a unique feature that none of the competitors can offer. It guarantees more efficient traction when the track conditions are less than perfect. Push the button and reign supreme. With this map select switch the rider can also activate the launch control, which provides more efficient starts out of the gate so you can go for the holeshot, time and time again. How? It simply reduces the maximum engine speed for the very first moments of the start, in order to give you better control. Push both buttons when the engine idles and the EFI control lamp mounted on the upper triple clamps will let you know you are READY TO RACE. In addition, the map select switch gives the rider the chance to select an alternative, more powerful map beside the standard configuration. Welcome to the future.
Battery & Wiring Harness: A strong new lithium ion battery breathes life into the engine and contributes to low vehicle weight. The lightweight battery and wiring harness are centralized in a compartment above the air filter box, allowing the mechanic to remove the subframe without moving the electronics. A happy mechanic is a good mechanic.
E-Starter: Like all KTM 4-stroke motorcycles, the 450 SX-F is started at the push of a button - a priceless advantage when you’re on the clock.
King of Cool
Bodywork: KTM R&D, KISKA Design and all our factory riders had their say in shaping the plastics with one goal: complete harmony between rider and bike. Perfect ergonomics and contact points provide maximum comfort in movement on the SX-F. The I-beam structures of the front and rear fenders guarantee maximum stability and a low weight thanks to well thought-out construction and mounting. They also stay cleaner for longer.
Graphics: A new, tailor-made kit and a Factory orange frame. Because in this sport, champs deserve to look the part regardless of the dirt.
Design: 1-cylinder, 4-stroke engine
Displacement: 449.9 cm³
Bore: 95 mm
Stroke: 63.4 mm
Starter: Electric starter
Primary drive: 31:76
Secondary gear ratio: 13:48
Clutch: Wet, DDS multi-disc clutch, Brembo hydraulics
EMS: Keihin EMS
Frame design: 25CrMo4 steel central-tube frame
Front suspension: WP-USD, AER 48, Ø 48 mm
Rear suspension: WP shock absorber with linkage
Suspension travel (front): 12.2 in.
Front brake: Disc brake
Rear brake: Disc brake
Front brake disc diameter: 260 mm
Rear brake disc diameter: 220 mm
Chain: 5/8 x 1/4 in.
Steering head angle: 63.9 deg.
Seat height: 37.8 in.
Weight READY TO RACE (pound) (without fuel): 220.9 lb.
Suspension travel (rear): 11.81 in.
Tank capacity (approx.): 1.85 US gal.