Engine: The KTM 250 SX-F engine is known to be the strongest engine in the 250cc class. It screams at the top of its lungs at 14,000rpm, but is equally happy producing tons of torque and power across the rest of the rev range. Its compact architecture contributes to an excellent mass centralization, supporting the rideability of the bike. And it only weighs 47.6 pounds. That’s including the incredibly beneficial E-starter.
Cylinder Head: The centerpiece of the compact DOHC engine is the cutting-edge cylinder head. It features two overhead camshafts, which activate the titanium valves via super-light finger followers with a hard DLC coating. New lateral brackets (now made of aluminum instead of steel) allow an efficient fixation of the engine to the frame and shave off even more weight.
Crankshaft: The 250 SX-F has an extremely rigid crankshaft, which features a connecting rod with a plain big end bearing with two force-fitted bearing shells running directly on the crank pin. This design is a major prerequisite for the extremely high engine speed levels and the unrivaled maximum power of the 250cc engine. Not only that, it enhances the engine’s durability, allowing long crankshaft service intervals, which is a huge customer benefit in relation to time, effort and cost.
E-Starter: The 250 SX-F is fitted with an electric 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 and the proven starter drive will fire time and time again at the push of a button.
Crankcases and Engine 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 reliable 5-speed transmission features a special surface treatment on the 2nd, 3rd and 4th gears for solid reliability. The advanced ´No Dirt´ gear shift lever design prevents dirt from jamming the joint of the lever and guarantees precise shifting even in the muddiest conditions. All 4-stroke SX-F engines are fitted with a gear position sensor for tailored engine mapping for each gear. For 2018, the transmission shaft gets a new C4 bearing that has a bigger overlap in the case. This means reliability even under extremely hard 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 78mm, thumps a box-type piston made by CP. Its crown geometry is adapted perfectly to the high-compression combustion chamber (14:1), where its rigid structure and low weight shine. Thanks to the low oscillating masses, the engine is 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 KTM 250 SX-F employs the KTM-developed CSS clutch (coil spring steel) with a robust steel basket and extremely heat resistant clutch plates and new, nitrated steel liners reducing the wear. Light operation and telepathic amounts of control are standard with this hydraulic Brembo actuated clutch.
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.
Born For This
Weight: The main target for the KTM engineers when developing the SX models was a massive weight reduction compared to the previous generation. The result: the current SX-F models are the slimmest, lightest bikes on the track. Even though the 4-strokes are equipped with an electric starter as a standard feature, while the competition still needs to be kick started, the SX-F line weigh in pounds less. Rather than kicking to start - you can 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: Noise limits are a real challenge for every manufacturer. Therefore, KTM has put a lot of effort into the development of its exhaust systems. All 4-strokes are fitted with header pipes 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 for mass centralization and better rideability. Its advanced internal design reduces the noise sufficiently in order to sit safely below noise limits while still raising the hairs on your neck.
Handlebar: KTM engineers sure know how to handle handlebars. This tapered unit, made of high-strength aluminum, is fixed in damped rubber mounts and has two different positions. ODI lock-on grips make grip changes easy and do 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 as well.
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: The KTM wheels feature lightweight, CNC machined hubs and high-end Excel rims guaranteeing maximum stability at minimum weight. The wheels are fitted with the latest Dunlop Geomax MX 3S tires. This set is now wider at the rear (110/90-19 instead of 100/90-19) and the bike gets an optimized gearing (14/51 instead of 13/50).
Shock Absorber: The WP shock absorber has been developed with the entire frame and swingarm architecture in mind, including the linkage and the WP AER 48 front fork. 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 setup 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 special tools are required; the 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 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 clamp 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.
Bodywork: KTM R&D, Kiska Design and the factory racers 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: New graphics convey the READY TO RACE character of the SX-F model line.