2017 KTM 250 SX-F
The 250 SX-F has been on top of the MX2 World Championship for many years now and added a second AMA Supercross Lites Championship to its crowded trophy cabinet. But that’s no surprise. The successful combination of a powerful and torquey engine in a lightweight and agile chassis is bound to place the 250 SX-F onto podium after podium.
- Engine: The 250 SX-F engine is known to be the strongest engine in the MX2 paddock. 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 26.1kg. That’s including the incredibly beneficial electric starter. David, meet Goliath.
- Cylinder Head: The centerpiece of the compact DOHC (double overhead camshaft) 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 another couple of hundred grams.
- Crankshaft: The 250 SX-F has a rigid crankshaft, which features a connecting rod with a plain big end bearing featuring two force-fitted bearing shells run 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 250cm3 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.
- Electric Starter: The 250 SX-F is fitted with a unique 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 up your track star time and time again at the push of a button.
- Engine Cases and Covers: The design of the die-cast engine cases minimizes weight and allows for 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 that reduces the wear caused by the rider’s boots. Brilliant.
- Transmission: The engine is fitted with a smooth 5-speed gearbox, which features a special surface treatment on the 2nd, 3rd and 4th gears for best reliability. The advanced ´No Dirt´ gear lever design prevents dirt from blocking the joint of the lever and guarantees a safe activation of the transmission. All 4-stroke engines are fitted with a gear sensor to give the option of different engine characteristics for each gear.
- 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 bar drops and maximized grip thanks to different maps that sync with to the gear you’re in. As an ultimate bonus, the rider can 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 as cheerful as it’s strong.
- Counter Balancer Shaft: In order to balance the mass-forces, the 250 SX-F engine uses a multifunctional counter balance shaft, which at the same time drives the water pump and timing chain. Win, win, win!
- Clutch: The highly compact CSS clutch (coil spring steel) features a wear-free steel basket fitted with seven clutch plates, which are extremely heat resistant due to their steel carrier discs. The Brembo hydraulic system provides easy and precise modulation.
- 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. 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 spoilers provide protection in case of crashes.
- 98.2 kg: 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 in the competition, even though the 4-strokes are equipped with an electric starter as a standard feature, while the competition still needs to be kick started. 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 a big fat kilogram 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 stable aluminum profiles, which tiptoes the scales at less than 900g.
- Footpegs: Sophisticated ´No Dirt´ footpegs prevent smudging up the pegs, even when digging in deep ruts. Looking for a higher riding position? Then just mount the footpegs of the MY2017 EXC models, which are 6mm higher than the SX versions.
- Airbox: The airbox design offers maximum protection of the air filter against soiling, 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: FIM 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 header pipes that have a unique standard feature; an additional resonator system – a small chamber connected to the pipe. On top of that, they get a short silencer, mounted as close to the engine as possible. You know what that means: extra mass centralization and better rideability. An advanced internal design reduces the noise sufficiently in order to sit safely below the FIM noise limit (112 dB(A) at 2 meter max.), 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 mountings and has two different positions. From MY2017 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. An ODI volcanized grip sits on the right, while on the left side of the bar a comfortable ODI lock-on grip is mounted, which does not require any wire or glue to be fixed.
- 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 7.0 liters of juice. The filler 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 secondary drive (14/51 instead of 13/50).
- Seat: Tailored to meet the needs of the world’s fastest backsides, this durable seat offers great comfort. For MY2017, a new cover pampers its riders even more with better feel and grip.
- Monoshock: The WP monoshock 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 setting and a softer spring perfectly match the reworked front-end set-up and its sparkling WP color scheme lets everyone know you have excellent taste in suspension.
- Forks: 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 two-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 supplied with the bike will do just fine. 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). For MY2017, the AER 48 also features redesigned outer tubes with better bending characteristics, smoother operation and less friction. Plus: they’ve lost some weight (265g). Right off the dealer floor, these forks are more comfortable and more sensitive than ever. But you can still hammer the hell out of them.
- Triple Clamp: Top quality, CNC machined triple clamps have been something of a KTM trademark for years. Ensuring a precise handling, they perceptibly support the flex characteristics, and with it the action of the forks. For MY2017, the upper triple clamp specifically features a redesign in conjunction with the new fork tubes. The rubber damped handlebar fixation 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. Or a cold drink.
- Brakes: You couldn’t brake any harder, better, faster or stronger. These high-tech Brembo babies are combined with lightweight wave discs made by Galfer. For MY2017, the rear brake features a 10mm longer brake pedal and you get new, less aggressive brake pads all round.
- Handlebar Map Switch: All 4-stroke models are equipped with a sophisticated new multi-functional handlebar map switch, which does three things: Activation of the traction control; Activation of the launch control; Selection of an alternative power curve (Standard or Advanced),The traction control is a unique feature none of the competitors can offer so far. It guarantees more efficient traction and better control of the bike when accelerating. You’ll especially notice this on a rainy day. Push the button and reign supreme. With this map 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 moment 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 your bomb is live. In addition, the map switch gives the rider the chance to select an alternative, more powerful map beside the standard configuration. Don’t you just love the idea of a boost button?
- Battery & Wiring Harness: All SX-F engines are fitted with the proven electric starter – a unique KTM feature and a major benefit at all levels of motocross racing. A super compact and lightweight 495g Lithium-Ion starter battery breathes life into the engine and contributes to low vehicle weight. The battery and wiring harness are centralized in a compartment above the airbox, allowing the mechanic to remove the subframe without getting in conflict with the electrics. Because a happy mechanic, is a good mechanic.
- Electric Starter: Like all KTM 4-stroke motorcycles, the 250 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 all our factory riders had their say in shaping the plastics. Their goal: complete harmony between rider and bike. And so it turned out. Perfect ergonomics and contact points, maximum freedom of movement, a low seat height and sweet comfort, especially in the rear part of the seat. The I-beam structures of the front and rear fenders are prime examples of such an intelligent design, guaranteeing maximum stability and a low weight thanks to well thought-out construction and mounting. Plus: they stay cleaner for longer.
- Graphics: A new, tailor-made kit, fit for a king. Because in this sport, champs deserve to look the part regardless of the dirt.
- Design: 1-cylinder, 4-stroke engine
- Displacement: 249.9 cm³
- Bore: 78 mm
- Stroke: 52.3 mm
- Starter: Electric starter
- Transmission: 5-speed
- Primary drive: 24:73
- Secondary gear ratio: 14:51
- Clutch: Wet, CSS 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): 310 mm
- Suspension travel (rear): 300 mm
- 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"
- Steering head angle: 63.9 °
- Wheelbase: 1485 ± 10 mm
- Ground clearance: 370 mm
- Seat height: 960 mm
- Tank capacity (approx.): 7 l
- Weight READY TO RACE (without fuel): 98.2 kg
- Engine Type
- 1-cylinder, 4-stroke engine
- 249.9 cm³
- Bore and Stroke
- 78 x 52.3 mm
- Front Suspension
- WP-USD, AER 48, Ø 48 mm
- Front Brakes
- Disc brake
- Rear Suspension
- WP shock absorber with linkage
- Rear Brakes
- Disc brake
- Dry Weight
- 98.2 kg
- Fuel Capacity
- 7 L
- 1485 ± 10 mm
- Ground Clearance
- 370 mm
- Seat Height
- 960 mm
- Final Drive
- Chain: 5/8 x 1/4 in.