2018 KTM 250 SX
The KTM 250 SX has one of the best power-to-weight ratios in the world of dirt, forming the ultimate punch against more complex 4-stroke rivals. With the grunt to devour all sorts of tracks and terrains, and a lightweight chassis keen to skim the surface, this masterpiece of KTM’s R&D and Motorsport departments is born to lead the next pack of winners that prefer premix.
- Engine: The engine of the KTM 250 SX has been known and respected for being the most powerful 2-stroke engine in its class. 2-strokes really do have a future at KTM. Their outstanding power-to-weight ratio, low cost and simplicity see to that. The KTM 250 SX engine has been optimized for mass centralization, comes with a twin-valve controlled power valve, a balancer shaft for less engine vibrations, a 5-speed transmission and a hydraulically operated DDS clutch. This compact racer truly outshines the competition with its ripping performance and is the right choice for lovers of low purchase and maintenance costs. Oh, and of course don’t forget that 2-stroke snarl when you’re on the pipe
- Cylinder: The newly developed cylinder of the 250 SX - with a bore of 66.4mm - has all-new ports and is fitted with an overhauled power valve system. This system features a sophisticated mechanism for the lateral support exhaust ports, providing smooth and controllable power on tap. Furthermore, it’s possible to change the bike’s power delivery in seconds thanks to two supplied powervalve springs. Limitless settings for different tracks and preferences are up for grabs. Throw everything you have at it; new water jackets in the cylinder and head will take care of excess heat and reworked lateral cylinder head brackets allow a more efficient fixation of the engine to the frame via lightweight head stays. Yes, this is a serious piece of kit.
- Crankcases: These all-new die-cast engine cases feature an 4mm higher clutch shaft and a 19.5mm higher crankshaft, resulting in better mass centralization and quicker handling. In addition, it allows the implementation of a counter balance shaft. So your ride will be as relaxed as it is rapid. Plus, your new favorite engine will keep looking as fresh as the day you bought it with redesigned engine covers featuring a smart surface structure in order to reduce the wear caused by the rider’s boots.
- Transmission: A robust 5-speed transmission, its gear ratios perfectly in sync with the 250’s power band. An advanced ´No Dirt´ gear shift lever design prevents mud and sand from jamming the joint of the lever and guarantees trouble-free shifting.
- Balancer Shaft: Say goodbye to numb feet and hands. This engine design allows the implementation of a lateral balancer shaft in order to keep the vibrations to a minimum. You know what that means: more comfort, less fatigue, more racing.
- Clutch: The 250 SX 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.
- Carburetor: The KTM 250 SX is fitted with a MIKUNI TMX carburetor. This 38mm flat slide carb lives to provide smooth and controllable power all the way up to the rev limitation. With a new intake manifold the carburetor is turned 7° in order to reduce the overflow of fuel. And it’s less sensitive to different altitudes and temperatures, so you can pin it wherever, whenever.
- Ignition: Its 72mm stroke is the same, the rest is brand new. The 250 SX’s crank has been rebalanced, revamped and set-up with a counter balance shaft to kill vibrations, not your vibe.
- Exhaust System: The engineers meticulously tuned the resonator chamber for maximum torque and power, so this screamer is as tough as it is strong.
- Featherweight: KTM engineers just love dropping weight year after year. The result: the 2018 KTM SX models are the slimmest, lightest dirt bikes out there.
- 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 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 tiptoes the scales at less than 2 pounds.
- 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 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.
- 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 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: 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.
- 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.
- 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 model line.
- 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 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.
- Design: 1-cylinder, 2-stroke engine
- Displacement: 249 cm³
- Bore: 66.4 mm
- Stroke: 72 mm
- Starter: Kickstarter
- Transmission: 5-speed
- Primary drive: 26:73
- Secondary gear ratio: 14:50
- Clutch: Wet, DDS multi-disc clutch, Brembo hydraulics
- EMS: Kokusan
- Frame design: Chrome-molybdenum 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): 210.32 lb.
- Suspension travel (rear): 11.81 in.
- Tank capacity (approx.): 1.85 US gal.
- Engine Type
- 1-cylinder, 2-stroke engine
- 249 cm³
- Bore and Stroke
- 66.4 x 72 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
- 210.32 lb.
- Fuel Capacity
- 1.85 US gal.
- Seat Height
- 37.8 in.
- Final Drive
- Chain: 5/8 x 1/4 in.