With the agility of a 125 and enough muscle to take the fight to the 250cc 4-strokes, this bike punches well above its weight. Its snarling engine sets benchmarks in terms of power and torque, rocketing its state-of-the-art chassis miles ahead of the competition. The top step of the podium does have the unmistakable scent of 2-stroke premix exhaust.
Less Is More
- Engine: The engine of the KTM 150 SX was developed with the latest know-how and state-of-the-art technology. That’s the only way to craft class-leading power all across the rev range. This is the lightest and most compact 150cc motocrosser you’ll find. So prepare for surprisingly fast lap times and baffling rideability. As this motorcycle shares many of its key components with the class-leading KTM 125 SX, the cylinder, head and piston unit can now also be fitted on a 125cc engine base converting it to a KTM 150 SX without replacing the crankshaft. Buy one, get one free. Nearly.
- Cylinder: This compact cylinder with a 58mm bore features a cutting-edge power valve unit with a sophisticated mechanism for the lateral support exhaust ports. Matched to a twin-component cylinder head, it is KTM’s secret to all-round grunt. The layout of the water jackets in the cylinder and head guarantees efficient heat dissipation when the going gets tough.
- Crankcases: For the latest engine generation the KTM engineers designed lightweight die-cast engine cases featuring a high crankshaft position located close to the center of gravity, which results in optimal mass centralization and outstanding rideability.
- Crankshaft: This reliable piece of engineering has been skillfully balanced to guarantee minimal vibrations. In its latest form, it allows a decrease of the displacement to 125cm3 just by replacing cylinder, piston and head. There’s no longer the need to change the crankshaft if you want to change displacement. Two-in-one in no time.
- Transmission: A robust 6-speed transmission was designed specifically for the small 2-stroke engine, its gear ratios are perfectly in sync with the 150’s power band. The latest production technologies allow for compact dimensions and minimal weight. An advanced ´No Dirt´gear lever design prevents mud from clogging the folding tip for reliable shifts even in the worst conditions.
- Carburetor: The KTM 150 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.
- Exhaust System: The engineers meticulously tuned the resonator chamber for maximum torque and power, so this screamer is as tough as it is strong.
- Ignition: All 2-stroke models feature a new CDI control unit with an advanced hardware which improves the starting behavior of the engine. The ignition curves remain unchanged.
- Featherweight: 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 models are the slimmest, lightest bikes on the track.
- 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, engine head stays (the connection between cylinder head and frame) are now made of lightweight aluminum. They 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 tiptoes 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.
- 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: 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.
Looks That Matter
- 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.
Always On Top Of Things
- 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 striking 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: 143.6 cm³
- Bore: 58 mm
- Stroke: 54.5 mm
- Starter: Kickstarter
- Transmission: 6-speed
- Primary drive: 23:73
- Secondary gear ratio: 13:48
- Clutch: Wet multi-disc clutch, Brembo hydraulics
- EMS: Kokusan
- 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): 192.24 lb.
- Suspension travel (rear): 11.81 in.
- Tank capacity (approx.): 1.85 US gal.
The illustrated vehicles may vary in selected details from the production models and some illustrations feature optional equipment available at additional cost. All information concerning the scope of supply, appearance, services, dimensions and weights is non-binding and specified with the proviso that mistakes, printing, setting and typing errors may occur; such information is subject to change without notice.
LIST PRICE ON NEW, if shown, is Manufacturer's Suggested Retail Price (MSRP) and limited to stock# listed. Sale Price includes all manufacturer incentives, but does not include Freight, PDI, Vehicle Processing, tire levy and taxes or any applicable finance charges.