2017 KTM 125 SX
The whip cracking KTM 125 SX has been at the front for years. With the phenomenal performance on tap, it will be there for many more seasons to come. A compact chassis and the lowest weight out there is teamed up with a high performance 125cc 2-stroke engine for a surefire trophy collection. Get shredding, youngsters.
- Engine: The latest 125 SX engine is the most powerful and most competitive engine in its class; a clear statement that KTM is keen on keeping 2-stroke technology at the forefront of development. The secret to their success is an outstanding power-to-weight ratio, low costs and simplicity. This 125cm3 ripper has been developed with the latest KTM engineering know-how and the most advanced technology available. The results: class-leading power across the rev range, while being extremely compact and ultra-light at a mere 17.2kg. Our work here is done, scorching lap times are yours for the taking.
- Cylinder: This compact cylinder with a 54mm 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.
- Engine Cases: 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. In addition, the engine body is extremely compact, while still able to house an optional electric starter.
- Crankshaft: This reliable piece of engineering has been skillfully balanced to guarantee minimal vibration. In its latest form, it allows an increase of the displacement to 144cm3 just by replacing cylinder, piston and head. There’s no more need to change the crankshaft. Two-in-one in no time.
- Transmission: A robust 6-speed transmission was designed specifically for the small 2-stroke engine, its gear ratios perfectly in sync with the 125’s power band. The latest production technologies allowed for compact dimensions and minimal weight. Keeping safety in mind, an advanced ´No Dirt´ gear lever design prevents muck from blocking the joint. Because even dirt lovers hate mud when it’s in the wrong places.
- Carburetor: As of model year 2017, all KTM 2-stroke models are fitted with new MIKUNI TMX carburetors, replacing the Keihin products. This 38mm flat slide carb lives to provide smooth and controllable power all the way up to the limiter. And it’s less sensitive to different altitudes and temperatures, so you can pin it wherever, whenever.
- Exhaust: The engineers meticulously tuned the expansion chamber for maximum torque and power, so this little screamer is as tough as it is strong.
- 87.2 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 models are the slimmest, lightest bikes in the competition.
- 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 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 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.
- 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: 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.
- 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.
- 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. Which is also pretty cool.
- 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.
- 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, 2-stroke engine
- Displacement: 124.8 cm³
- Bore: 54 mm
- Stroke: 54.5 mm
- Starter: Kickstarter
- Transmission: 6-speed
- Primary drive: 23:73
- Secondary gear ratio: 13:50
- 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): 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: 375 mm
- Seat height: 960 mm
- Tank capacity (approx.): 7 l
- Weight READY TO RACE (without fuel): 87.2 kg
- Engine Type
- 1-cylinder, 2-stroke engine
- 124.8 cm³
- Bore and Stroke
- 54 x 54.5 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
- 87.2 kg
- Fuel Capacity
- 7 L
- 1485 ± 10 mm
- Ground Clearance
- 375 mm
- Seat Height
- 960 mm
- Final Drive
- Chain: 5/8 x 1/4 in.