85 SX 19/16
STEP INTO THE BIG LEAGUES
With the pro ranks within reach, the KTM 85 SX offers a real taste of the big league of motocross. Following in the footsteps of champions, every inch of this motorcycle mimics the proven design of the big bike range. A lightweight, WP-engineered frame houses its compact "rocket ship" of an engine, which delivers unrivalled performance and rideability. This mini warrior is the ultimate race weapon and is ready to go out and conquer all in the fight for the top step of the podium.
ENGINE & EXHAUST
It took the highest levels of ingenuity to fit the race-winning formula of KTM's bigger 2-strokes into a compact 85 cc engine. A special manufacturing process is used and provides impressive weight savings without sacrificing strength or durability. The super compact power plant is fitted with a 6-speed gear box and delivers class-leading power and rideability throughout the entire rev range. The power valve plays a key role in tailoring power delivery to suit track conditions and rider ability, making sure the only rider surprised by the incredible performance is the competition..
The cylinder on the 2019 model has a bore and stroke of 47/48.95 mm. It features a sophisticated power valve system, which controls both the exhaust valve and the sub exhaust ports, giving the bike excellent torque, power and power delivery. This translates to significant midrange performance, reducing the need to overwork the clutch in loamy or sandy conditions. An adjuster screw allows the opening time of the power valve to be adjusted to suit rider preference and track conditions. Further refinement can be made by changing between different power valve springs (available in the KTM PowerParts catalogue), which adjusts the rate at which the power valve opens, making the power hit harder or smoother, depending on preference.
CRANKCASES AND ENGINE COVERS
The crankcases are manufactured using a high pressure die-cast production process, keeping wall thickness to a minimum while retaining strength and durability. The design of the cases is very compact and aims at positioning the shaft arrangements as close as possible to the center of gravity, contributing to better handling.
The 85 SX features a light and robust 6-speed gearbox. The gear ratios have been developed to perfectly match the characteristics of the engine, while easy and precise shifting allows the rider to select the next gear quickly and confidently. Another highlight of the 85 SX transmission is the no dirt gear shifter. Similar to the footpeg design, it prevents the build-up of dirt and ensures the next gear is always available, no matter what the conditions.
The KTM 125 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.
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.
The KTM 85 SX features a strong and reliable clutch. It allows for an extremely compact design and also contributes to an outstanding durability. The clutch is easily actuated by the Formula hydraulic system, which also ensures play is always compensated for, keeping the clutch point the same throughout the ride and under all conditions.
The KTM 85 SX features a lightweight crankshaft with optimized balancing for reduced vibration and oscillating mass. As light as the crankshaft is, the rotational inertia has not been compromised, ensuring maximum torque and revs, as well as easy ride-ability.
Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 85 SX features newly designed radiators which are mounted 12 mm lower than the predecessors. This lowers the center of gravity and matches the design of the new shrouds perfectly, in order to achieve perfect ergonomics. By using CFD technology (computational fluid dynamics) together with a clever coolant circuit routing, the innovative system ensures the optimum engine temperature for the highest performance, no matter what the conditions. The radiators also feature special protectors that don't only serve as protection from flying rocks and debris but also as a brace that disperses energy around the radiators in the event of an impact.
The exhaust system has been designed to perfectly match the engine's power characteristics and contributes to the outstanding all-round performance and ride-ability. The header pipe is using a 3-dimensional stamping process. Once the components have been shaped, they are robot welded to ensure the highest level of quality, consistency and durability. The lightweight and compact silencer guarantees that sweet 2-stroke sound and falls safely within the FIM noise limits.
For the 85cc, KTM has successfully developed a chassis that not only handles the hard charging brutality of a 15-year-old, but also effectively accommodates a lightweight newcomer to the class. This is effectively achieved through its lightweight, high-tech steel frame. It has optimized flex characteristics that provide a great feeling for the rider and help to soak up those big hits, while also delivering excellent agility and high-speed stability. Every element is designed to work in perfect harmony and contributes to an intuitive ride like no other.
The frame on the KTM 85 SX is a scaled down version of the championship-proven full-size frames. It is professionally crafted using hydro formed Chromium Molybdenum steel tubes that are robot welded, ensuring the highest levels of consistent quality. The flex characteristics have been specifically tailored for easy handling and optimal comfort, while working in perfect harmony with the suspension, to ensure excellent agility and high-speed stability. The frame also features "no-dirt" footpegs which have a simple but effective self-cleaning system that ensures the footpegs return to their original position, providing complete control in all conditions. For 2019, the frames feature the same highly durable orange powder coating as the KTM Factory Machines and come with standard frame protectors.
Made from lightweight aluminum, the new subframe features a shorter and more compact profile. It is now 75mm shorter and 0.2kg lighter, which not only contributes to the overall weight reduction but also improves mass centralization.
Black Excel rims and CNC-machined hubs ensure the strongest base of forward momentum on the KTM 85 SX. Maxxis tires have been fitted to deliver exceptional straight-line stability and excellent traction on a wide variety of terrain, ensuring the power ends up where it is intended - on the ground.
The KTM 85 SX front fork features the same suspension technology found in the full-size motocross range. The WP AER 43 consists of a split fork design with a capsuled air spring in the left leg and the trusted oil damping system in the right leg. It offers a significant improvement in suspension performance with a massive 1.0 kg reduction in weight over conventional spring forks. Importantly, the preload adjustment is extremely simple and can be done by using the single air pressure valve and supplied air pump. The design also allows for easy access to compression and rebound clickers.
The KTM 85 SX features a WP Xplor PDS (Progressive Damping System) rear shock absorber. The design offers a high progression rate and excellent response. It provides the wheel with a total of 305 mm of travel and is fully adjustable for preload, compression and rebound.
The KTM 85 SX features the Formula brake system with radial calipers - four pistons in front, two in the rear - with lightweight Wave brake discs - front 240 mm diameter, rear 210 mm. The system is the benchmark in terms of controlled action and braking performance, ensuring powerful and confident braking.
The KTM 85 SX airbox is designed to optimize the small space available to deliver the best possible performance, while still maintaining the highest level of filter protection. The air filter is esily accessed, without tools, by removing the left side panel. Knowing that air literally breathes power into the motor, KTM has ensured that the process of inserting a new clean filter could not be any easier. The Twin Air filter and filter cage design features a simple fail-proof mounting system, making filter maintenance a quick, easy and accurate task.
ERGONOMICS & COMFORT
85cc riders come in all shapes and sizes and require intelligent motorcycle design to deal with their wide range of dynamics. For optimal high-performance ergonomics, KTM used the proven design of the big bike range on the KTM 85 SX. The goal was to provide a neutral riding position that, together with perfectly shaped bodywork, offers the best rider comfort and maneuverability. A rider's main interaction with the motorcycle comes through the seat, footpegs and handlebars, which is why KTM has used the best quality parts in these areas. The placement of these crucial contact points is also vitally important for balance and control and, through various handlebar position options, can be adjusted to suit a rider's preference. This ensures the optimal riding position for race-winning performance.
The KTM 85 SX features a strong, lightweight tapered aluminum handlebar, with a specifically shaped bend to suit the overall ergonomics. Additionally, the bike comes standard with ODI lock-on grips, which include a vulcanized grip on the right side and a lock-on grip on the left, which does not require glue or wire for mounting.
BODYWORK & GRAPHICS
The bodywork on the 2019 KTM 85 SX was designed to have the same touch points and overall feeling as the full size SX range. This similarity in bodywork is great preparation for an 85 cc rider's imminent move to the bigger bikes of pro-level motocross, making the transition as seamless as possible. KTM factory riders, KTM R&D and Kiska Design all contributed to achieving the goal of complete harmony between rider and bike. These contact points allow maximum freedom of movement and improved agility. The front and rear fenders have an I-beam structure, which are prime examples of the intelligent design that produces maximum stability with the lowest possible weight. The bodywork is fittingly finished off with aggressive, modern graphics, leaving the competition in no doubt of a rider's race-winning intentions.
The 2019 SX models feature the latest in-mold graphics, matching the factory-look orange frames and new bodywork perfectly. They have a fast and aggressive style that screams READY TO RACE, leaving no doubt as to the bikes' high-performance intentions.
SOFTWARE & ELECTRONICS
Absolute performance purity is the name of the game when it comes to electronics and the new KTM 85 SX. Undiluted 2-stroke simplicity with an hour meter to keep a check on how long you've been shredding and an optional rev counter to assist with perfect setup.
1-cylinder, 2-stroke engine
Wet, multi-disc clutch, Formula hydraulics
Central-tube frame with double-cradle
WP-USD, AER 43, Ø 43 mm
Suspension travel (front)
Suspension travel (rear)
Front brake disc diameter
Rear brake disc diameter
1/2 x 5/16"
Steering head angle
Tank capacity (approx.)
Weight READY TO RACE (without fuel)
The illustrated vehicles may vary in selected details from the production models and some illustrations feature optional equipment available at additional cost.
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