It took extreme 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, ensuring that the only rider surprised by the incredible performance is the competition.

The cylinder on the 2021 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 and power delivery. This translates into 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.

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. The gearbox features a new drive shaft which uses a screw for front sprocket fixation and diaphragm spring instead of a circlip, ensuring optimal front sprocket fixation. 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 85 SX features a strong and reliable clutch with an extremely compact design. The clutch is easily actuated by the Formula hydraulic system, which conveniently ensures that play is always compensated for, keeping the clutch bite 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 rideability.

The KTM 85 SX is fitted with a KEIHIN PWK carburetor. This 28 mm flat slide carb lives to provide smooth and controllable power all the way up to the rev limitation.

Maintaining the optimal engine temperature is crucial to ensuring consistent horsepower throughout the ride. The KTM 85 SX features radiators which are positioned for a lower center of gravity. Their design matches the shrouds perfectly and offers a great slim feel to the 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 serve not only 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 rideability. The header pipe is produced 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 has been reworked with improved packing wool (40 g lighter), guarenteeing that sweet 2-stroke sound and falling safely within the FIM noise limits.

The frame on the KTM 85 SX is a scaled-down version of the championship-proven full-size frames. It is professionally crafted using hydroformed 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 frames feature highly durable orange powder coating and come with standard frame protectors.

The one-piece swingarm is manufactured using a gravity die-cast production process for exceptional strength at the lowest possible weight. It offers a wide range of adjustment for the rear wheel, allowing for a shorter wheelbase on tighter, twisty tracks, or a longer wheelbase for greater stability on longer, more choppy tracks. The swingarm's chain measurement markings are visible from above, making adjustment simpler and more accurate.

Made from lightweight aluminum, the subframe provides rear fender stability and strong support for the rider at little extra weight.

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 XACT AER fork 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 reduction of 1.0 kg in weight over conventional spring forks. Importantly, the preload adjustment is extremely simple and can be adjusted 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 XACT rear shock absorber with the sophisticated PDS (Progressive Damping System). The design offers a high progression rate and an excellent response. It allows an impressive 305 mm of rear wheel travel and is fully adjustable for preload, compression and rebound.

The KTM 85 SX features a newly developed Formula brake system with floating calipers - two pistons in front, one in the rear - with lightweight Wave brake discs - front 240 mm diameter, rear 220 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 easily 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 B.V. filter and filter cage design features a simple fail-proof mounting system, making filter maintenance a quick, easy and accurate task.

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 that do not require glue or wire for mounting.

The KTM 85 SX has 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.

The bodywork is fittingly finished off with aggressive, modern graphics, leaving the competition in no doubt of a rider's race-winning intentions.