85 SX 17/14 - 2020


Model Description

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.

KTM has designed the exhaust system fitted to the KTM 85 SX to match the power delivery of the engine. This contributes to the unrivaled performance and to the excellent rideability of this bike. The header is manufactured using a special 3D stamping process. The individually shaped components are welded together using robots – this guarantees maximum durability and compliance with the highest quality standards, which characterize all products manufactured by KTM. The particularly lightweight silencer complies with the sound limits specified by the FIM.

The KTM 85 SX 2-stroke engine has a bore diameter and stroke of 47 and 48.95 mm respectively. A particular highlight is the innovative power valve. This system controls both the main exhaust port and the two sub ports. The result is an unrivaled power and torque with an impressive mid-range power, in addition to excellent control. This means that on sand and muddy terrain in particular, the rider does not need to use the clutch as much. A screw adjuster allows the timing of the power valve to be fine-tuned to suit the rider's preferences or the track conditions. With the aid of various power valve springs, which are available from the KTM PowerParts program, the power valve can be adjusted even further.

The engine cases are manufactured using a high-pressure die-cast process offering the benefit of minimized wall thicknesses, combined with high strength and durability. In addition, due to this very compact design, the crankshaft has been located very close to the bike's centre of gravity – this enhances agility and predictable handling.

The robust and reliable clutch in the KTM 85 SX has a diaphragm spring. This reduces the clutch lever force and contributes to the extremely compact construction. As a result of the hydraulic clutch mechanism from Formula, the pressure point remains unchanged throughout the entire service life of the clutch, regardless of the ambient conditions.

KTM 85 SX riders enjoy the benefits of the lightweight and robust 6-speed transmission. The gear ratios, which are matched perfectly to the engine characteristics, deliver powerful acceleration whatever the situation. The gear changes are very smooth and precise, allowing the rider to concentrate on keeping to his ideal line. The design of the self-cleaning gear shift lever is similar to that of the footpegs and prevents dirt from building up to guarantee perfect control in all conditions.

With its state-of-the-art 2-stroke technology, the KTM 85 SX is setting new performance standards in the highly competitive 85cc class. KTM has mated the extremely compact engine to a precise 6-speed transmission, with the result that the KTM 85 SX is an absolute knock-out over the entire rpm range, delivering first-rate performance and exemplary rideability. The key to the engine's unrivaled performance is the specially designed power valve, which controls the exhaust valve and provides a particularly smooth and consistent power delivery.

The KTM 85 SX features unbeatable performance in all conditions. One of the key factors for this is the intelligent cooling circuit with integrated crankcase cooling and two radiators. This advanced solution provides a constant temperature balance and consistent high performance. The coolant is rooted from the cylinder head through the frame triangle directly to the aluminum radiators which have been flow-optimized using modern computational fluid dynamics (CFD) technology. The specially designed radiator shrouds not only protect the "heart" of the KTM 85 SX from dirt and flying stones, but also deflect impact energy around the radiators in the event of a crash.

The air filter box has been designed specifically to combine maximum performance with maximum protection. The air filter is easily accessible without any special tool. All that needs to be done is to remove the left-hand side cover. The Twin Air filter and case are also designed to simplify maintenance and to prevent the filter from being installed incorrectly.

The KTM 85 SX benefits from the latest in suspension technology that is also used in the brand's full-sized motocross machines. The best example of this is the WP XACT fork, which combines air suspension in the left leg and the damping function in the right leg. Compared with conventional forks, the WP XACT with its AER technology and 43 mm of diameter features a further improvement in suspension performance and also offers a significant reduction in weight of 1.0 kg. Adjusting the preload on the fork is carried out easily and quickly by means of a single air valve and the fork air pump supplied with the bike, and by twisting the easy-to-reach dials for compression and rebound.

KTM 85 SX riders benefit from the WP XACT shock absorber with the proven PDS. PDS stands for the unique progressive damping system developed by KTM in collaboration with WP. It combines a high progression rate with excellent resistance to bottoming out. It offers a generous 305 mm of rear wheel travel and can be adjusted for preload, compression and rebound.

Model Specification


Engine Type

Single cylinder, 2-stroke


84.9 cc




6 gears

Engine Lubrication

Mixture lubrication


Liquid cooled


Wet multi-disc clutch, Formula hydraulics


MEDJ Digital



Double grinded central double-cradle-type frame


1/2 x 5/16

Steering Head Angle

66 degrees

Tank Capacity

5.2 litres


Primary Gear Ratio


Secondary Gear Ratio


Brake System Front

Disc brake 240 mm

Brake System Rear

Disc brake 210 mm


Front Suspension

XACT 43 WP upside-down fork, 43 mm

Rear Suspension

XACT WP PDS shock absorber

Suspension Travel Front

278 mm

Suspension Travel Rear

305 mm



47 mm


48.95 mm


1290 mm

Ground Clearance (unloaded)

336 mm

Seat Height

865 mm

Weight (No Fuel)

67 kg


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