KTM SX 85 - HISTORY

After nearly ten years away from this displacement class, KTM made an impressive comeback in 2004 by introducing a highly refined 85 cc racing bike aimed at young competitors. From the very beginning, the SX 85 quickly became the benchmark in its category. With the PDS rear suspension taken from KTM’s larger models, a modern and powerful 2-stroke engine with exhaust valve system, and a massive 43 mm front fork, the competition had little to counter the Austrian “orange rocket.”

The successful chassis remained largely unchanged until 2012, receiving only minor updates, before being completely redesigned and modernized in 2013. Another major update followed in 2018: the SX 85 was fitted with an air fork that can be easily adjusted to the rider’s weight, along with a completely new engine featuring a modern architecture. In 2025, the chassis was once again significantly revised, while the proven engine platform remained unchanged. Performance, already at a very high level, was further improved, allowing the KTM 85 SX to remain the queen of its class despite strong competition.

This compact race bike is available in small-wheel and big-wheel versions and is designed for riders with a height of approximately 1.35 m to 1.65 m. Its strong performance makes it the go-to choice for young racers aiming for consistent results.

The KTM 85 SX is not road-legal and is intended exclusively for leisure and competitive use on racetracks and motocross circuits.

KTM 85 SX - TECHNICAL DATA

ENGINE DATA:

• Type: 2-stroke single cylinder
• Lubrication: premix
• Mechanical exhaust valve system
• Liquid-cooled
• Displacement: 84.93 cc
• Bore x stroke: 47 x 48.95 mm
• Compression ratio: n.c.
• Carburetor: Keihin PWK 28
• Electronic ignition
• Starter: Kickstarter
• Transmission: 6-speed gearbox
• Clutch: hydraulic multi-plate clutch in oil bath
• Transmission oil: 15W50 (4-stroke engine oil)
• Standard spark plug: Brisk AR10C

CHASSIS:

• Chassis type: Steel frame with central tube and double cradle
• Seat height: small wheel = 845 mm / large wheel = 871 mm
• Specified dry weight: small wheel = 68 kg / large wheel = 69 kg
• Fuel tank: 5.4 l
• Front tire: 70/100-19 (large wheel) / 70/100-17 (small wheel)
• Rear tire: 90/100-16 (large wheel) / 90/100-14 (small wheel)
• Front brake: 240mm brake disk
• Rear brake: 210mm brake disk
• Final drive (stock): small wheel = 13/46 ; large wheel = 13/49

SUSPENSION:

• Fork: 43 mm upside-down WP XACT (air)
• Fork travel: 278 mm
• Rear shock absorber: WP XACT (PDS system)
• Rear suspension travel: 289 mm

KTM SX 85 IN OUR STORE:

In our online store you will find a large selection of spare and tuning parts for the KTM SX 85.

For riders who care about looks, we offer numerous plastic parts and fairings.

For regular maintenance and repairs, we have engine oil, gear oil, spark plugs, levers and brake pads.

For larger projects, we have pistons, crankshafts, gearbox bearings and clutches for the engine, as well as fork seals, connecting rod bearings and other chassis parts.

For ambitious racing drivers, we also offer exhausts, reed valves, oversize brakes, holeshot kits and other high-performance components.