Big Bore Cylinder Kit Ø85mm | 300cc

Unlock the Full Potential of Your KTM SX-F 250 (2019–2022)

Take your KTM SX-F 250 to the next level with the Athena Extreme Big Bore Kit, increasing displacement to 300 cc and delivering significant gains in power, torque, and throttle response across the entire RPM range. Designed for riders who demand maximum performance without compromising the lightweight agility KTM is known for.

Performance Upgrade for KTM SX-F 250

The kit includes an aluminum cylinder with an 85 mm steel liner, a high-performance forged piston, wrist pin, circlips, and a complete gasket set for seamless installation. Developed through years of off-road and racing R&D, this kit ensures a broad, smooth power delivery suitable for both motocross and enduro.

Advanced Electronics with GET Boost

The kit also features the GET Boost electronic module from Athena’s GET division, optimizing engine performance without needing to reflash the OEM ECU. With a pre-installed map tailored to this 300 cc setup, GET Boost unleashes your engine’s full potential safely and reliably. GET is trusted by top MXGP and AMA Supercross teams worldwide.

Plug & Play Integration

Installation is straightforward: simply disconnect the injector and throttle body connectors and plug in the GET harness. No ECU modifications or reprogramming required. The system integrates seamlessly with KTM SX-F 250 models from 2016 to 2022, delivering immediate performance gains.

Cylinder Specifications

The cylinder is made from a high-silicon aluminum alloy and features a co-fused steel liner, a proprietary Athena process that enhances heat dissipation and reduces premature wear. The internal geometry is engineered for optimal combustion sealing and to prevent fluid or gas leakage under high stress.

Forged High-Performance Piston

The forged aluminum piston is CNC-machined to tight tolerances and coated with molybdenum disulfide to reduce friction and noise. The aerospace-grade steel wrist pin is DLC-coated for exceptional hardness, low friction, and maximum durability—even in extreme racing conditions.

Racing-Grade Gasket Kit

The included high-quality gasket set is engineered for perfect sealing with the oversized cylinder. The head gasket is MLS (Multi-Layer Steel), laser-cut from stainless steel for long-lasting performance under high pressure and thermal loads.

Take Your KTM SX-F 250 to the Next Level

The Athena Extreme 300 cc Big Bore Kit with GET Boost is the ultimate performance upgrade for serious riders. More power, enhanced durability, and a track-ready experience that will keep you pushing harder every lap.