Cylinder Full Kit Big Bore 85mm KX250 2025-26, Athena P400250100032 300cc (Piston included)

Cylinder Full Kit Big Bore 85mm KX250 2025-26, Athena P400250100032 300cc (Piston included). Find the product specifications and compatibility information below.

Product details

• Product: Cylinder Full Kit Big Bore 85mm KX250 2025-26, Athena P400250100032 300cc (Piston included)
• Part number: 56-K315.85.KIT
• Brand: Athena
• Discover how to upgrade your Kawasaki KX 250 with Athena's Extreme Big Bore Kit, which increases displacement to 300 cc, delivering a significant boost in power and torque across the entire power band. This kit is the ideal solution for riders who want to push their bike's performance beyond standard limits while maintaining the legendary handling and lightness of this motocross machine.
• Enhance Your Kawasaki KX 250 Performance
• The kit includes an aluminium alloy cylinder with an 85 mm steel bore, a high-quality forged piston complete with pin and rings, and all necessary gaskets. This cylinder kit results from years of off-road and racing research and development, ensuring smooth and continuous power delivery suitable for all RPM ranges.
• Electronic Innovation with GET Boost
• Included in the kit is the GET Boost electronic module, developed by Athena’s GET division, which takes your Kawasaki KX 250’s performance to the next level. GET is globally recognised for its collaborations with top off-road teams, including MXGP and AMA Supercross. With GET Boost, you can fully leverage the Big Bore kit’s performance without needing to modify the original ECU or electrical system.
• Easy Installation and Maximum Integration
• Installing the GET Boost is straightforward: simply disconnect the connectors from the primary injector and throttle body, and connect them to the GET auxiliary harness. The GET Boost module, pre-calibrated specifically for this cylinder kit, connects quickly and allows you to get the most out of your engine safely and reliably.
• Cylinder Technical Specifications
• The cylinder is made from a high-silicon aluminium alloy with an integrated steel bore through Athena’s exclusive co-fusion process. This process ensures a perfect bond between the aluminium and steel, improving heat transfer and preventing premature wear. The bore geometry is designed to ensure a perfect combustion seal, preventing pressure loss and fluid or gas leaks.
• High-Performance Forged Piston
• The forged piston, crafted from aluminium alloy, combines strength and lightness. CNC machining ensures tight tolerances and precise geometries, with a molybdenum disulfide coating that reduces friction and noise. The aerospace-grade steel pin, coated with DLC, guarantees hardness and low friction for unparalleled durability and reliability.
• High-Quality Gaskets
• The included gasket set is designed to provide optimal sealing with the new cylinder. The head gasket is an MLS (Multi-layer Steel) type, made from stainless steel and laser-cut with the latest technology, ensuring perfect and long-lasting adherence under all conditions.
• Take Your Kawasaki KX 250 to the Next Level
• The Big Bore Kit for Kawasaki KX 250 with GET Boost is the ultimate choice for riders who want to maximize their bike’s performance. Increased power, superior reliability, and a riding experience that will make you enjoy every moment on the track or off-road. Get ready to never want to get off your bike again!
• Optimize your Kawasaki KX 250's performance with Athena’s Extreme Big Bore Kit and discover a new world of power and excitement.
• 85 mm bore diameter for maximum displacement increase
• No crankcase machining required for installation
• Racing forged piston with fully open boxed bridged design and anti-friction coating
• Aluminium alloy cylinder with steel cylinder liner for enhanced durability
• Bore Diameter: 85 mm
• Displacement: 296cc
• Cylinder Material: Aluminium alloy with steel liner
• Piston Type: Forged aluminium with molybdenum disulfide coating
• Vehicle Compatibility:
• Kawasaki KX 250 4T 2025-2026
• Notes:
• The cylinder head and base gaskets included are specifically developed for this kit. When disassembling the cylinder kit, replace the gaskets with the specific Athena spare gasket kit; do not use OEM replacement gaskets.
• Intended for race use only; not suitable for street use.

Compatibility

No separate vehicle-fitment table record was supplied for this part. Check any application details, sizes and specifications above before ordering.

Why buy from FDY Performance?

FDY Performance is a UK motorcycle and ATV parts specialist. We help riders find parts with clear specifications, vehicle fitment information where available and support before ordering.

Need help choosing the right part?

Contact us with your bike make, model and year, plus the part number shown above, and we can help you check compatibility.

• Call: 07765 534854
• Email: fdy@fdyperformance.com
• Website: www.fdyperformance.com