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Athena Big Bore Cylinder Kit (293cc) | Yamaha YZ250 (2003–2026)
R 36,885.00
Unlock the raw power your Yamaha YZ250 was built for. The Athena P400485100042 Big Bore Kit is a complete, bolt-on performance solution that increases your displacement to 293cc without requiring permanent engine modifications.
Designed and engineered in Italy, this kit provides a significant boost in torque and horsepower across the entire power curve while maintaining the legendary reliability of your YZ250.
Key Performance Benefits
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Massive Displacement Increase: Steps up from the stock 250cc to a potent 293cc via a 72mm bore.
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Superior Cooling: Features redesigned, widened water jackets that provide a higher flow rate to keep engine temperatures stable under race conditions.
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Engineered for Durability: The light aluminum alloy cylinder is lined with Motor-Nicksil (nickel-silicon coating) for exceptional smoothness and wear resistance.
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Race-Ready Piston: Includes a forged piston with a molybdenum coating to reduce friction and extend the life of your top end.
Technical Specifications
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Feature
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Details
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Bore Diameter
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72.00 mm
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Displacement
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293.2 cc
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Compression Ratio
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15.0:1
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Wheel Power
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Approx. 45.3 HP / 7600 rpm
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Installation
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Bolt-on (No machining required)
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What’s in the Box?
This comprehensive kit includes everything needed for a seamless installation:
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High-quality Aluminum Cylinder (72mm)
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Cylinder Head & Exhaust Valve Kit
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Forged Piston, Rings, Pin, and Clips
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Athena High-Performance Gasket Set (Top End)
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Step-by-step installation instructions
Pro Tip: To achieve maximum performance gains, we recommend re-jetting your carburetor and using the specific Athena gaskets included in the kit.
Compatible with: Yamaha YZ250 (Years 2003, 2004, 2005... through 2026).