PISTON KIT 81MM YAMAHA WR/YZ 250 14-18, ATHENA S4F08100005B 276CC BIG BORE
Forged Racing Piston Ø 80.96 mm for Athena Big Bore Cylinder. Made from a special high-performance aluminum alloy with high silicon content. Features include cutting-edge CNC machining for precise tolerances, a smooth profile for regular flow and perfect flame propagation, and molybdenum disulfide coating on some skirts to reduce friction. Piston rings, produced in Japan with wear-resistant coatings, ensure less friction and higher performance. This kit contains the piston, pin, circlips, and piston rings. Technical features: Bore Diameter 80.96 mm, Compression Ratio 13.2:1, Displacement 250 cc, Number Of Segments 3, Piston Pin Type Standard, Piston Type Forged. Manufacturer part number S4F08100005B. Partner cross reference codes: S4F08100005A, S41316296.
- SKU
- 56-K170.81.PIB
- Brand
- Athena
- Availability
- In Stock (1)
FULL DESCRIPTION
Athena 276cc Big Bore Forged Piston Kit 81mm
Enhance your motorcycle's performance with this high-quality forged piston kit from Athena. Engineered for demanding off-road applications, this kit is designed to provide superior reliability, durability, and power.
Athena pistons are manufactured using advanced CNC machining tools, ensuring exceptional dimensional accuracy. Constructed from a specialized high-performance aluminum alloy with a high silicon content, these pistons offer robustness comparable to original equipment (OE) while delivering increased strength and improved performance.
Key Features:
- Forged Piston Construction: Offers greater strength and durability compared to cast pistons.
- High-Performance Aluminum Alloy: Features high silicon content for excellent thermal resistance and strength.
- Precision Machining: CNC machined to tolerances of less than 0.01 mm for a perfect fit and optimal performance.
- Optimized Profile: Ensures smooth airflow and efficient flame propagation for better combustion.
- Molybdenum Disulfide Coating: Some piston skirts are treated to reduce friction, further boosting performance and longevity.
- High-Quality Piston Rings: Made in Japan with wear-resistant coatings (PVD or chromium nitride) for increased durability and reduced friction. Rings adapt well to the cylinder liner even at low tangential loads.
- Complete Kit: Includes piston, pin, circlips, and piston rings. All components are replaceable and interchangeable.
- Engineered and Tested in Italy: Developed by Athena's R&D department and rigorously tested on dynamometer benches and on track for validation under extreme conditions.
Technical Specifications:
- Bore Diameter: 80.96 mm
- Displacement: 276 cc (Big Bore application)
- Compression Ratio: 13.2:1
- Piston Type: Forged
- Number Of Segments: 3
- Big End Pin Diameter: 16x10x42 mm
- Piston Pin Type: Standard
- Net Weight: 0.24 Kg
Note: Products designed for increased displacement and power beyond road legal limits are intended exclusively for competitive use. Athena is not responsible for any use contrary to national regulations.


