JE Piston Kit P/N: 323557 Fits: 2014 Yamaha YZ250F Forged in the USA using 2618 aluminum, yielding high tensile strength needed for high-demand performance applications Race-inspired two-ring design promotes quick revving and throttle response for noticeable power Designed specifically for each engine and use application to provide optimized performance durability Proprietary Forged Side Relief (FSR) forging design minimizes friction and power loss with reduced skirt width and saves additional weight with a shorter wrist pin Includes high-quality wrist pins, locks, and JE Pro Seal premium piston rings Made 100% in the USA Piston Series Pro Series Cylinder Head 2014 YZ250F Bore Diameter 77.00 MM Compression Ratio Actual 14.00:1 Piston Head Type Dome Piston Volume -1.18 CC Piston Material 2618 Forging Type FSR Piston Average Weight 152 GR Ring Set Included Yes Top Compression Ring Thickness 0.0320 IN Oil Ring Thickness 0.0585 IN Wrist Pin Material 9310 Nickel Carbon Steel Alloy Wrist Pin Outer Diameter 0.630 IN Wrist Pin Wall Thickness 0.140 IN