{"product_id":"athena-p400485100073-304cc-big-bore-cylinder-kit-85mm-bore-forged-piston-performance-upgrade-converts-250cc-to-304cc-compatible-with-yamaha-yz250f-wr250f-2019-2023","title":"Athena P400485100073 304cc Big Bore Cylinder Kit (85mm Bore) - Forged Piston Performance Upgrade, Converts 250cc to 304cc, Compatible with Yamaha YZ250F \u0026 WR250F 2019-2023","description":"\u003cp\u003eUPGRADE YOUR DIRT BIKE TO THE NEXT LEVEL OF PERFORMANCE Extract massive power, aggressive low-end torque, and unmatched acceleration from your 250cc four-stroke engine with the Athena Big Bore Cylinder Kit (Part No. P400485100073), a premium race-proven package engineered in Italy to seamlessly convert your factory setup into a high-revving, high-output 304cc powerhouse. Entirely cast from high-grade aluminum and treated with a specialized Motor-Nicksil (Nickel-Silicon) coating, this cylinder guarantees exceptional thermal dissipation, minimal friction, and optimal wear resistance to deliver a substantial increase along the entire power curve while maintaining strict original-equipment reliability. This complete bolt-on kit comes loaded with everything required for a flawless installation—including a widened water-jacket aluminum cylinder, a high-performance forged piston coated with molybdenum, premium rings, wrist pin, clips, and a specific high-tightness multi-layer gasket set—allowing you to dramatically increase track performance without requiring any machining or structural engine modifications to your factory crankcase.\u003cbr\u003e\u003c\/p\u003e","brand":"Athena","offers":[{"title":"Default Title","offer_id":52666148913439,"sku":"P400485100073","price":1102.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0813\/2195\/1519\/files\/P400485100073-1.jpg?v=1783606459","url":"https:\/\/massdepot.com\/products\/athena-p400485100073-304cc-big-bore-cylinder-kit-85mm-bore-forged-piston-performance-upgrade-converts-250cc-to-304cc-compatible-with-yamaha-yz250f-wr250f-2019-2023","provider":"Mass Depot","version":"1.0","type":"link"}