{"product_id":"83mm-290cc-big-bore-cylinder-kit-yz250f-01-07-wr250f-01-12-athena","title":"Yamaha YZ250F 01–07 \u0026 WR250F 01–12 83mm 290cc Big Bore Kit – Athena (2001-2012)","description":"\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003eTransform your YZ250F\/WR250F into a 290cc torque monster. Bolt-on install, no machining—just explosive mid-range power and race-proven durability.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003eThe Athena P400485100012 is a complete 83mm big bore race kit that takes 2001–2007 Yamaha YZ250F and 2001–2012 Yamaha WR250F from 249cc to 290cc (+41cc). Nickel-carbide cylinder, Factory Works porting, 12.5:1 forged piston, hard-anodized power valves. Cylinder head not included.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003e\u003cstrong\u003eWhat's Included\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc space-y-2.5 pl-7\"\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003e83mm Nickel-Carbide Cylinder – Factory Works porting\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eForged Piston Kit – 12.5:1 compression, molybdenum coating, rings, pin, clips\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eHard-Anodized Power Valves – high-flow, non-OEM\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eAthena Top-End Gasket Set – head\/base gaskets, seals, hardware\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003e\u003cstrong\u003eKey Features\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc space-y-2.5 pl-7\"\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003e83mm big bore — +41cc (249cc → 290cc)\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eNickel-carbide plating — extreme durability, low friction\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eLarger water jackets — superior cooling under race load\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eFactory Works porting — max airflow, pro-tuned performance\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003e12.5:1 forged piston — explosive mid-top power\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eHard-anodized power valves — faster response, longer life\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eMade in Italy — race-proven precision\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003e\u003cstrong\u003eFitment\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc space-y-2.5 pl-7\"\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003e2001–2007 Yamaha YZ250F\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003e2001–2012 Yamaha WR250F\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body whitespace-normal break-words\"\u003e\u003cstrong\u003eInstall Notes\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc space-y-2.5 pl-7\"\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eReuses OEM cylinder head (not included)\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eAdvanced install — engine disassembly required\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words\"\u003eJetting\/tuning recommended for optimal performance\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Parts Unlimited","offers":[{"title":"Default Title","offer_id":47511583228129,"sku":"0931-0024","price":1142.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1219\/2993\/files\/yamaha-yz250f-0107-wr250f-0112-83mm-290cc-big-bore-kit-athena-5209134.png?v=1764104945","url":"https:\/\/dunegoonshop.com\/products\/83mm-290cc-big-bore-cylinder-kit-yz250f-01-07-wr250f-01-12-athena","provider":"Dune Goons","version":"1.0","type":"link"}