{"product_id":"wossner-8559da-piston-kit-2001-2013-yamaha-wr250f-2001-2004-yz250f","title":"Wossner 8559DA Piston Kit - 2001-2013 Yamaha WR250F \/ 2001-2004 YZ250F","description":"\u003ch3\u003eWossner 8559DA Premium Series Forged 4-Stroke Piston Kit - Standard Size A\u003c\/h3\u003e\n\n\u003cp\u003eRevitalize your Yamaha’s high-revving 250cc engine with the Wossner 8559DA Piston Kit. Specifically engineered for the 2001-2013 Yamaha WR250F and the early generation 2001-2004 YZ250F, this Premium Series forged kit is the professional choice for restoring Factory Quality performance. At Moto-House MX, we know these five-valve Yamaha engines are legendary for their durability; Wossner’s aerospace-grade forged components ensure your machine continues to deliver reliable power on the track or the trail.\u003c\/p\u003e\n\n\u003cp\u003eForged from aerospace-grade aluminum alloy, the 8559DA maintains a 12.5:1 compression ratio, providing a perfect balance of performance and long-term reliability. This piston features advanced radial boss machining and enhanced oiling slots for superior wrist pin lubrication—an essential upgrade for the high-RPM demands of a 250cc 4-stroke. The permanent skirt coating reduces internal friction and piston rock, resulting in a quieter engine and a safer break-in period.\u003c\/p\u003e\n\n\u003ch3\u003eTop Features: Wossner 8559DA Piston Kit\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cb\u003eStandard Size A (76.96mm Piston):\u003c\/b\u003e Precision-engineered for the standard 77.00mm bore to restore original factory tolerances and compression.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003e12.5:1 Compression Ratio:\u003c\/b\u003e Delivers consistent, tractable power that matches original equipment specifications for reliable performance.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003ePremium Series Forging:\u003c\/b\u003e High-strength aluminum construction offers superior thermal resistance and structural integrity over cast pistons.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eEnhanced Lubrication Design:\u003c\/b\u003e Radial boss machining and annular grooves ensure the wrist pin stays lubricated during extended high-RPM use.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eLow-Friction Skirt Coating:\u003c\/b\u003e Permanent coating minimizes mechanical noise and protects your cylinder walls from premature wear.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eComplete Assembly:\u003c\/b\u003e Kit includes the forged piston, high-performance rings, wrist pin, and pin locks.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cb\u003eExpert Pro-Tip:\u003c\/b\u003e The Yamaha WR250F and early YZ250F utilized a unique five-valve cylinder head design. When performing a top-end refresh with the 8559DA, always inspect your valve clearances and check the cam chain for stretch. Because these engines are often used for tight woods riding or high-revving motocross, using a fresh top-end gasket kit and premium synthetic oil is vital to ensuring your new forged piston performs at its peak for seasons to come.\u003c\/p\u003e\n\n\u003ch3\u003eFitment List\u003c\/h3\u003e\n\u003ctable border=\"1\" cellpadding=\"8\" style=\"width: 100%; border-collapse: collapse;\"\u003e\n    \u003cthead\u003e\n        \u003ctr\u003e\n            \u003cth\u003eYear Range\u003c\/th\u003e\n            \u003cth\u003eVehicle Brand\u003c\/th\u003e\n            \u003cth\u003eVehicle Model\u003c\/th\u003e\n        \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n        \u003ctr\u003e\n            \u003ctd\u003e2001-2013\u003c\/td\u003e\n            \u003ctd\u003eYamaha\u003c\/td\u003e\n            \u003ctd\u003eWR250F\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n            \u003ctd\u003e2001-2004\u003c\/td\u003e\n            \u003ctd\u003eYamaha\u003c\/td\u003e\n            \u003ctd\u003eYZ250F\u003c\/td\u003e\n        \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cb\u003eQ: Is this a Standard Size piston?\u003c\/b\u003e\u003cbr\u003e\nA: Yes, this is the 76.96mm piston designed for the standard 77.00mm bore. It is the ideal choice for cylinders that are within factory service limits.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eQ: Does this kit include the gaskets?\u003c\/b\u003e\u003cbr\u003e\nA: No, the kit includes the forged piston, rings, wrist pin, and locks. A top-end gasket kit is required for a professional, leak-free rebuild and is sold separately.\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eQ: Why choose Wossner for my Yamaha?\u003c\/b\u003e\u003cbr\u003e\nA: Wossner is a leader in forged piston technology. Their pistons are denser and stronger than OEM cast parts, allowing them to better handle the heat and mechanical stress of modern 4-stroke racing.\u003c\/p\u003e\n\n\u003ch3\u003eRecommended Pairings\u003c\/h3\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cb\u003eComplete Top End Gasket Set:\u003c\/b\u003e Required for a professional seal and proper engine compression.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cb\u003eMotorex Cross Power 4T Oil:\u003c\/b\u003e Premium synthetic lubrication to protect your high-performance Yamaha engine.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eRestore your machine’s power and precision today. Buy now at Moto-House MX!\u003c\/p\u003e\n\n\u003cp\u003e\u003cb\u003eMoto-House MX – Choice of Champions\u003c\/b\u003e – is located in Clermont\/Montverde, FL. The Best Motocross\/UTV \u0026amp; ATV Shop in Central Florida. Stop by our local store in Montverde, FL or enjoy lightning-fast shipping across the USA.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n  \"@context\": \"https:\/\/schema.org\/\",\n  \"@type\": \"Product\",\n  \"name\": \"Wossner 8559DA Piston Kit\",\n  \"image\": [],\n  \"description\": \"Premium Wossner 8559DA Forged 4-Stroke Piston Kit for 2001-2013 Yamaha WR250F and 2001-2004 YZ250F. Standard Size A (76.96mm) for 77.00mm bore. 12.5:1 compression.\",\n  \"sku\": \"8559DA\",\n  \"brand\": {\n    \"@type\": \"Brand\",\n    \"name\": \"Wossner\"\n  },\n  \"offers\": {\n    \"@type\": \"Offer\",\n    \"url\": \"https:\/\/motohousemx.com\/products\/wossner-8559da-piston-kit\",\n    \"priceCurrency\": \"USD\",\n    \"availability\": \"https:\/\/schema.org\/InStock\"\n  }\n}\n\u003c\/script\u003e","brand":"WOSSNER","offers":[{"title":"Default Title","offer_id":44496002121811,"sku":"8559DA","price":184.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1754\/5421\/files\/1489002.png?v=1776230190","url":"https:\/\/motohousemx.com\/products\/wossner-8559da-piston-kit-2001-2013-yamaha-wr250f-2001-2004-yz250f","provider":"Moto-House MX","version":"1.0","type":"link"}