{"product_id":"wossner-8217db-piston-kit-1999-2026-yamaha-yz250-yz250x-2-stroke-size-b","title":"Wossner 8217DB Piston Kit - 1999-2026 Yamaha YZ250 YZ250X 2-Stroke Size B","description":"\u003ch3\u003eWossner 8217DB Premium Forged 2-Stroke Piston Kit - Size B\u003c\/h3\u003e\n\u003cp\u003eMaintain the legendary performance of your Yamaha 2-stroke with the Wossner 8217DB Piston Kit. Specifically engineered for 1999-2026 Yamaha YZ250 and YZ250X cylinders that require a Size B fitment, this kit is the professional choice for restoring Factory Quality power and the broad, hard-hitting powerband Yamaha is famous for. At Moto-House MX, we provide the precision-forged components required for peak reliability and optimal piston-to-wall clearance.\u003c\/p\u003e\n\u003cp\u003eForged from aerospace-grade aluminum alloy, this piston provides a massive upgrade in strength and heat resistance over cast alternatives. The permanent skirt coating is a vital feature, reducing internal friction and piston rock for a quieter engine and smoother operation. This Size B piston (66.36mm) is designed for cylinders with a 66.41mm bore, making it the ideal selection for cylinders that have seen standard use and require a slightly larger diameter to maintain perfect compression.\u003c\/p\u003e\n\u003ch3\u003eTop Features: Wossner 8217DB Piston Kit\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eStandard Size B (66.36mm):\u003c\/b\u003e Precision-engineered for 66.41mm bores to maintain perfect tolerances in used cylinders.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eAerospace Forged Alloy:\u003c\/b\u003e Premium aluminum construction for maximum durability and thermal stability.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eLow-Friction Skirt Coating:\u003c\/b\u003e Permanent coating reduces internal wear and mechanical noise for a more efficient engine.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eSingle-Ring Racing Design:\u003c\/b\u003e Optimized for reduced drag and high-RPM efficiency, ensuring maximum 250cc performance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePrecision Lightweight Machining:\u003c\/b\u003e Reduces reciprocating mass for faster revs and improved response.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eComplete Assembly:\u003c\/b\u003e Kit includes the forged piston, high-performance ring, wrist pin, and clips.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cb\u003eExpert Pro-Tip:\u003c\/b\u003e The Yamaha YZ250 engine is a masterpiece of longevity, but proper sizing is key. Size B is the standard \"go-to\" for the second or third top-end refresh on an original cylinder to compensate for natural microscopic wear of the Nikasil plating. Always ensure your power valve assembly is clean for maximum performance.\u003c\/p\u003e\n\u003ch3\u003eFitment List\u003c\/h3\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse;\" cellpadding=\"8\" border=\"1\"\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 \u0026amp; Size\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e1999-2026\u003c\/td\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYZ250\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e2016-2026\u003c\/td\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eYZ250X (Off-Road)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cb\u003eQ: What is the difference between Size A and Size B?\u003c\/b\u003e\u003cbr\u003eA: Size B (66.36mm) is exactly 0.01mm larger than Size A. This allows you to maintain the tight factory tolerances as your cylinder wall experiences very slight wear over time.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Does this kit include the wrist pin bearing?\u003c\/b\u003e\u003cbr\u003eA: No, the kit includes the piston, ring, wrist pin, and clips. We highly recommend purchasing a new small-end bearing separately whenever you refresh your top end.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Will this fit the YZ250X?\u003c\/b\u003e\u003cbr\u003eA: Yes, this piston is perfectly compatible with both the motocross-spec YZ250 and the cross-country YZ250X models from the years listed.\u003c\/p\u003e\n\u003ch3\u003eRecommended Pairings\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eTop End Gasket Kit:\u003c\/b\u003e Essential for a professional, leak-free engine rebuild.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eMotorex Cross Power 2T Oil:\u003c\/b\u003e The ultimate synthetic lubrication choice for high-performance Yamaha 2-strokes.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eRestore your Yamaha’s power and precision today. Buy now at Moto-House MX!\u003c\/p\u003e\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\u003cp\u003e \u003c\/p\u003e","brand":"WOSSNER","offers":[{"title":"Default Title","offer_id":44496004546643,"sku":"8217DB","price":182.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1754\/5421\/files\/2758051.png?v=1776230492","url":"https:\/\/motohousemx.com\/products\/wossner-8217db-piston-kit-1999-2026-yamaha-yz250-yz250x-2-stroke-size-b","provider":"Moto-House MX","version":"1.0","type":"link"}