{"product_id":"namura-nx-40025-bka-top-end-kit-66-36-mm-ceramic-composite-piston-for-yamaha-yz250-and-yz250x","title":"Namura NX-40025-BKA Top End Kit 66.36 mm Ceramic-Composite Piston for Yamaha YZ250 and YZ250X","description":"\u003cp\u003eRestore top-end performance with the Namura NX-40025-BKA Top End Kit, designed for select Yamaha two-stroke motocross and cross-country motorcycles. This complete kit includes a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit, providing the primary components needed for a dependable top-end rebuild. The ceramic-composite piston is designed for a 66.36 mm bore application with an 11:1 compression ratio and is suitable for compatible Yamaha YZ250 and YZ250X models.\u003c\/p\u003e\u003cp\u003eNamura uses a hypereutectic casting process to increase silicon content, helping reduce expansion rates and improve wear resistance under elevated cylinder temperatures. The piston skirt features a rolled-on MOS2 coating made with Teflon and molybdenum. This bonding process is engineered to provide a stronger coating than conventional spray-on applications while reducing friction, improving heat transfer, and helping minimize the risk of cold seizures during operation.\u003c\/p\u003e\u003cp\u003eThe machined smooth piston head helps reflect combustion heat and reduce carbon buildup, supporting piston protection and consistent performance. An anodized dome further improves heat resistance and durability, while the included gaskets and top-end hardware help simplify installation. This Namura top-end kit fits 2016 and 2017 Yamaha YZ250X models, as well as Yamaha YZ250 models from 2002 through 2009. Confirm year, model, bore specification, and cylinder compatibility before installation.\u003c\/p\u003e\u003cp\u003e\u003cb\u003eFeatures:\u003c\/b\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eComplete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit\u003c\/li\u003e\n\u003cli\u003e66.36 mm piston size with an 11:1 compression ratio for compatible Yamaha applications\u003c\/li\u003e\n\u003cli\u003eMOS2 Teflon and molybdenum-coated skirt helps reduce friction, improve heat transfer, and minimize cold-seizure risk\u003c\/li\u003e\n\u003cli\u003eMachined smooth head helps reflect combustion heat and reduce carbon buildup\u003c\/li\u003e\n\u003cli\u003eAnodized dome improves heat resistance and piston durability\u003c\/li\u003e\n\u003cli\u003eHypereutectic casting process increases silicon content for reduced expansion and improved wear resistance\u003c\/li\u003e\n\u003cli\u003eFits 2016-2017 Yamaha YZ250X and 2002-2009 Yamaha YZ250 models\u003c\/li\u003e\n\u003cli\u003eBrand: Namura\u003c\/li\u003e\n\u003cli\u003eManufacturer part number: NX-40025-BKA\u003c\/li\u003e\n\u003cli\u003eVendor part number: 185-4025BA\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\nFitment:\u003cbr\u003e\n2002 Yamaha YZ250\u003cbr\u003e\n2003 Yamaha YZ250\u003cbr\u003e\n2004 Yamaha YZ250\u003cbr\u003e\n2005 Yamaha YZ250\u003cbr\u003e\n2006 Yamaha YZ250\u003cbr\u003e\n2007 Yamaha YZ250\u003cbr\u003e\n2008 Yamaha YZ250\u003cbr\u003e\n2009 Yamaha YZ250\u003cbr\u003e\n2010 Yamaha YZ250\u003cbr\u003e\n2011 Yamaha YZ250\u003cbr\u003e\n2012 Yamaha YZ250\u003cbr\u003e\n2013 Yamaha YZ250\u003cbr\u003e\n2014 Yamaha YZ250\u003cbr\u003e\n2015 Yamaha YZ250\u003cbr\u003e\n2016 Yamaha YZ250\u003cbr\u003e\n2016 Yamaha YZ250X\u003cbr\u003e\n2017 Yamaha YZ250\u003cbr\u003e\n2017 Yamaha YZ250X\u003cbr\u003e\n2018 Yamaha YZ250\u003cbr\u003e\n2018 Yamaha YZ250X\u003cbr\u003e\n2019 Yamaha YZ250\u003cbr\u003e\n2019 Yamaha YZ250X\u003cbr\u003e\n2020 Yamaha YZ250\u003cbr\u003e\n2020 Yamaha YZ250X\u003cbr\u003e\n2021 Yamaha YZ250\u003cbr\u003e\n2021 Yamaha YZ250X\u003cbr\u003e\n2022 Yamaha YZ250\u003cbr\u003e\n2022 Yamaha YZ250X","brand":"NAMURA","offers":[{"title":"Default Title","offer_id":67559799161067,"sku":"185-4025BA","price":120.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/dd77-572a583cd9540_b649e774-2b4b-4d49-b728-fb83c964257d.jpg?v=1790773036","url":"https:\/\/ctracingservices.com\/products\/namura-nx-40025-bka-top-end-kit-66-36-mm-ceramic-composite-piston-for-yamaha-yz250-and-yz250x","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}