{"product_id":"namura-top-end-kit-for-yamaha-yz250-and-yz250x-66-35-mm-standard-bore-11-1-compression","title":"Namura Top End Kit for Yamaha YZ250 and YZ250X, 66.35 mm Standard Bore, 11:1 Compression","description":"\u003cp\u003eRestore top-end performance with the Namura NX-40025KA Top End Kit, designed for select Yamaha YZ250 and YZ250X models. This kit includes a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit for a comprehensive engine rebuild solution. The 66.35 mm standard-bore piston and 11:1 compression ratio are engineered for compatible Yamaha two-stroke applications.\u003c\/p\u003e\u003cp\u003eNamura uses a hypereutectic casting process to provide increased silicon content, reduced expansion, and improved wear resistance under elevated cylinder temperatures. The piston skirt features a rolled-on MOS2 coating containing Teflon and molybdenum, helping reduce friction, improve heat transfer, and minimize the risk of cold seizures. The machined smooth head helps reflect combustion heat and reduce carbon buildup, while the anodized dome improves heat resistance and piston durability.\u003c\/p\u003e\u003cp\u003eThis Namura top-end kit fits the 2016 and 2017 Yamaha YZ250X, as well as Yamaha YZ250 models from 2002 through 2009. Confirm the motorcycle year, model, bore specification, and engine configuration before installation. Manufacturer part number: NX-40025KA. Vendor part number: 185-4025A.\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\u003eMOS2-coated piston skirts help reduce friction, improve heat transfer, and reduce the risk of cold seizures\u003c\/li\u003e\n\u003cli\u003eMachined smooth piston head helps reflect combustion heat and limit carbon buildup\u003c\/li\u003e\n\u003cli\u003eAnodized piston dome increases heat resistance and durability\u003c\/li\u003e\n\u003cli\u003eHypereutectic casting process provides reduced expansion and improved wear resistance\u003c\/li\u003e\n\u003cli\u003e66.35 mm standard-bore piston with an 11:1 compression ratio\u003c\/li\u003e\n\u003cli\u003eFits 2016-2017 Yamaha YZ250X and 2002-2009 Yamaha YZ250 models\u003c\/li\u003e\n\u003cli\u003eBrand: Namura; Manufacturer part number: NX-40025KA; Vendor part number: 185-4025A\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":67559805878507,"sku":"185-4025A","price":120.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/e756-5e961c709a670.jpg?v=1790773058","url":"https:\/\/ctracingservices.com\/products\/namura-top-end-kit-for-yamaha-yz250-and-yz250x-66-35-mm-standard-bore-11-1-compression","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}