{"product_id":"namura-nx-40005-4k-top-end-kit-for-yamaha-pw-50-40-96-mm-bore-11-1-compression","title":"NAMURA NX-40005-4K Top End Kit for Yamaha PW 50, 40.96 mm Bore, 11:1 Compression","description":"\u003cp\u003eThe NAMURA NX-40005-4K Top End Kit is designed for Yamaha PW 50 models from 1990 through 1999. This complete 40.96 mm, +1.00 mm oversize kit includes a piston, piston rings, wrist pin, retaining clips, top end bearing, and gasket kit for a convenient engine rebuild solution. The 11:1 compression design supports dependable performance and is intended for applications requiring a replacement top-end assembly.\u003c\/p\u003e\u003cp\u003eThe piston features a MOS2 Teflon and molybdenum-coated skirt applied through a rolled-on process for a durable bond. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures. The machined smooth head reflects combustion heat and helps limit carbon buildup, supporting piston protection and consistent engine operation.\u003c\/p\u003e\u003cp\u003eAn anodized dome increases heat resistance and durability, while the hypereutectic casting process provides increased silicon content for controlled expansion, added wear resistance, and improved tolerance of higher cylinder temperatures. The NAMURA NX-40005-4K is manufactured for direct fitment on 1990-1999 Yamaha PW 50 models. Verify the model year, bore requirement, and engine specifications 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\u003e40.96 mm bore with +1.00 mm oversize piston specification\u003c\/li\u003e\n\u003cli\u003e11:1 compression ratio for the Yamaha PW 50 application\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 piston head helps reflect combustion heat and reduce carbon buildup\u003c\/li\u003e\n\u003cli\u003eAnodized dome increases heat resistance and piston durability\u003c\/li\u003e\n\u003cli\u003eHypereutectic casting process provides controlled expansion, improved wear resistance, and increased high-temperature capability\u003c\/li\u003e\n\u003cli\u003eFits 1990-1999 Yamaha PW 50 models\u003c\/li\u003e\n\u003cli\u003eBrand: NAMURA\u003c\/li\u003e\n\u003cli\u003eManufacturer part number: NX-40005-4K\u003c\/li\u003e\n\u003cli\u003eVendor part number: 185-40054\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\nFitment:\u003cbr\u003e\n1990 Yamaha PW 50\u003cbr\u003e\n1991 Yamaha PW 50\u003cbr\u003e\n1992 Yamaha PW 50\u003cbr\u003e\n1993 Yamaha PW 50\u003cbr\u003e\n1994 Yamaha PW 50\u003cbr\u003e\n1995 Yamaha PW 50\u003cbr\u003e\n1996 Yamaha PW 50\u003cbr\u003e\n1997 Yamaha PW 50\u003cbr\u003e\n1998 Yamaha PW 50\u003cbr\u003e\n1999 Yamaha PW 50\u003cbr\u003e\n2000 Yamaha PW 50\u003cbr\u003e\n2001 Yamaha PW 50\u003cbr\u003e\n2002 Yamaha PW 50\u003cbr\u003e\n2003 Yamaha PW 50\u003cbr\u003e\n2004 Yamaha PW 50\u003cbr\u003e\n2005 Yamaha PW 50\u003cbr\u003e\n2006 Yamaha PW 50\u003cbr\u003e\n2007 Yamaha PW 50\u003cbr\u003e\n2008 Yamaha PW 50\u003cbr\u003e\n2009 Yamaha PW 50\u003cbr\u003e\n2012 Yamaha PW 50\u003cbr\u003e\n2013 Yamaha PW 50\u003cbr\u003e\n2014 Yamaha PW 50\u003cbr\u003e\n2015 Yamaha PW 50\u003cbr\u003e\n2016 Yamaha PW 50\u003cbr\u003e\n2017 Yamaha PW 50\u003cbr\u003e\n2018 Yamaha PW 50\u003cbr\u003e\n2019 Yamaha PW 50\u003cbr\u003e\n2020 Yamaha PW 50\u003cbr\u003e\n2021 Yamaha PW 50","brand":"NAMURA","offers":[{"title":"Default Title","offer_id":67559815381227,"sku":"185-40054","price":64.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/dd77-572a583cd9540_cf62b4c6-24a7-4c68-bbd5-febe62ee9f76.jpg?v=1790773079","url":"https:\/\/ctracingservices.com\/products\/namura-nx-40005-4k-top-end-kit-for-yamaha-pw-50-40-96-mm-bore-11-1-compression","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}