{"product_id":"namura-nx-40000-bk-top-end-kit-for-1998-2000-yamaha-yz125-53-95-mm-bore","title":"Namura NX-40000-BK Top End Kit for 1998–2000 Yamaha YZ125, 53.95 mm Bore","description":"\u003cp\u003eUpgrade the top end of your two-stroke motorcycle with the Namura NX-40000-BK Top End Kit. Designed for select 1998, 1999, and 2000 Yamaha YZ125 models, this kit includes the essential components needed for a reliable top-end rebuild, including a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit. The kit is manufactured for a 53.95 mm bore and features an 11:1 compression ratio for compatible applications.\u003c\/p\u003e\u003cp\u003eThe piston uses Namura’s hypereutectic casting process to provide increased silicon content, reduced expansion, improved wear resistance, and dependable performance at elevated cylinder temperatures. Its MOS2, or Teflon and molybdenum, coated skirts are applied through a rolled-on process that creates a stronger bond than conventional spray-on coatings. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures during operation.\u003c\/p\u003e\u003cp\u003eAdditional piston features include machined smooth heads that reflect combustion heat and help reduce carbon buildup, supporting piston protection and consistent engine performance. The anodized dome increases heat resistance and durability, while providing greater strength than a non-anodized piston. This Namura top-end replacement kit is intended for use with the listed Yamaha YZ125 fitments and should be installed according to the motorcycle manufacturer’s service procedures. Manufacturer part number: NX-40000-BK. Vendor part number: 185-4000B.\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 Skirts: Rolled-on Teflon and molybdenum coating helps improve heat transfer, reduce friction, and minimize cold-seizure risk.\u003c\/li\u003e\n\u003cli\u003eMachined Smooth Head: Helps reflect combustion heat and reduce carbon buildup for improved piston protection.\u003c\/li\u003e\n\u003cli\u003eAnodized Dome: Improves heat resistance, durability, and piston strength.\u003c\/li\u003e\n\u003cli\u003eHypereutectic Casting: Higher silicon content helps reduce expansion, increase wear resistance, and withstand higher cylinder temperatures.\u003c\/li\u003e\n\u003cli\u003eFitment: Designed for 1998, 1999, and 2000 Yamaha YZ125 models.\u003c\/li\u003e\n\u003cli\u003eManufacturer Part Number: NX-40000-BK.\u003c\/li\u003e\n\u003cli\u003eVendor Part Number: 185-4000B.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\nFitment:\u003cbr\u003e\n1998 Yamaha YZ125\u003cbr\u003e\n1999 Yamaha YZ125\u003cbr\u003e\n2000 Yamaha YZ125","brand":"NAMURA","offers":[{"title":"Default Title","offer_id":67559911031019,"sku":"185-4000B","price":93.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/dd77-572a583cd9540_3dc4104c-6cc6-43f1-a825-add717af1a87.jpg?v=1790773236","url":"https:\/\/ctracingservices.com\/products\/namura-nx-40000-bk-top-end-kit-for-1998-2000-yamaha-yz125-53-95-mm-bore","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}