{"product_id":"namura-na-40004-2k-top-end-kit-100-47-mm-bore-9-2-1-compression-for-yamaha-yfm660r-raptor","title":"NAMURA NA-40004-2K Top End Kit, 100.47 mm Bore, 9.2:1 Compression for Yamaha YFM660R Raptor","description":"\u003cp\u003eThe NAMURA NA-40004-2K Top End Kit is a complete replacement solution for the upper engine assembly of select Yamaha YFM660R Raptor models. Designed for a 100.47 mm bore and 9.2:1 compression ratio, this kit includes the essential components needed for a reliable top-end rebuild: piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit. The kit is engineered for a precise fit and dependable performance in compatible applications.\u003c\/p\u003e\u003cp\u003eBuilt using NAMURA performance-focused manufacturing processes, the piston features MOS2, or Teflon and molybdenum, coated skirts. This rolled-on coating process creates a stronger bond than many spray-applied alternatives while helping reduce friction, improve heat transfer, and minimize the risk of cold seizures. The machined smooth piston head reflects combustion heat and helps reduce carbon buildup, supporting piston protection and consistent engine operation.\u003c\/p\u003e\u003cp\u003eThe anodized dome improves heat resistance and durability, while the hypereutectic casting process provides increased silicon content for controlled thermal expansion and enhanced wear resistance. These features allow the piston to withstand elevated cylinder temperatures while maintaining reliable service. The NAMURA NA-40004-2K fits 2001 through 2005 Yamaha YFM660R Raptor models, making it a practical choice for restoring top-end performance during engine maintenance or rebuild work.\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 strengthen the bond, reduce friction, improve heat transfer, and help prevent cold seizures.\u003c\/li\u003e\n\u003cli\u003eMachined Smooth Head: Reflects combustion heat and helps reduce carbon buildup for improved piston protection and consistent operation.\u003c\/li\u003e\n\u003cli\u003eAnodized Dome: Increases heat resistance and piston durability under demanding operating conditions.\u003c\/li\u003e\n\u003cli\u003eHypereutectic Casting: Higher silicon content helps control expansion, improve wear resistance, and withstand higher cylinder temperatures.\u003c\/li\u003e\n\u003cli\u003eApplication Fitment: Fits 2001, 2002, 2003, 2004, and 2005 Yamaha YFM660R Raptor models.\u003c\/li\u003e\n\u003cli\u003eManufacturer Part Number: NAMURA NA-40004-2K.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\nFitment:\u003cbr\u003e\n2001 Yamaha YFM660R Raptor\u003cbr\u003e\n2002 Yamaha YFM660R Raptor\u003cbr\u003e\n2003 Yamaha YFM660R Raptor\u003cbr\u003e\n2004 Yamaha YFM660R Raptor\u003cbr\u003e\n2005 Yamaha YFM660R Raptor","brand":"NAMURA","offers":[{"title":"Default Title","offer_id":67559050674411,"sku":"186-40042","price":187.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/dd77-572a583cd9540_225c5b76-953b-4974-9776-de909df9fe14.jpg?v=1790769996","url":"https:\/\/ctracingservices.com\/products\/namura-na-40004-2k-top-end-kit-100-47-mm-bore-9-2-1-compression-for-yamaha-yfm660r-raptor","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}