{"product_id":"namura-na-40010-6k-top-end-kit-101-47-mm-11-1-compression-for-yamaha-grizzly-660-and-rhino-660","title":"NAMURA NA-40010-6K Top End Kit 101.47 mm, 11:1 Compression for Yamaha Grizzly 660 and Rhino 660","description":"\u003cp\u003eThe NAMURA NA-40010-6K Top End Kit is designed for select Yamaha 660cc ATV and side-by-side applications. This 101.47 mm, approximately 4-inch, oversized kit features an 11:1 compression ratio and includes the essential components needed to refresh the upper end of the engine. The kit contains a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit for a comprehensive installation.\u003c\/p\u003e\u003cp\u003eEngineered for dependable performance, the piston uses a hypereutectic casting process with increased silicon content. This construction helps reduce expansion, improve wear resistance, and withstand elevated cylinder temperatures. The piston skirt features NAMURA’s MOS2, or Teflon\/molybdenum, coating. Its rolled-on application creates a strong bond that helps reduce friction, improve heat transfer, and minimize the risk of cold seizures.\u003c\/p\u003e\u003cp\u003eThe machined smooth piston head helps reflect combustion heat and reduce carbon buildup, supporting durability and consistent operation. An anodized dome improves heat resistance and strength compared with non-anodized designs. Together, these features help protect the piston under demanding riding conditions while supporting reliable engine performance.\u003c\/p\u003e\u003cp\u003eThe NAMURA NA-40010-6K fits 2002–2008 Yamaha YFM660FG Grizzly 4WD IRS models and 2004–2006 Yamaha YXR660F Rhino 660 models. Verify the vehicle year, model, bore requirement, and compression specifications before installation. This is a top-end replacement kit intended for compatible Yamaha 660 engines.\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\u003e101.47 mm Bore: Provides an approximately 4-inch piston diameter with a 1.50 mm oversize specification.\u003c\/li\u003e\n\u003cli\u003e11:1 Compression Ratio: Designed for compatible Yamaha 660 engine applications.\u003c\/li\u003e\n\u003cli\u003eMOS2-Coated Skirt: Rolled-on Teflon and molybdenum coating 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 on the piston crown.\u003c\/li\u003e\n\u003cli\u003eAnodized Dome: Improves heat resistance and durability for demanding operating conditions.\u003c\/li\u003e\n\u003cli\u003eHypereutectic Construction: Increased silicon content helps reduce expansion, improve wear resistance, and withstand higher cylinder temperatures.\u003c\/li\u003e\n\u003cli\u003eFitment: Compatible with 2002–2008 Yamaha YFM660FG Grizzly 4WD IRS models and 2004–2006 Yamaha YXR660F Rhino 660 models.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cbr\u003e\nFitment:\u003cbr\u003e\n2002 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2003 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2004 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2004 Yamaha YXR660F Rhino 660\u003cbr\u003e\n2005 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2005 Yamaha YXR660F Rhino 660\u003cbr\u003e\n2006 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2006 Yamaha YXR660F Rhino 660\u003cbr\u003e\n2007 Yamaha YFM660FG Grizzly 4WD [IRS]\u003cbr\u003e\n2007 Yamaha YXR660F Rhino 660\u003cbr\u003e\n2008 Yamaha YFM660FG Grizzly 4WD [IRS]","brand":"NAMURA","offers":[{"title":"Default Title","offer_id":67559032455403,"sku":"186-40106","price":198.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0611\/3882\/9547\/files\/dd77-572a583cd9540_797332f3-d2c9-4cae-a287-8bc2fd586a3c.jpg?v=1790769638","url":"https:\/\/ctracingservices.com\/products\/namura-na-40010-6k-top-end-kit-101-47-mm-11-1-compression-for-yamaha-grizzly-660-and-rhino-660","provider":"Cascade Tire \u0026 Racing Services","version":"1.0","type":"link"}