Refresh the top end of your two-stroke engine with the Namura NX-40085K Top End Kit. Designed for Yamaha YZ85 models with a 47.44 mm standard bore and 11:1 compression ratio, this kit includes the essential components needed for a reliable rebuild, including the piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit.
The piston features MOS2, a Teflon and molybdenum coating applied using a rolled-on process to create a durable bond. This coating helps improve heat transfer, reduce friction, and minimize the risk of cold seizures. The machined smooth head is designed to reflect combustion heat and reduce carbon buildup, helping protect the piston crown while supporting consistent engine performance.
Namura also uses an anodized dome to improve heat resistance and durability. The hypereutectic casting process increases silicon content, helping reduce expansion, improve wear resistance, and withstand elevated cylinder temperatures. These features make the kit a practical choice for restoring dependable top-end performance on compatible Yamaha applications.
Fitment includes 2002–2011 Yamaha YZ85 models. Verify the model year, bore specification, and engine configuration before installation to ensure proper compatibility.
Features:
- Complete top-end kit: Includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit.
- MOS2-coated piston skirts: Helps improve heat transfer, reduce friction, and minimize cold-seizure risk.
- Machined smooth piston head: Reflects combustion heat and helps reduce carbon buildup.
- Anodized piston dome: Improves heat resistance and durability for demanding engine operation.
- Hypereutectic casting: Provides reduced expansion, increased wear resistance, and improved performance at higher cylinder temperatures.
- Fitment: Fits 2002–2011 Yamaha YZ85 models.
- Size and compression: 47.44 mm standard bore with an 11:1 compression ratio.
- Brand and part number: Namura NX-40085K.
Fitment:
2002 Yamaha YZ85
2003 Yamaha YZ85
2004 Yamaha YZ85
2005 Yamaha YZ85
2006 Yamaha YZ85
2007 Yamaha YZ85
2008 Yamaha YZ85
2009 Yamaha YZ85
2010 Yamaha YZ85
2011 Yamaha YZ85
2012 Yamaha YZ85
2013 Yamaha YZ85
2014 Yamaha YZ85
2015 Yamaha YZ85
2016 Yamaha YZ85
2017 Yamaha YZ85
2018 Yamaha YZ85