The Namura NX-40025-C Piston Kit is a precision replacement piston assembly designed for select Yamaha two-stroke motocross and cross-country motorcycles. This ceramic-coated piston kit features a 66.37 mm bore size, a 10.9:1 compression ratio, and a +0.02 mm oversize specification for applications requiring accurate replacement components. It is engineered to support dependable engine performance, proper cylinder fitment, and consistent operation when installed according to the motorcycle manufacturer's service procedures.
Each kit includes an individually wrapped Namura piston, a set of OEM-quality piston rings packaged separately, an OEM-quality wrist pin, and cir-clips. The components are supplied together to simplify piston replacement and help ensure the key hardware required for installation is included. Verify cylinder condition, piston-to-cylinder clearance, ring end gap, and all installation specifications before assembly.
Fitment includes 1999–2006 Yamaha YZ250 models and 2016–2017 Yamaha YZ250X models. This product is manufactured by Namura and is identified by manufacturer part number NX-40025-C and vendor part number 184-40025C. Confirm the model year, cylinder specifications, and required oversize before ordering to ensure proper compatibility.
Features:
- 66.37 mm bore size with a +0.02 mm oversize specification
- 10.9:1 compression ratio for compatible Yamaha engine applications
- Ceramic-coated piston designed for select Yamaha YZ250 and YZ250X models
- Individually wrapped Namura piston for protected handling
- OEM-quality piston rings supplied in a separate package
- OEM-quality wrist pin and cir-clips included
- Fits 1999–2006 Yamaha YZ250 and 2016–2017 Yamaha YZ250X models
- Brand: Namura
- Manufacturer part number: NX-40025-C
- Vendor part number: 184-40025C
Fitment:
1999 Yamaha YZ250
2000 Yamaha YZ250
2001 Yamaha YZ250
2002 Yamaha YZ250
2003 Yamaha YZ250
2004 Yamaha YZ250
2005 Yamaha YZ250
2006 Yamaha YZ250
2007 Yamaha YZ250
2008 Yamaha YZ250
2009 Yamaha YZ250
2010 Yamaha YZ250
2011 Yamaha YZ250
2012 Yamaha YZ250
2013 Yamaha YZ250
2014 Yamaha YZ250
2015 Yamaha YZ250
2016 Yamaha YZ250
2016 Yamaha YZ250X
2017 Yamaha YZ250
2017 Yamaha YZ250X
2018 Yamaha YZ250
2018 Yamaha YZ250X
2019 Yamaha YZ250
2019 Yamaha YZ250X
2020 Yamaha YZ250
2020 Yamaha YZ250X
2021 Yamaha YZ250
2021 Yamaha YZ250X
2022 Yamaha YZ250
2022 Yamaha YZ250X