Restore top-end performance with the NAMURA NA-50025-4K Top End Kit, designed for select Polaris Trail Blazer 330 and Trail Boss 330 ATV applications. This complete kit includes a piston, piston rings, wrist pin, retaining clips, top-end bearing, and gasket kit, providing the primary components needed for a reliable top-end rebuild. The kit features a 79.45 mm piston size with a plus 1.00 mm oversize configuration and an 11:1 compression ratio.
The NAMURA piston uses a hypereutectic casting process with increased silicon content to help control expansion, improve wear resistance, and withstand elevated cylinder temperatures. Its MOS2, or Teflon/molybdenum, coated skirts use a rolled-on application process for a strong bond and help reduce friction, improve heat transfer, and minimize the risk of cold seizures. Machined smooth heads help reflect combustion heat and reduce carbon buildup, while anodized domes improve heat resistance and piston durability.
This NAMURA manufacturer part number NA-50025-4K top-end kit fits 2008–2013 Polaris Trail Blazer 330 models and 2003–2006 Polaris Trail Boss 330 models. Verify the vehicle model, year, bore specification, and required oversize before installation. The kit is supplied by the vendor under part number 186-50254 and is intended for applications requiring a plus 1.00 mm top-end piston configuration.
Features:
- Complete top-end kit includes piston, rings, wrist pin, retaining clips, top-end bearing, and gasket kit
- 79.45 mm piston size with plus 1.00 mm oversize configuration
- 11:1 compression ratio for compatible Polaris 330 applications
- MOS2 Teflon/molybdenum-coated piston skirts help reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth piston heads help reflect combustion heat and reduce carbon buildup
- Anodized piston domes provide increased heat resistance and durability
- Hypereutectic casting process provides controlled expansion and improved wear resistance
- Fits 2008–2013 Polaris Trail Blazer 330 and 2003–2006 Polaris Trail Boss 330 models
- Brand: NAMURA
- Manufacturer part number: NA-50025-4K
- Vendor part number: 186-50254
Fitment:
2003 Polaris Magnum 330 2X4
2003 Polaris Magnum 330 4X4
2003 Polaris Trail Boss 330
2004 Polaris Atp 330
2004 Polaris Magnum 330 2X4
2004 Polaris Magnum 330 4X4
2004 Polaris Trail Boss 330
2005 Polaris Atp 330
2005 Polaris Magnum 330 2X4
2005 Polaris Magnum 330 4X4
2005 Polaris Trail Boss 330
2006 Polaris Magnum 330 4X4
2006 Polaris Trail Boss 330
2007 Polaris Trail Boss 330
2008 Polaris Trail Blazer 330
2008 Polaris Trail Boss 330
2009 Polaris Trail Blazer 330
2009 Polaris Trail Boss 330
2010 Polaris Trail Blazer 330
2010 Polaris Trail Boss 330
2011 Polaris Trail Blazer 330
2011 Polaris Trail Boss 330
2012 Polaris Trail Blazer 330
2012 Polaris Trail Boss 330
2013 Polaris Trail Blazer 330
2013 Polaris Trail Boss 330