The Namura NA-50000-6K Top End Kit is a complete replacement solution for select Polaris 250 engines. This kit includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit for a convenient engine rebuild. Designed with a 73.46 mm / +1.50 mm piston size and an 11:1 compression ratio, it supports reliable performance and proper fitment for compatible Polaris applications.
The piston features MOS2, or Teflon/Molybdenum, coated skirts applied through a rolled-on process. This coating provides a strong bond while helping improve heat transfer, reduce friction, and minimize the risk of cold seizures. The machined smooth head reflects combustion heat and helps reduce carbon buildup, protecting the piston crown during operation. An anodized dome further improves heat resistance and durability, while the hypereutectic casting process adds silicon for reduced expansion, increased wear resistance, and improved performance under elevated cylinder temperatures.
Fitment includes the 1991-1992 Polaris Big Boss 250 6X6, 1989-1992 Polaris Big Boss 250 4X6, 1992-1993 and 2003-2004 Polaris Trail Blazer 250. Verify the vehicle year, model, engine configuration, and required oversize before installation. This Namura top-end kit is manufactured for dependable replacement performance and is identified by manufacturer and vendor part number NA-50000-6K.
Features:
- Complete top-end kit includes piston, rings, wrist pin, clips, top-end bearing, and gasket kit
- 73.46 mm / +1.50 mm piston size with an 11:1 compression ratio
- MOS2 Teflon/Molybdenum-coated skirt helps reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth piston head helps reflect combustion heat and reduce carbon buildup
- Anodized dome increases heat resistance and piston durability
- Hypereutectic casting process provides reduced expansion, improved wear resistance, and greater tolerance of high cylinder temperatures
- Fits 1989-1992 Polaris Big Boss 250 4X6 models
- Fits 1991-1992 Polaris Big Boss 250 6X6 models
- Fits 1992-1993 and 2003-2004 Polaris Trail Blazer 250 models
- Brand: Namura
- Manufacturer and vendor part number: NA-50000-6K
Fitment:
1989 Polaris Big Boss 250 4X6
1990 Polaris Big Boss 250 4X6
1990 Polaris Trail Blazer 250
1991 Polaris Big Boss 250 4X6
1991 Polaris Big Boss 250 6X6
1991 Polaris Trail Blazer 250
1991 Polaris Trail Boss 250 2X4
1992 Polaris Big Boss 250 4X6
1992 Polaris Big Boss 250 6X6
1992 Polaris Trail Blazer 250
1992 Polaris Trail Boss 250 2X4
1993 Polaris Trail Blazer 250
1993 Polaris Trail Boss 250 2X4
1994 Polaris Trail Blazer 250
1994 Polaris Trail Boss 250 2X4
1995 Polaris Trail Blazer 250
1995 Polaris Trail Boss 250 2X4
1996 Polaris Trail Blazer 250
1996 Polaris Trail Boss 250 2X4
1997 Polaris Trail Blazer 250
1997 Polaris Trail Boss 250 2X4
1998 Polaris Trail Blazer 250
1998 Polaris Trail Boss 250 2X4
1999 Polaris Trail Blazer 250
1999 Polaris Trail Boss 250 2X4
2000 Polaris Trail Blazer 250
2000 Polaris Xplorer 250 4X4
2001 Polaris Trail Blazer 250
2001 Polaris Xplorer 250 4X4
2002 Polaris Trail Blazer 250
2002 Polaris Xplorer 250 4X4
2003 Polaris Trail Blazer 250
2004 Polaris Trail Blazer 250
2005 Polaris Trail Blazer 250
2006 Polaris Trail Blazer 250