Namura .020 Over Bore Top End Kit for Yamaha Big Bear 250 2007 2008 2009 71.5mm

Namura .020 Over Bore Top End Kit for Yamaha Big Bear 250

This top end kit restores compression and performance in Yamaha Big Bear 250 ATVs from 2007-2009, featuring a .020 over bore (71.5mm) piston assembly for worn cylinders. It includes rings, wrist pin, and circlips.

Overview

The Namura .020 over bore top end kit is designed for Yamaha Big Bear 250 models from 2007 through 2009, offering a precise 71.5mm piston for cylinder repair. This kit provides all necessary components to refresh the top end, restoring lost power and reducing oil consumption. Whether you are rebuilding a worn engine or upgrading performance, this top end kit delivers reliable fitment and durability.

Built For Performance

• Precision-machined 71.5mm piston with .020 oversize for accurate cylinder fit
• High-strength rings reduce blow-by and improve compression
• Heat-treated wrist pin withstands high engine loads
• Includes circlips for secure piston pin retention
• Namura quality construction ensures consistent tolerances

Fits These Machines

• for Yamaha Big Bear 250 2007
• for Yamaha Big Bear 250 2008
• for Yamaha Big Bear 250 2009

On-The-Job Use

• Trail riding and recreational ATV use
• Utility tasks like hauling and light towing
• Engine rebuilds to extend service life
• Restoring compression in high-mileage machines

Specs At A Glance

Good To Know

Q: Does this kit include a cylinder? A: No, this is a piston and ring set; the existing cylinder must be bored to .020 over size to match.

Q: Can I install this kit without professional help? A: Top end work requires basic mechanical skills and proper tools; we recommend having a qualified technician perform the installation if you are not experienced.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.