Namura .040 Over Bore Piston Kit for Yamaha Big Bear 400 & 1993-1999 Kodiak 84mm

Namura .040 Over Bore Piston Kit for Yamaha

This Namura .040 over bore piston kit is designed to replace the factory piston in Yamaha Big Bear 400 and 1993-1999 Kodiak models, restoring compression and performance with an 84mm bore diameter.

Overview

The Namura .040 over bore piston kit is a direct replacement for Yamaha Big Bear 400 and Kodiak ATVs from 1993-1999, featuring an 84mm bore size to refresh worn cylinders. This .040 over bore piston kit includes the piston, rings, and wrist pin for a complete top-end rebuild.

Built For Performance

• Cast aluminum piston with precision-machined ring grooves
• .040 inch oversize allows cylinder wall cleanup without reboring to next size
• Includes all necessary rings and wrist pin for installation
• Manufactured by Namura, a trusted aftermarket brand for powersports

Fits These Machines

• for Yamaha Big Bear 400
• for Yamaha Kodiak 1993-1999

On-The-Job Use

• Rebuilding top-end on Yamaha Big Bear 400 ATVs
• Restoring compression on higher-mileage Kodiak engines
• Performance rebuilds requiring oversize pistons

Specs At A Glance

Good To Know

Q: Does this piston kit require any machining to install? A: Yes, the cylinder must be bored to .040 inch over the standard size to accommodate this piston; always have the work done by a qualified machine shop.

Q: Can this kit be used in other Yamaha models? A: It is specifically designed for Yamaha Big Bear 400 and Kodiak 1993-1999 with 84mm bore; other models would require different sizing and fitment verification.

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