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

.040 Over Top End Kit for Yamaha Big Bear 400 & Kodiak 84mm

This .040 over top end kit includes piston, rings, wrist pin, and gaskets to restore engine compression and performance for Yamaha Big Bear 400 and 1993-1999 Kodiak ATVs with a bored cylinder.

Overview

Designed as a direct replacement .040 over top end kit for Yamaha Big Bear 400 and Kodiak ATVs, this oversized kit restores lost compression and power after cylinder boring. It includes a high-quality .040 over piston, rings, and wrist pin for a reliable rebuild. Ideal for owners looking to refresh their engine top end with a slightly larger bore.

Built For Performance

• Precision-machined .040 over piston matches the increased bore size
• High-strength rings provide consistent sealing and oil control
• Includes all necessary gaskets for a complete top end overhaul
• Wrist pin and circlips are heat-treated for durability
• Balanced piston design reduces vibration during operation

Fits These Machines

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

On-The-Job Use

• Trail riding and recreational off-road use
• Farm and ranch utility tasks requiring reliable power
• Hunting and outdoor expeditions where engine dependability is critical
• Restoring top end performance on high-mileage ATVs
• Rebuilding engines that have been bored to .040 over size

Specs At A Glance

Good To Know

Q: What is included in the top end kit? A: The kit typically includes a piston, rings, wrist pin, circlips, and necessary gaskets for a complete top end rebuild.

Q: Do I need to hone the cylinder before installation? A: For an overbore kit, the cylinder must be machined to the corresponding oversized dimension and honed to achieve proper ring seating.

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