Namura .040 Over Bore Top End Repair Kit for Yamaha YZ250 2002-2024 67.4mm

.040 Over Bore Top End Repair Kit for Namura

This top end repair kit is designed for the Yamaha YZ250, providing a .040 over bore size of 67.4mm to restore cylinder compression and performance. It serves as a complete replacement for worn top end components, including piston, rings, wrist pin, and circlips.

Overview

This .040 over bore top end repair kit from Namura is a comprehensive rebuild solution for the Yamaha YZ250 from 2002 to 2024. It includes a high-quality piston and ring set at 67.4mm bore, ensuring reliable power restoration for off-road and motocross use. The kit is engineered to match OEM specifications, making it a direct fit for your Yamaha engine rebuild.

Built For Performance

• Precision-machined piston from 4032 aluminum alloy for strength and heat dissipation
• Plasma-moly ring set reduces friction and improves cylinder sealing
• Proper wrist pin and circlips included for secure installation
• Bore size of 67.4mm ensures exact .040 over clearance for worn cylinders
• Compatible with stock cylinder after machining to .040 over specification

Fits These Machines

• For Yamaha YZ250 (2002-2024)

On-The-Job Use

• Motocross and enduro racing requiring frequent top end rebuilds
• Trail riding where cylinder wear necessitates oversized piston
• Restoring power after excessive hours on worn piston and rings
• Competition use where .040 over bore maximizes displacement within cylinder limits

Specs At A Glance

Good To Know

Q: Does this kit require cylinder boring? A: Yes, the cylinder must be machined to .040 over bore (67.4mm) to accept this piston. Always measure your cylinder before ordering.

Q: Is a Namura piston as good as OEM? A: Namura pistons are manufactured to strict tolerances using quality materials, offering a reliable alternative for rebuilds at a competitive price point.

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