Namura Size B Standard Bore 66.36mm Piston Kit for Yamaha YZ250 1999-2024 66.4mm

Namura Size B Standard Bore 66.36mm Piston Kit for Yamaha

This standard bore piston kit is designed to replace the original piston in Yamaha YZ250 engines from 1999 to 2024 with a 66.4mm bore (size B).

Overview

The Namura Size B standard bore piston kit is a direct OEM replacement for Yamaha YZ250 two-stroke engines. This piston kit restores compression and power, featuring precision-machined components for a perfect fit. It is designed for riders who need a dependable piston for stock displacement.

Built For Performance

• Precision-machined from high-strength aluminum alloy
• Includes piston, rings, wrist pin, and circlips
• Standard bore 66.36mm piston for stock cylinder size
• Durable ring package for consistent seal
• Lightweight design for minimal reciprocating mass

Fits These Machines

• for Yamaha YZ250 (1999-2024)

On-The-Job Use

• Ideal for routine top-end rebuilds on YZ250 engines
• Restores factory compression for trail riding and motocross
• Commonly used in preventive maintenance rebuilds

Specs At A Glance

Good To Know

Q: Is this piston kit compatible with a stock cylinder? A: Yes, this standard bore piston fits a stock 66.4mm cylinder with no overbore required.

Q: What is the difference between size A and size B? A: Size B pistons are slightly larger than size A, used when the cylinder is within tolerance but requires a slightly larger piston for proper clearance.

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