808M06640 Wiseco Single Ring GP Series Std Piston for Yamaha YZ250 1999-2024 66.

Piston for Yamaha YZ250

This Wiseco single ring GP Series standard piston fits Yamaha YZ250 machines from 1999 through 2024, cross-referencing 808M06640 at a 66.40mm bore.

Overview

This 66.40mm GP Series piston is made for Yamaha YZ250 owners rebuilding the top end on 1999 to 2024 models. The single ring standard piston restores sealing and compression for dependable two-stroke power. It is aimed at motocross racers and weekend riders who need a reliable replacement piston for their YZ250.

Built For Performance

• GP Series design tuned for high-revving two-stroke performance
• Single ring layout lowers friction for crisp throttle response
• 66.40mm standard bore matches the factory cylinder
• Forged construction for durability under heat and load
• Designed to cross-reference OEM number 808M06640

Fits These Machines

• for Yamaha YZ250, 1999-2024

On-The-Job Use

• Top-end rebuilds during scheduled engine service
• Motocross racing on YZ250 two-stroke machines
• Restoring compression on worn or high-hour engines
• Pre-season freshen-ups before race day

Specs At A Glance

Good To Know

Q: Is this piston a direct replacement for my YZ250 top end? A: It is designed as a standard bore replacement piston for the listed YZ250 model years, so confirm your bore size before ordering. Q: Does the GP Series single ring piston need special break-in? A: Follow normal two-stroke break-in with moderate throttle and heat cycles to seat the ring properly.

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