765M05400 Wiseco GP Series Std Piston Kit for Yamaha YZ125 1997-2004 54 mm

Wiseco GP Series Std Piston Kit for Yamaha YZ125

This Wiseco GP Series standard bore piston kit, cross-referenced as 765M05400, is a 54.00 mm forged piston assembly that restores compression and top-end power to two-stroke YZ125 engines.

Overview

This Wiseco GP Series piston kit is a 54.00 mm standard bore replacement built for Yamaha YZ125 two-stroke engines. The forged piston and matched components refresh top-end sealing and compression so the engine pulls cleanly through the rev range. It suits riders and mechanics rebuilding a worn or seized YZ125 top end.

Built For Performance

• Forged piston construction for high-strength durability under two-stroke heat and load
• Standard 54.00 mm bore size for direct replacement of the original piston
• GP Series profile engineered for competitive motocross and off-road use
• Kit includes piston, rings, wrist pin, and circlips for a complete top-end refresh
• Precision machined skirt and ring grooves for consistent sealing and long service life
• Cross-referenced as 765M05400 for easy parts identification

Fits These Machines

• for Yamaha YZ125 1997
• for Yamaha YZ125 1998
• for Yamaha YZ125 1999
• for Yamaha YZ125 2000
• for Yamaha YZ125 2001
• for Yamaha YZ125 2002
• for Yamaha YZ125 2003
• for Yamaha YZ125 2004

On-The-Job Use

• Top-end rebuilds on motocross tracks and practice bikes
• Trail and woods riding where clean throttle response matters
• Racing applications requiring reliable compression across a full moto
• Preventive maintenance when measured piston-to-cylinder clearance is out of spec
• Engine refresh after a seizure, lean condition, or overheating event

Specs At A Glance

Good To Know

Q: Do I need to measure the cylinder before installing this piston? A: Yes, the cylinder bore should be checked for wear and roundness so the correct piston-to-cylinder clearance is confirmed before assembly.

Q: Is this a complete top-end kit? A: It includes the piston, rings, wrist pin, and circlips, but gaskets, bearings, and cylinder work are separate unless otherwise noted.

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