4650M09200 Wiseco Std Piston Kit for Yamaha YZ400F WR400F 1998-2000 92mm 13.5:1

Wiseco Std Piston Kit for Yamaha YZ400F/WR400F

This Wiseco standard bore piston kit for Yamaha YZ400F and WR400F models delivers a 92mm bore at 13.5:1 compression, cross-referenced to part 4650M09200.

Overview

This Wiseco standard piston kit is a forged replacement piston built for Yamaha YZ400F and WR400F four-stroke engines. The 92mm standard bore piston maintains a 13.5:1 compression ratio for strong, reliable power across the rev range. Riders freshening up a worn top end will find this Wiseco piston kit a direct-fit option for their Yamaha 400cc thumper.

Built For Performance

• Forged aluminum construction for high-strength durability under race conditions
• 92mm standard bore size matching the original cylinder dimension
• 13.5:1 compression ratio for crisp throttle response and strong power
• Precision-machined ring grooves for consistent ring seal
• Cross-reference part number 4650M09200 for easy verification
• Includes piston, rings, wrist pin, and circlips in a complete kit

Fits These Machines

• for Yamaha YZ400F 1998-2000
• for Yamaha WR400F 1998-2000

On-The-Job Use

• Top-end rebuilds on YZ400F and WR400F motocross and enduro bikes
• Standard bore service when the cylinder remains within spec
• Trail and track riding where reliable compression matters
• Restoring power lost to a worn or scored stock piston

Specs At A Glance

Good To Know

Q: Do I need to bore the cylinder for this piston? A: No, this is a standard bore piston, so the cylinder should be within factory spec and typically honed only. Verify your cylinder bore and taper before ordering.

Q: What is included with this kit? A: The kit ships with the piston, rings, wrist pin, and circlips for a complete top-end rebuild. Check your service manual for torque specs and ring gap during assembly.

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