4694M09500 Wiseco Std Piston Kit 95mm 13.5:1 for Yamaha YZ426F WR426F 2000-2002

Wiseco Standard Piston Kit for Yamaha YZ426F and WR426F

This Wiseco standard piston kit is a 95mm forged piston assembly with a 13.5:1 compression ratio for the Yamaha YZ426F and WR426F, cross-referenced to Wiseco part 4694M09500.

Overview

This Wiseco standard piston kit for Yamaha YZ426F and WR426F provides a forged replacement piston at 95mm bore with a 13.5:1 compression ratio, matching the Wiseco 4694M09500 reference. Owners rebuilding a 2000 to 2002 YZ426F or WR426F top end use this kit to bring compression and sealing back to spec. The Wiseco piston kit suits riders who want a durable forged piston in a direct-fit assembly.

Built For Performance

• Forged aluminum piston construction for strength under high compression
• 95mm standard bore size matches the factory cylinder diameter
• 13.5:1 compression ratio for strong combustion pressure and power output
• Wiseco part number 4694M09500 for easy cross-reference and verification
• Kit format includes the piston and matching components for a top-end rebuild
• Designed specifically around the Yamaha YZ426F and WR426F engine architecture

Fits These Machines

• for Yamaha YZ426F 2000
• for Yamaha YZ426F 2001
• for Yamaha YZ426F 2002
• for Yamaha WR426F 2000
• for Yamaha WR426F 2001
• for Yamaha WR426F 2002

On-The-Job Use

• Top-end rebuilds on 2000 to 2002 Yamaha YZ426F motocross bikes
• Trail and enduro engine refresh projects on the Yamaha WR426F
• Restoring compression after piston wear, scoring, or ring failure
• Maintenance builds where an OEM-equivalent bore size must be retained

Specs At A Glance

Good To Know

Q: Is this a genuine Yamaha piston? A: No, this is a Wiseco piston kit referenced by part 4694M09500, not an original Yamaha component. It is designed to fit the 2000 to 2002 Yamaha YZ426F and WR426F.

Q: Does the standard 95mm size require boring the cylinder? A: A standard bore piston is sized to the factory cylinder diameter, so it is used when the cylinder is within specification. Measure bore wear and clearance before assembly, since oversized pistons are needed once a cylinder is worn or damaged.

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