546M08750 Wiseco .020 Piston Kit for Yamaha YZ490 1984-1990 87.50 mm

Wiseco .020 Piston Kit for Yamaha YZ490

This Wiseco .020 over piston kit for Yamaha YZ490 replaces the stock piston with an 87.50 mm bore size and carries OEM cross-reference 546M08750 for accurate fitment.

Overview

This Wiseco .020 piston kit for Yamaha YZ490 gives your two-stroke engine a fresh top end with an 87.50 mm bore. Each kit is built to restore compression and power on 1984-1990 YZ490 models. Riders rebuilding a worn or scored top end will find this piston kit a direct-fit solution.

Built For Performance

• 87.50 mm bore size for .020 over applications
• Forged aluminum construction for strength under high heat
• Precision-machined skirt and ring grooves
• OEM cross-reference 546M08750 for fitment matching
• Complete kit with piston, rings, pin, and clips

Fits These Machines

• for Yamaha YZ490 1984
• for Yamaha YZ490 1985
• for Yamaha YZ490 1986
• for Yamaha YZ490 1987
• for Yamaha YZ490 1988
• for Yamaha YZ490 1989
• for Yamaha YZ490 1990

On-The-Job Use

• Top end rebuilds on worn or seized YZ490 engines
• Bore-over service when the cylinder needs a .020 hone
• Motocross and off-road riding where compression matters
• Restoring power on high-hour two-stroke machines

Specs At A Glance

Good To Know

Q: Do I need to bore my cylinder for this piston? A: Yes, this .020 over piston requires the cylinder to be bored and honed to 87.50 mm for proper clearance.

Q: What is included in this piston kit? A: The kit includes the piston, rings, wrist pin, and circlips needed for a top end rebuild.

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