605M06850 Wiseco .020 Piston Kit for Yamaha YZ250 WR250 1988-1991 68.50mm

Wiseco .020 Piston Kit for Yamaha YZ250 & WR250

This Wiseco .020 overbore piston kit for Yamaha YZ250 and WR250 models (1988-1991) rebuilds the top end with a 68.50 mm piston, cross-referenced to 605M06850.

Overview

This Wiseco .020 piston kit for Yamaha YZ250 and WR250 two-strokes from 1988 through 1991 gives you a fresh top end with a 68.50 mm overbore. The .020 size restores cylinder bore dimensions after wear and keeps compression where it belongs. This piston kit for Yamaha YZ250 and WR250 riders is a practical choice for a scheduled rebuild or a motor that has lost its snap.

Built For Performance

• 68.50 mm diameter, .020 in overbore
• Forged aluminum construction for strength under load
• Wiseco 605M06850 kit reference
• Ring and pin hardware included for a complete top end
• Works with the cylinder bore renewed to .020 oversize

Fits These Machines

• for Yamaha YZ250, 1988-1991
• for Yamaha WR250, 1988-1991

On-The-Job Use

• Top end rebuilds on two-stroke motocross bikes
• Restoring compression on high-hour engines
• Trail and off-road riding where dependable power matters

Specs At A Glance

Good To Know

Q: Does this kit require boring the cylinder? A: Yes, the .020 overbore size means the cylinder must be machined to match the larger 68.50 mm piston before assembly.

Q: Is this an original Yamaha part? A: No, this is a Wiseco piston kit made for Yamaha YZ250 and WR250 fitment and is not an original manufacturer component.

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