677M06850 Wiseco .020 Piston Kit for Yamaha YZ250 WR250 1992-1998 68.50 mm

Wiseco .020 Piston Kit for Yamaha YZ250 & WR250

This Wiseco .020 oversize piston kit, part 677M06850, measures 68.50 mm and is built for the Yamaha YZ250 and WR250 two-stroke engines from 1992 through 1998.

Overview

This Wiseco .020 piston kit for Yamaha YZ250 and WR250 models restores top-end compression in engines that need a fresh bore. The 68.50 mm oversize piston works with a matching rebore, letting you refresh a worn cylinder rather than replace it. It suits riders and mechanics rebuilding 1992 to 1998 YZ250 and WR250 two-strokes.

Built For Performance

• Forged aluminum construction for strength under high-rpm two-stroke loads
• .020 inch oversize 68.50 mm diameter for use after cylinder reboring
• Kit includes piston, rings, wrist pin, and circlips for a complete top-end rebuild
• Designed to match the 677M series profile for the YZ250 and WR250 engine
• Machined ring grooves for consistent ring seal and compression
• Cross-reference part number 677M06850 for easy verification

Fits These Machines

• for Yamaha YZ250 1992-1998
• for Yamaha WR250 1992-1998

On-The-Job Use

• Top-end rebuilds after cylinder wear or scoring
• Motocross and off-road engine refresh on 1992-1998 YZ250 models
• Trail and enduro servicing on WR250 two-strokes
• Rebore and hone jobs requiring an oversize piston
• Rider or shop-level two-stroke maintenance

Specs At A Glance

Good To Know

Q: Does this piston need a rebore? A: Yes, at .020 inch oversize the cylinder must be bored and honed to match the 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 engines and is not an original manufacturer part.

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