605M06900 Wiseco .040 Piston Kit for Yamaha YZ250 WR250 1988-1991 69.00mm

Wiseco .040 Piston Kit for Yamaha YZ250 & WR250

This Wiseco .040 oversize piston kit for Yamaha YZ250 and WR250 models gives your 1988-1991 two-stroke engine a fresh top end, with a 69.00 mm bore matching Wiseco part 605M06900.

Overview

This Wiseco .040 piston kit for Yamaha YZ250 and WR250 two-strokes is a 69.00 mm oversize top-end rebuild component for riders reviving an older machine. The .040 oversize piston kit restores compression and power after cylinder wear, and the piston kit suits anyone honing a worn bore back into shape. Each piston kit is referenced by Wiseco part 605M06900 so you can confirm the exact oversize step before ordering.

Built For Performance

• Wiseco .040 oversize piston sized at 69.00 mm for worn two-stroke cylinders
• Fits Yamaha YZ250 and WR250 two-stroke engines from 1988 through 1991
• Part number 605M06900 stamped to the piston kit for easy identification
• Forged piston construction typical of Wiseco two-stroke top-end kits
• Complete kit format for a straightforward top-end rebuild

Fits These Machines

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

On-The-Job Use

• Top-end rebuilds after a seized or scored piston
• Bore clean-up work when the cylinder is honed to the next oversize
• Motocross and off-road engine freshening on older YZ250 machines
• Trail and enduro rebuilds on WR250 two-strokes

Specs At A Glance

Good To Know

Q: How do I know if I need a .040 oversize piston? A: The oversize step is chosen after measuring the cylinder bore and deciding how much material must be removed to clean up wear or damage. A machine shop can confirm whether the bore should finish at 69.00 mm.

Q: Does this piston kit include rings and a pin? A: Wiseco top-end kits are typically supplied as a complete piston assembly, but you should verify the included components against the listing before ordering. Confirm any additional gaskets or bearings you may need separately.

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