40155M07700 Piston Kit for Yamaha YZ250F 2016-2018 Wiseco Std 77.00 mm 14:1 CR

Wiseco Std Piston Kit for Yamaha YZ250F

This Wiseco standard bore piston kit, part 40155M07700, is a 77.00 mm piston with a 14:1 compression ratio for Yamaha YZ250F engines, restoring stock top-end performance.

Overview

This Wiseco standard piston kit for Yamaha YZ250F models from 2016 through 2018 uses a 77.00 mm piston with a 14:1 compression ratio to refresh top-end power. It suits riders and engine builders returning a YZ250F to stock bore dimensions. Each piston kit for Yamaha YZ250F applications is a direct-fit replacement for the original bore size.

Built For Performance

• 77.00 mm standard bore piston matching the original size
• 14:1 compression ratio for strong midrange and top-end power
• Wiseco part number 40155M07700 for easy verification
• Forged piston construction for durability under race conditions
• Ring, pin, and clip hardware included in the kit

Fits These Machines

• for Yamaha YZ250F 2016
• for Yamaha YZ250F 2017
• for Yamaha YZ250F 2018

On-The-Job Use

• Top-end rebuilds at stock bore size
• Motocross and off-road racing on YZ250F machines
• Restoring lost compression on high-hour engines
• Routine piston replacement during engine service

Specs At A Glance

Good To Know

Q: Is this a standard or oversize piston? A: This is a standard bore piston at 77.00 mm, so it fits a stock-size cylinder that is within spec.

Q: What should be checked before installing a new piston? A: Measure the cylinder bore for wear and taper, check ring end gap, and inspect the wrist pin bearing and valve train while the top end is apart.

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