This Wossner piston kit features a 56.50mm bore (+0.01 oversize) and is designed for Yamaha YZ125 models from 1983 and 1985. Wossner forged pistons are engineered to offer superior strength and efficient heat transfer from the combustion chamber to the cylinder walls. The elliptical design ensures a uniform bearing surface under heat expansion, distributing thrust loads evenly to prevent piston collapse. Manufactured in Germany.

Features

• Forged construction for increased strength


• Optimized heat transfer to cylinder walls


• Elliptical design for uniform bearing surface and thrust load distribution


• Made in Germany

Specifications

• Bore Size: 56.50mm


• Bore (Actual Measured): 56.44mm


• Display Volume: 83 cm³


• Stroke: 84.00mm


• Clearance: 0.06mm


• Compression Ratio (Wossner): 2-stroke


• Compression Ratio (OEM): 2-stroke


• Compression Height: 30.80mm


• Lock Part Number: CW16


• Pin Part Number: WP036


• Ring Set Part Number: RSB5600

Cross-Reference OEM Part Numbers

• 39W-11-630-00-00


• 55Y-11631-00-94

Vehicle Fitments

• Yamaha YZ125 1983


• Yamaha YZ125 1985