The ProX piston kit is intended for piston replacement during an engine rebuild on the 2027 Yamaha YZ 250 F. The dimensions and compression ratio below identify this piston variant.

Specifications

• Standard bore: 77.00 mm
• Piston size: 76.96 mm
• Actual compression ratio: 14.1:1
• Total height: 34.30 mm
• Piston pin hole diameter: 17.00 mm
• Compression height: 11.50 mm
• Boss spacing: 16.00 mm
• Piston head: Flat with raised top
• Valve pockets: 4
• Piston construction: Forged

Cross-Reference OEM Part Numbers

• Yamaha: D05-11631-00
• PROX: 01.2437.B

Vehicle Fitments

• Yamaha YZ 250 F: 2027