Yamaha YZ 250 F (CG 39) [2017-2018] - forged pistons

PROX forged pistons for Yamaha YZ 250 F

The PROX forged piston is designed for the Yamaha YZ 250 F (CG 39) of the full 2017-2018 model year range. As a forged aluminum version, it combines the proven material selection with a specific aluminum alloy that helps reduce friction and support reliability.

Function and execution

The piston shape has a flat crown with a raised top and 4 valve pockets. Piston compression is standard; the stated compression is 13.5/1. The piston is manufactured in OEM-equivalent quality and is tailored for use in the 4T engine.

Technical data

• Brand: PROX
• Piston Type: Forged
• Material: aluminum
• Diameter Ø: 76.97 mm
• Letter oversize: C
• Oversize: +0.02
• Piston compression: standard
• Compaction: 13.5/1
• Rings Quantity: Set
• Stroke: 4T
• Piston shape: Flat crown with raised top / 4 valve pockets

Vehicle assignment

Suitable for Yamaha YZ 250 F (CG 39), built between 2017 and 2018. When making the selection, the complete vehicle type, the year of manufacture, the diameter of 76.97 mm as well as the marking C and oversize +0.02 must be taken into account.