CYLINDER FULL KIT 85mm YAMAHA YZ 250F 21-23, ATHENA P400485100105 304CC BIG BORE, (Piston included)

Athena big bore cylinder full kit (part reference P400485100105) for Yamaha YZ F 250 applications, increasing displacement via an 85 mm bore to 304 cc. Supplied with high-grade cylinder, forged piston with pin and rings, complete gaskets, and a pre-mapped GET Boost module that installs without ECU or wiring modifications to suit this configuration.

Features

• Big bore cylinder kit to increase displacement and deliver higher torque and power across the RPM range

• Cylinder manufactured from high-silicon aluminium alloy with an oversized steel liner

• Steel liner fused using co-casting process for heat transfer and combustion sealing

• Forged piston, CNC-machined

• Molybdenum disulphide piston coating to reduce friction

• DLC-coated piston pin for hardness and durability

• Piston rings and pin included

• Complete gasket set included

• MLS head gasket, laser-cut stainless steel

• GET Boost electronic module included, pre-calibrated for this kit

• GET Boost installs without ECU or wiring modifications

• Dedicated harness connects to injector and throttle body

• Pre-mapped to suit the new cylinder configuration

• Piston included

• Athena part reference: P400485100105

Specifications

• Bore diameter: 85.00 mm

• Displacement: 304.00 cc

Vehicle Fitments

• YAMAHA YZ F 250 cc (2021–2023)