ATHENA BIG BORE CYLINDER KIT Ø58MM YAMAHA YZ 125 2022-2027

Athena Big Bore Cylinder Kit Ø58 mm Yamaha YZ 125 2022-2027

The Athena Big Bore Ø58 mm cylinder kit for Yamaha YZ 125 from 2022 to 2027 increases engine displacement to 144 cc, delivering greater power, stronger throttle response and progressive power delivery throughout the RPM range. Developed for motocross applications, it combines advanced engineering, high-quality materials and extensive dyno and track testing.

The aluminium cylinder features optimised geometries and intake and exhaust ports designed to improve gas flow and combustion efficiency. The water jackets are engineered to manage engine temperatures during intensive use. The modular cylinder head combines an aluminium outer shell with a bronze inner dome, allowing squish clearance and compression parameters to be adjusted. The self-centring dome, recessed into the cylinder, provides precise sealing and promotes consistent combustion. Exhaust power valves manufactured from hard-anodised Ergal 7075 combine low weight, heat resistance and durability. The kit also includes a gasket set for installation.

• Brand: Athena
• Range: Big Bore
• Compatibility: Yamaha YZ 125 2022-2027
• Cylinder bore: 58 mm
• Bore increase: +4 mm
• Displacement: 144 cc
• Compression ratio: 15.4:1
• Net weight: 2.56 kg
• Aluminium cylinder with optimised intake and exhaust ports
• Modular cylinder head with aluminium outer shell and bronze inner dome
• Self-centring dome for precise sealing
• Hard-anodised Ergal 7075 exhaust power valves
• Gasket set included

• Increases displacement to 144 cc for greater power and acceleration
• Smooth, progressive power delivery throughout the RPM range
• Improved combustion efficiency through optimised cylinder geometry
• Cooling system designed for demanding track conditions
• Adjustable squish and compression parameters through the modular head
• Durable, heat-resistant exhaust power valves
• Gasket set included for installation