Quick look: Athena Cylinder Kits for Yamaha YZ and YZ X 125 – 144cc big bore
Athena has rolled out a complete line of cylinder kits for the Yamaha YZ 125 (22–26) and YZ X 125 (23–26), with three options including the 144cc big bore kit – shush, don’t tell the scrutineers.
With over 50 years experience in off-road, Athena should be a name you’re familiar with. The Italian specialists have a long history in aftermarket products to improve performance and replace or upgrade OEM parts.
Developed by their R&D department to balance reliability, fun and outright performance, the new kits for the YZ125 two-stroke models bring three options for exactly that – replacing the standard parts on either the YZ 125 or X model, or upgrading to the 144cc option for a little more power.

Standard Bore Cylinder Kit – Ø 54 mm, 125cc
Compatible with Yamaha YZ 125 (22–26), YZ X 125 (23–26)
• Direct replacement for OEM cylinder
• Designed for strength and durability
• Smooth, balanced delivery across the rev range
• Precision piston for clean acceleration
• Heat- and vibration-resistant gaskets
Standard Bore Racing Cylinder Kit – Ø 54mm, 125cc
Compatible with Yamaha YZ 125 (22–26), YZ X 125 (23–26)
• Reworked intake and exhaust ports for sharper response
• Lightweight, single-ring flat-top piston with Oil Dots
• Modular head with bronze insert for optimised squish, compression and heat dissipation
• Racing exhaust valves with reinforced geometries
• Supplied with all gaskets – plug & play track-ready kit

Big Bore Cylinder Kit – Ø 58mm, 144cc
Compatible with Yamaha YZ 125 (22–26), YZ X 125 (23–26)
• 144cc displacement for maximum power
• Aluminium cylinder with modular head and bronze dome
• Adjustable squish and compression ratio
• Ergal 7075 hard-anodised exhaust valves for sealing and reliability
• Lightweight piston for quick throttle response
• Heavy-duty gasket set tested against thermal and mechanical stress
The full Athena cylinder kit range is available now via www.athena.eu or through authorised dealers.