- Explosive power and continuous delivery at all speeds
- Optimised geometry and advanced cooling for superior performance
- Removable cylinder head for customisation and heat dissipation
- Ergal 7075 valves for exceptional strength and reliability
The latest generation Yamaha YZ 125 stands out for its extraordinary engine power and agile chassis, offering responsive acceleration and impeccable cornering. Power delivery is well balanced, providing significant power without sacrificing manoeuvrability. The transmission offers smooth gear changes, allowing the rider to maintain control in all situations.
For those who want to take their Yamaha YZ 125 to the next level, Athena presents the new Big Bore Cylinder Kit, the ultimate upgrade over the standard cylinder, designed to maximise power and fun on the track.
Advanced Technology for Superior Performance
Athena's Big Bore Cylinder Kit increases displacement to 144 cc, unleashing an explosion of power that can be felt from the moment you open the throttle. Thanks to advanced engineering and intensive bench and track testing, this kit transforms every acceleration into an exhilarating experience, with power that continues to grow linearly at all revs and seems to never end.
The Cylinder: Unrivalled Performance
The heart of the thermal group is obviously the aluminium cylinder, designed with optimised geometries to maximise combustion efficiency. The intake and exhaust ports are designed to ensure optimal gas flow. The cooling chambers are designed to prevent overheating even during the most demanding sessions. The Big Bore Athena cylinder maintains smooth and balanced power delivery across the entire rev range, transforming the YZ 125 riding experience into a memorable one.
Detachable cylinder head: Tailored Power
Another strong point is the split cylinder head, consisting of an aluminium outer shell and a bronze inner dome. This configuration also allows for customisation of the squish and compression ratio. Other benefits include improved heat dissipation and a consequent increase in engine reliability and durability, which is essential in an extreme environment such as off-road riding. The dome, which is self-centring and recessed into the cylinder bore, ensures a perfect seal and optimal combustion, for smooth and constant power delivery. Flexibility and superior performance are key aspects, especially on 2-stroke engines where every detail can really make a difference.
Exhaust Partialising Valves: Strength and Reliability
The valves are made of hard anodised Ergal 7075, ensuring resistance to high temperatures and lightness. Designed with extreme precision, these valves ensure a hermetic seal, preventing compression leaks and maintaining combustion efficiency for constant and reliable power.
Complete Kit for Total Reliability
In keeping with Athena tradition, the Big Bore thermal unit includes a high-quality gasket kit, designed to ensure complete installation. Each gasket is made to withstand even the extreme conditions of the track, ensuring a perfect seal and long engine life.
The Ultimate Upgrade for Your Yamaha YZ 125
The Athena Big Bore thermal unit is not just a replacement part; it is a manifesto of pure power and unwavering reliability. By installing this kit, every corner will bring a smile to your face and every twist of the throttle will be a pleasure.
With Athena, your Yamaha YZ 125 will become the perfect weapon for any track, ready to respond with surgical precision and unleash irresistible power.
Explosive power and continuous delivery at all revs
Optimised geometry and advanced cooling for superior performance
Detachable cylinder head for customisation and heat dissipation
Ergal 7075 valves for exceptional strength and reliability
Technical specifications
Bore (mm) 58.00
Displacement (cc) 144.00
Increase (mm) + 4
Net weight (kg) 2.56
Compression ratio 15.4:1
