Athena introduces the new Big Bore Extreme cylinder kit range, developed for the most popular off-road platforms from the leading brands. This range has been engineered to take a 250 to a displacement that reaches and exceeds 300 cc, opening up a new frontier in off-road performance. 

This is not a simple stock replacement, nor a conventional displacement upgrade: it is the most advanced evolution of Athena big bore technology. For over 50 years, we have been developing mechanical and electronic engine components. With Big Bore Extreme, we decided to go even further, transforming an existing platform into something bigger, fuller and more aggressive, without compromising the agility and handling that make a 250cc so unique. 

Because this is not just about bore size. It is about an engine that responds faster on the throttle, delivers stronger drive and feels more commanding out of the corner.

Because every engine has a limit. We chose to rewrite it.

Big Bore Extreme was born from a clear decision: to engineer each kit with a dedicated, application-specific approach, rather than adapting a generic solution to different bikes.

Behind every cylinder kit is the work of Athena’s R&D department, which develops custom geometries, fitments, and technical solutions for each application. This know-how has been built through decades of experience in OEM development, collaboration with some of the world’s most renowned off-road teams, and a deeply rooted Made in Italy culture of engineering and technical expertise.

And it does not stop at the design stage: every kit is tested in-house, from the dyno to the track, to turn engineering into a real riding sensation.

The drive and character of a 450. The lightness and agility of a 250.

It starts with a 250 platform, with targeted bore upgrades to increase displacement and deliver more torque, stronger low- and mid-range response and a fuller power delivery.

You feel the advantage as soon as you ride: the presence of a larger displacement, combined with the agility, light weight, and handling of the original platform.

In other words: more drive out of the corner, quicker response, and more engine in every twist of the throttle.

A bike that stays compact, but plays in a different league.

The power takes a big step up. The installation stays smart.