Athena 85mm Big Bore Kit

Description The standard Yamaha engine is considered one of the best in the first part of power delivery: the initial thrust is exceptionally powerful, even though it is within the medium and high steady states, and strong initial progression seems to stabilize a lot.

Athena's Big Bore Extreme increases the displacement up to 304 cc, bringing the bike to have a very strong, effective and consistent engine output over the entire arc of the power delivery curve.

Extensive experience in the Offroad and Racing sectors has allowed the Athena R&D Department to create something that was not yet present on the market: a Big Bore Cylinder Kit with Ø 85 mm steel barrel dedicated to 250cc offroad bikes for an increase of displacement never achieved before, without making any changes to the engine blocks!

The entire kit guarantees maximum performance, better delivery, greater torque at low and medium steady states, better reactivity and - at the same time - the same reliability as original parts, thanks to all the technical devices resulting from the challenge won by the Athena R&D team: all this is combined with the proverbial good handling of a 250cc Offroad for a simply exceptional driving experience.

Bullet points

Ø 85 mm bore: the maximum increase ever

No crankcase machining needed

Racing Forged Piston with fully open boxed bridged design and anti-friction coating

Aluminum alloy Cylinder with Steel Cylinder Liner