Yamaha YZF 250 Extreme Big Bore Kit
Available for the 21-23 and 24-25 Yamaha YZF 250, Athena's new Extreme Big Bore Cylinder Kits with integrated GET Boost module expand the available applications of their Extreme Big Bore Kits lineup, now delivering the next-level performance they are known for to the ever-popular YZF 250.
"This upgrade is engineered to let the latest YZF 250 generation reach its full potential with increased displacement, increased torque and increased power across the entire power curve, without compromises."
The enlarged cylinder with forged piston increases displacement to a true 304 cc, turning the Yamaha into a fuller, more immediately responsive bike with continuous pull across the whole powerband.
"Thanks to the included, pre-configured GET Boost module, there's no need to redo mappings or modify the ECU. It is pure plug & play - install it, start the engine, twist the throttle and feel the difference immediately."
Athena says that its race development programme gives it the experience and results to build Racing Technology that is built to last. By using premium materials such as a high-silicon aluminium cylinder, co-cast steel liner, forged piston and DLC-treated wrist pin the company says it can produce an upgrade kit that is designed to "perform at the limit".
"Even under extreme conditions, the high-seal MLS (Multi Layered Steel) head gasket ensures impeccable sealing thanks to laser-cut stainless steel, delivering total reliability, even when temperatures rise and the engine is under stress.
This performance upgrade kit includes a high-grade aluminum cylinder with an oversized steel liner, a forged performance piston with pin and rings, and all necessary gaskets. Developed through Athena's extensive racing experience, "this kit ensures smooth, powerful, and progressive power delivery."
The included electronic GET Boost module is pre-calibrated for this specific setup. GET Boost installs easily without ECU or wiring modifications with seamless pre-mapped integration.
GET Boost connects directly to the injector and throttle body via a dedicated harness. The module is pre-mapped to deliver safe, reliable performance with a power curve tailored to the new cylinder.
The cylinder is made from high-silicon aluminum alloy with a steel liner fused using Athena's proprietary co-casting process, "ensuring optimal heat transfer and combustion sealing." The forged piston, CNC-machined and coated with molybdenum disulfide, "offers reduced friction and enhanced durability. The DLC-coated pin ensures maximum hardness and reliability."
The included MLS head gasket is laser-cut from stainless steel to ensure perfect sealing and long-term durability, even under extreme conditions. Bore Diameter is 85.00 mm, bore gain is +8 mm, compression ratio is 13.3:1 with 304.15 cc displacement.
ATHENA
