Big Bore Cylinder Kit Φ85 mm，304 cc to increase performance

Bore Diameter (mm)：85.00
Bore Gain (mm)：+8
Compression Ratio：13.3：1
Displacement (cc)：304.15

※Race Use Only Product - Not intended for street use.
※The cylinder head and base gaskets contained in the kit are specifically developed for Athena cylinders kits. Whenever the cylinder kit is disassembled，replace the gaskets with the specific Athena spare gasket kit：DO NOT use OE replacement gaskets.
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Unlock the full potential of your Yamaha YZF 250 with Athena’s Extreme Big Bore Kit，designed to increase displacement and deliver more torque and power across the entire RPM range.
This kit is ideal for riders who want to push the limits of the latest YZF 250 while maintaining its signature agility and responsiveness.
Performance upgrade for Yamaha YZF 250
The 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.
GET Boost module included for optimized performance
The kit features the GET Boost electronic module，developed by Athena’s GET division-renowned for its work with top MXGP and AMA teams. Pre-calibrated for this specific setup，GET Boost installs easily without ECU or wiring modifications，unlocking the full potential of your engine.
Easy installation and seamless 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.
Advanced construction and materials
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.
High-quality gaskets included
The MLS (Multi-layer Steel) head gasket is laser-cut from stainless steel to ensure perfect sealing and long-term durability，even under extreme conditions.
Take your Yamaha YZF 250 to the next level
Athena’s Big Bore Kit with GET Boost is the ultimate upgrade for riders seeking more power，torque，and excitement from their latest-generation YZF 250. Experience the thrill of enhanced performance-on the track or offroad.

Bullet points
Oversized cylinder with high-performance forged piston
Includes pre-mapped GET Boost module for easy install
Advanced materials for superior strength and reliability
Premium gaskets ensure perfect and lasting sealing

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