DYNAMIC RACING / 2019-2025 YAMAHA YZ250F 80mm 270cc BIG BORE KIT All in one bolt on kit! You can expect an easy 3-4hp from this kit. And another 1-2 with a good dyno tune. One standout feature of this piston kit is its innovative crown design, which enhances combustion efficiency and delivers improved power output. Combined with a custom DLC-coated wrist pin and specially designed rings, this kit ensures premium durability and performance. A COMETIC gasket kit is included that guarantees a reliable seal. Paired with a high quality Cylinder Works cylinder this kit is incredibly reliable and makes serious power. Kit Includes: -14.7:1 Compression Ratio JE Forged Piston -Cylinder Works 80mm Cylinder (This cylinder has thicker water jackets that prevents cylinder failures, unlike traditional big bores) -DLC Coated Wrist Pin: Reduces friction and maximizes durability and performance -Japanese Ring Pack: Provides a secure seal for enhanced performance -COMETIC 80mm head gasket, cylinder gasket, valve guide seals, exhaust gasket and tensioner gasket For optimal performance we recommend pairing this kit with our Vortex ECU and custom maps.