Wiseco WPC139 Crankshaft and Complete Bottom End Rebuild Kit with Gaskets Fits: Yamaha YZ450F 2003-05 Wiseco crankshaft bottom end kit contains everything you need to complete your rebuild the right way, the first time- crankshaft and connecting rod, all applicable bearings, and complete bottom end gasket kit made to meet or exceed OEM Wiseco connecting rods are double forged from a dedicated forging and feature shot peening, oil slots, and coated bronze thrust washers; caged needle roller bearings to provide the highest possible RPM Bottom end gasket kits are made from premium materials, exceeding OEM standards, to provide exceptional seal between critical mating surfaces; main bearings are case hardened for maximum life and smooth operation at high RPM's Top end of rod is bushed for oil retention and eliminates pin galling; the bottom end rod bores and crank pin bearings are case hardened to 58-62 RC to optimize bearing running surface and extend the lifetime of the assembly