Wiseco WB1157 Bottom End Gasket Kit for Yamaha YZ250

The Wiseco WB1157 is a complete bottom end gasket kit engineered specifically for the 1998 Yamaha YZ250. Designed to meet or exceed OEM standards, this kit supplies everything needed to properly seal your engine's bottom end during a rebuild — ensuring long-term reliability and performance right out of the box.

Key Features:

• Premium gasket materials — manufactured from high-quality materials that meet and exceed OEM specifications, providing an exceptional seal between all critical mating surfaces
• Complete kit contents — includes all gaskets and seals required for a thorough bottom end rebuild, eliminating the need for separate sourcing of individual components
• Engineered for Wiseco crankshafts — designed to ensure full compatibility with Wiseco crankshaft assemblies and OEM crankshaft specifications
• Corrosion-resistant surface treatment — protects components against corrosion and pitting during long-term use or storage, extending the life and strength of the assembly
• OEM-quality main bearings — case hardened for maximum service life and smooth operation at high RPMs
• Caged needle roller bearings — designed to support the highest possible RPM operation
• Shot-peened connecting rod — double-forged design features shot peening, oil slots, and coated bronze thrust washers for reduced stress and improved durability
• Bushed top end rod — upper rod bore is bushed for oil retention and to eliminate pin galling; lower rod bore is case hardened to 58–62 RC for an optimized bearing running surface
• High-quality crank pin bearings — manufactured from hot-rolled steel and case hardened to 58–62 RC for extended assembly life

The Wiseco WB1157 bottom end gasket kit is the professional-grade solution for a complete, worry-free YZ250 engine rebuild. Sourced from reliable, high-quality manufacturers, each kit is built to Wiseco's rigorous engineering standards so you can rebuild with confidence.