91304-ZVT-B11 Chain Case Gasket - Overview. The 91304-ZVT-B11 Chain Case Gasket is a critical component in Honda marine engine systems. Designed to create a watertight seal around the chain case, it prevents oil leaks and keeps contaminants out, ensuring the reliability and longevity of the engine. As a specifically engineered gasket for Honda-Active Marine engines, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precisely desig