Cometic C3178-EST Top End Gasket Kit for Yamaha 98mm Bore

• Constructed from spring steel or graphite

• Spring steel gaskets are made from a stainless steel shim design coated with a .0001" thickness of silicone on both sides

• Graphite material is impervious to fuels, coolants and oils

• Engine case rebuild gasket kits include all gaskets needed for a lower end rebuild (base gasket not included)

The Cometic C3178-EST Top End Kit is designed for Yamaha engine applications requiring a 98mm bore gasket solution. This kit provides the essential sealing components needed during top-end service, helping support reliable compression, controlled fluid retention, and proper engine assembly.

Manufactured by Cometic, the C3178-EST is intended to help simplify gasket replacement during cylinder, piston, and related top-end work. Its application-specific design supports accurate fitment for compatible Yamaha engines, making it a practical choice for engine rebuilding, maintenance, or performance-focused upgrades.

Use this kit when replacing top-end gaskets as part of a complete service. Confirm the engine application, model year, and required bore specification before installation to ensure compatibility. Professional installation and adherence to the engine manufacturer's torque and assembly procedures are recommended.

Brand: Cometic
Part Number: C3178-EST
Application: Yamaha
Bore Size: 98mm
Product Type: Top End Gasket Kit
Unit of Measure: Kit

Features:

• Designed for Yamaha engine applications
• Fits engines with a 98mm bore
• Supports top-end gasket replacement and engine service
• Application-specific Cometic design
• Supplied as a complete kit