Cometic C9870 Cylinder Base Gasket 3-13/16" Bore .020" Thick SLS

The Cometic C9870 is a high-performance Single Layer Steel (SLS) cylinder base gasket designed specifically for Harley-Davidson Evolution 1340cc Big Twin engines. This precision-engineered gasket features a 3-13/16 inch bore diameter with a .020 inch (0.51mm) thickness, providing optimal sealing and proper compression for big bore applications.

Key Features:

• Single Layer Steel construction with rubber coating for superior sealing
• 3.8125 inch (3-13/16") bore size accommodates Evolution Big Twin big bore cylinders
• .020 inch thickness allows for precise deck height adjustments
• High-quality materials developed for maximum performance tolerances and longevity
• Fuel-resistant materials that will not creep, crack, or become brittle
• Made in the USA with Cometic's renowned quality standards
• Sold as a pair for both cylinders

Compatible with 1984-1999 Harley-Davidson Evolution 1340 Big Twin models including FL, FX, FXST, FXR, and FLHT series. This gasket is ideal for street performance applications and engine rebuilds where precise base gasket thickness is critical for proper engine geometry and compression ratios.