Replacement Parts

Replacement Gasket Set: Custom made in USA by Cometic Gasket. Sized to fit the +2mm bore of the 78mm big-bore kit. Head gasket is OEM-style MLS (Multi-layer steel) with embossed sheaves and nitrile coating for a reliable seal. Base gasket is a custom thickness (thinner than stock) to bring quench into the optimal range for maximum performance and detonation protection. 

Replacement Piston Ring Set: These should be installed in a freshly honed cylinder and gapped to 0.012-0.013" for the top ring (T1) and 0.015-0.016" for the second ring (T2). See diagram for ring end-gap orientation. 

Class 10 JIS Stud Nuts: The OEM stud nuts are single-use parts (they're liable to strip if reused). Why replace weak parts with weak parts? We offer Class 10 JIS nuts that are significantly stronger than the OEM Honda parts. We include these with our 301cc piston kit and complete big bore kit, but if you need spares, here you go. 

As a reminder, the stud nuts should be torqued to 38 foot-pounds. Tighten the bolts in steps (we do 15, 25, and then 38 foot-pounds) in a criss-cross pattern.