Carrillo RS1MGNHD-3937 CP Piston Ring Set 3.937" Bore Gas Nitrided

The Carrillo RS1MGNHD-3937 is a high-performance piston ring set engineered for 3.937-inch (100mm) bore applications in powersports engines. Designed by CP-Carrillo — a leader in precision racing engine components — this ring set is built to deliver superior sealing, reduced friction, and long-term durability in demanding performance and racing environments.

Key Features:

• 3.937" (100mm) Bore Size — precision-matched for correct ring-to-wall fit and optimal sealing
• Gas Nitrided (GN) Top Ring — the gas nitriding process produces an extremely hard, wear-resistant surface for improved durability and reduced friction compared to standard chrome rings
• HD Powersports Application — ring configuration specifically engineered for high-performance V-twin powersports engines
• Performance Ring Package — designed to work exclusively with CP-Carrillo performance pistons; not compatible with OEM stock pistons
• Sold as a Single-Cylinder Set — one complete ring set per piston

CP-Carrillo piston rings are manufactured in Japan to exacting tolerances and are intended for use in high-performance and race-built engines. Proper ring end gap measurement and cylinder preparation are essential prior to installation. Always verify bore size and confirm compatibility with your specific CP-Carrillo piston before ordering.