Twin Power 046504 Oil Pump Check Ball for 1937-1999 Big Twin Replaces H-D 8866

The Twin Power 046504 is a replacement oil pump check ball designed for Harley-Davidson Big Twin engines from 1937 through 1999, excluding the 1999 Twin Cam. This precision 3/8-inch steel check ball directly replaces Harley-Davidson OEM part number 8866.

The oil pump check valve plays a critical role in engine lubrication. When the engine is not running, the check ball seals the oil pump to prevent oil from draining out of the oil tank and flooding the lower end of the engine. When the engine starts, oil pressure opens the check valve, allowing oil to flow freely through the lubrication circuit. A worn or degraded check ball can result in wet sumping — oil pooling in the crankcase — which is a common maintenance issue on older Big Twin engines.

Key Features:

• Direct replacement for Harley-Davidson OEM part number 8866
• 3/8-inch check ball for oil pump check valve application
• Compatible with 1937–1999 Big Twin engines (excluding 1999 Twin Cam)
• Covers Knucklehead, Panhead, Shovelhead, and Evolution engine families
• Restores proper oil pump check valve sealing function
• Manufactured by Twin Power to OEM specifications

This check ball is a straightforward, cost-effective component for an oil pump rebuild or wet-sump repair on classic and vintage Harley-Davidson Big Twin motorcycles.