NGK Spark Plug Stock # 4551

The NGK Spark Plug Stock #4551 (BR9HS-10) is a resistor-equipped spark plug engineered for reliable ignition performance across a wide range of small engines, lawn equipment, and light-duty marine applications. This 14mm threaded plug with a 0.500-inch reach and gasket seat design provides the precise heat range and electrical characteristics needed for consistent cold starts and stable combustion under varying load conditions.

NGK's resistor technology suppresses radio frequency interference, protecting onboard electronics while delivering reliable spark under temperature extremes. The gasket seat construction ensures a secure, maintenance-free fit without additional sealing compounds. The BR9HS-10 spec—heat range designation and electrode geometry—has been validated across OEM specifications for single- and multi-cylinder engines where stock replacement or scheduled maintenance is required. Proper electrode gap and installation torque are critical; reference your engine manual for exact specifications before installation.

This plug suits operators and technicians performing routine maintenance on outdoor power equipment, small engines, and recreational watercraft where OEM-equivalent performance is the priority. Whether maintaining generator sets, pressure washers, portable pumps, or outboard motors, the NGK BR9HS-10 delivers the thermal stability and electrical integrity expected from a premium spark plug without premium pricing. Stock this part for rapid field replacement or fleet maintenance operations.

NGK spark plugs are recognized across the small-engine and marine industries for consistent performance and OEM cross-compatibility. The BR9HS-10 represents a direct fit for applications originally specified with this heat range, making it a straightforward parts-interchange choice for technicians familiar with NGK's thermal and resistance specifications.