NGK Spark Plug Stock # 3922

The NGK Spark Plug Stock # 3922 is the BR6HS standard-reach spark plug engineered for reliable ignition across a wide range of small-displacement engines, from vintage motorcycles to compact automotive applications. As a mechanic, you'll recognize this as NGK's workhorse plug—designed for engines where stock factory specifications call for a proven, long-life electrode design. This plug exists to deliver consistent spark under everyday driving conditions without the premium cost of exotic materials, making it ideal for budget-conscious enthusiasts maintaining original equipment or restoring classics.

NGK's BR6HS features a solid nickel-alloy center electrode with a traditional copper-core design that provides efficient heat transfer away from the firing end, preventing electrode wear and pre-ignition fouling common in high-compression or modified engines running lean. The ceramic insulator is engineered to maintain proper heat range, ensuring the spark plug operates in the thermal sweet spot—hot enough to burn off deposits, cool enough to prevent electrode erosion and gap growth over thousands of miles. Standard 14mm thread pitch with a 3/8-inch hex socket makes installation straightforward on stock equipment without specialty tools or adapters.

Mechanics and DIY builders rely on the BR6HS for carbureted engines, older fuel-injection systems, and small-bore displacement platforms where precision heat range matching is critical. This plug suits riders and drivers who prioritize dependable starting, clean idle, and resistance to fouling in engines that see varied load conditions. For proper fitment, verify your engine's original spark plug specification against the NGK cross-reference chart—mismatched heat ranges can cause performance loss or engine damage. Replace as part of routine maintenance every 10,000–15,000 miles, or when gap wear exceeds 0.040 inches on standard-duty applications.