NGK B8ES Spark Plug

The NGK B8ES was the definitive spark plug for classic air-cooled Japanese motorcycles. The Honda CB750 K-series, Kawasaki Z1, and Kawasaki H1 Mach III — the machines that invented the modern superbike — all specified the B8ES. The 14 mm thread and 12.7 mm reach were adopted as a de-facto standard across all Japanese engine builders of the early 1970s, making the B8ES one of the first genuine shared-standard components in the Japanese motorcycle industry.