Spark plugs can ignite leaner fuel mixtures, but only by increasing spark energy. Unfortunately, these high voltages erode spark plug electrodes so fast, the solution is not economical. By contrast, ...

There's something oddly satisfying about pulling an old spark plug out of an engine, but what do you do with the plug once it's out? Maybe you're having second thoughts about changing the spark plug ...

Harley-Davidson’s Milwaukee-Eight engine carries four spark plugs across just two cylinders, a setup that strikes many riders ...