Blown Ignition Coil on the 85 -4K

During this shakedown ride, I planned to complete a 15-mile loop to bring the Shovelhead motor up to operating temperature and check for any additional leaks. The shorter 4-mile runs had gone flawlessly so far. However, about 10 miles into the ride, the motor began to backfire and eventually cut out as the 35-year-old ignition coil failed. Here’s a detailed account of the failure on what was otherwise a perfect shakedown ride.