The big Rotax four-stroke single found its way into a remarkably diverse range of motorcycles. Applications ranged from Aprilia and KTM trail motorcycles to the Armstrong and Harley-Davidson military machines and later CCM competition and supermoto models, all shared the same Nippon Denso ignition system. At Rex’s Speed Shop we have been repairing and manufacturing…

The Yamaha SR500 has been around for nearly half a century and, while its ignition system was well engineered, age is now becoming as important as mileage when diagnosing faults. The closely related SR400 presents many of the same challenges. Over many years of repairing SR ignition systems, rewinding stators and manufacturing replacement CDI units,…