The Japanese do this a lot, you'll find. Yamaha and Suzuki stuff is often interchangable, slightly less so with Honda. Electrical components, switchgear, turn signals, headlight buckets, throttles, levers, perches, even wheels, forks, brake discs and tons of other hardware can be identical between brands if you pay close attention. Hardly a starter motor made is specific to just one bike.
Handy info.