Riders of the purple serge

   Motorcycle cops on Yamaha Viragos are a regular presence on Cuban roads. The Virago, the first V-twin cruiser-style motorcycle from a Japanese manufacturer, was built from 1981 to 2007. It's a handsome bike.
   Moto Guzzi and Jawa models are also said to have been used by the Cuban police.
And those form-fitting, purplish uniforms? Well, they're distinctive.