Bridgestone Riders' Championships 4 2004 Valentino Rossi 2005 Valentino Rossi 2008 Valentino Rossi 2009 Valentino Rossi Yamaha Motor Racing is the official factory team of Yamaha in MotoGP . The team currently compete under the name of Fiat Yamaha . It founded in 1999 following the retirement of Wayne Rainey ,