Twin-cylinder motocross bikes are rare and successful ones are even rarer. The best known twin was the 1980 Gilera Bicilindrica. It was raced by Italian GP racer Franco Perfini and on occasion by M

The Yamaha YZ125, introduced in 1974, has the longest production run of any motocross bike in the world.Over the years, the 125-cc, two-stroke liquid cooled engine has evolved greatly.The current v