Back in 1987, Yamaha wanted to test a two-wheel drive motocross bike and this very special YZ490 was born. Using all mechanical components specially made in England, the bike was tried and tested, then eventually went into a private collection. We got our hands on this unique 34-year-old air-cooled YZ to see how it works, and put it through its paces in its natural environment – on the mud and on slippery hills.