Nothing puts stress on a motorcycle like an enduro. These long-distance time trials resemble motocross, but rather than following a circuit, an enduro involves a cross-country route of at least 160 miles.
It's also important to remember that this is a time trial, not a race. You don't win by being the fastest, you win by coming the closest to the desired time. Fill up your tank before you start—you have a very long way to go.