Like Grainbelt said, most any bike can be ridden on crappy roads if the pace is reasonable. One exception is mud. I never rode in much mud, and that was on purpose. And my size and long legs did a lot to make this possible. The biggest issue in the rocks was lack of ground clearance. This was the only trip that was that extreme. I mostly limited myself to gravel roads. I did ride some pretty good dirt, rocky trails in the North Carolina mountains, along with some other 1st and 2nd gen FZ1s. Again, just went slow.
Here's two more pics from Nevada.
When the road quality reached this level the riding got a lot more fun.
Proper jetting and a 3 degree timing advancer gave that bike more low end torque than you would expect from an I4. I could lug down to 2500 rpm when I had to and still pull out of it.
AllBlackPearl, have you checked out the FZ1 Owner's Association at www.yamahafz1oa.com/forum
? It's a great group of people and FZ1 resource.