Standard rear preload should be no3 (rider only) and with pillion I set mine to 5 and go up 2 clicks on rebound. I'm about 13 stone, my missus a bit (don't go there!) less. Setting it softer makes it rock back and forth like a boat when braking/accelerating. Experiment yourself is the best, depends on the weight being carried. Also Google 'yamaha fz1 manual pdf ' and there's loads of info there.
Taksi