key
Two possibles:
On my Honda the key code is on the back of the ignition switch. The switch can be taken apart with a little time so it's not easy to do for someone who is trying to steal your bike.
Two: I lost the key to my honda and had a locksmith come out and mfg a key from a blank he had. Took him about 30 minutes of tapping, cutting, etc. but it works.
I always carry a spare in my wallet now. For both the Honda and the Yamaha.