from the factory, the fuel door locks are not keyed specific. if it is a used bike, no telling what the original owner did. the suggestion for the push button door is spot on....
Like, if you're out for a ride & need gas, just ask somebody to borrow their key for a second.
....... that worked for me.
.... had taken off for a ride ... got low on gas & ... no key
... rode by a bar & there was a Softie out front
........ pulled in, found the rider & asked if he could open my fuel door
.... shur nuff, opened right up, bought the man a beer & then headed for the gas station.