Realistically, thieves who see an opportunity generally take it. An unattended and unprotected motorcycle is an extremely easy target for a thief looking to get in, get the goods and get out.
The Motorcycle Safety Foundation suggests that one of the first things a rider should do after parking is lock the ignition and remove the key. Make it obvious when you lock the forks and/or disk brakes with locks that have brightly colored tags.
If you happen to be riding with other motorcycles try locking your bikes together when they’re stationary. This follows the old “strength in numbers” rule that could actually save your belongings. In the event that you’re traveling alone, lock your bike to an object that is stationary that cannot be easily dismantled. Big cities are known for their “trick street signs” that thieves rig to be easily removable with the ability to ride off on you motorcycle.
As far as your motorcycle’s paperwork, try not to keep any of this stored on the motorcycle itself. Keep your bike registration and insurance identification card on YOU when you ride and leave your title at home.