Federal, state and local laws all have their say in how you must transport your firearms. Before you transport your firearms using a motorcycle, you should check your local laws. According to the California Department of Fish and Game, "a motorcycle is a vehicle and the laws governing the possession of loaded shotguns or rifles in vehicles apply the same as if you are in a car or a truck."
One thing that they all have in common is that you must have them unloaded and in an approved case. Each state has its own definition as to what constitutes a case. Illinois insists upon the case being some type of container that is designed specifically to carry a firearm and capable of being zipped, snapped or locked closed. Most states have very similar definitions.
Unload your gun and leave the action open.
Insert the rifle into your locking rifle case and then place the ammo in its locking case. Lock both cases.
Use the bungee cords to secure the rifle case to the back of your motorcycle. Secure the ammo case to the back of the motorcycle as well.
Ensure that the safety is on before you begin unloading the rifle. Always use extreme caution when handling firearms.