The meaning of dream of being a passenger on a motorcycle depends on your reaction to the dream. If you are happy and loved it then it means escape from your current problems. It symbolically represents freedom. It also means you will meet someone whom you can trust.
Seeing dream of being a passenger on a motorcycle and you are surprised, terrified and want to get out means you will face problems in life due to the actions of other people. The dream is also asking you to take the control of your life and not allow others to decide the direction of your life.
Basically the dream is asking you to do a postmortem of your life and decide whether you are on the right direction.