A tamper and theft detection alarm system is provided for a motorcycle, bicycle or other two-wheeled vehicle. The alarm system is configured to detect vehicle movement or theft by monitoring the tilt angle of the vehicle, and once a change in the tilt angle is detected, notifying the rider or owner by wireless cellular telephone. In certain embodiments the motorcycle or bicycle alarm system is additionally provided with a Global Positioning System (GPS) receiver configured to receive signals from the United States govemment's Global Positioning System (GPS) satellites or other similar global position locating systems and then interpreting the satellite signals to calculate the vehicle location in global coordinates and then providing these coordinates via synthesized speech to the owner via wireless cellular telephony.