What is the motor diameter of the Porter Cable 7815 router? Support September 30, 2022 18:54 Updated The motor diameter for the 7815 is 4.2". Related articles Can I use hot water in my pressure washer? What is the decibel rating of the model 7765 rotary hammer? Where can I find a service center to repair my tools? What is the process for sending an invention or idea to someone for consideration? What can cause premature pad failure? Comments 0 comments Please sign in to leave a comment.