What is the motor diameter of the Porter Cable 7815 router? Wilson October 30, 2020 21:30 Updated The motor diameter for the 7815 is 4.2". Related articles Can I use hot water in my pressure washer? What is the warranty on my drill? What is the decibel rating of the model 7765 rotary hammer? 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.