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 What is the process for sending an invention or idea to someone for consideration? How can I get parts and service for my Porter Cable product outside North America? What does the "LR" indicate in the 690LR model number? Comments 0 comments Please sign in to leave a comment.