Old Photograph for "Sepia Saturday"

I thought I'd post a picture of my Grandfather, Charles Langan O'Maley of Gloucester, Massachusetts, and 3 of his fellow police officers from the Gloucester Police Department on their new Harley Davidson ? motorcycles. Can any members out there let me know if these are Harleys? The picture was taken at Stage Fort Park in Gloucester in 1931. I remember as a kid back in the 1960's having "Popper" pull this picture off of the shelf and having me "guess" which one was him! He later became the Captain of the police department (before they had chiefs) and is mentioned throughout the book "Behind The Badge" by Ingersoll and Foote. The book is an interesting listing of the actual police logs for Gloucester including back in the days of prohibition. Pretty rough and tumble town back then! My Grandfather is second from the left.

Other officers as noted on the back of the photo are Left to Right:
Wilkinson
Chas L O'Maley
John J. Coyle
George W. O'Maley