This book is full of great information. However, it is sorely lacking relevant photos and diagrams. The photos it contains are purely a self-indulgence of the author or publisher, and are of little to no use to the reader at all.
For example, I found it very frustrating to be reading about the differences between various drive trains or engine types and, instead of showing examples of those things, which would help tremendously for the uninitiated (i.e. the book's audience), there would be a photo of a random old Harley, Indian, etc. that didn't illustrate the text.
Proper photos and illustrations would have made this book great.