Donny’s 740-page book, Donny’s Unauthorized Technical Guide to Harley-Davidson, 1936 to Present: Volume I: The Twin Cam, guides the reader on a surefooted journey to a thorough understanding of the H-D Twin Cam. Petersen’s insight paired with hundreds of graphics, pictures, and charts makes complicated technical subjects easy to grasp, especially for the motorcycle novice. His down-to-earth writing examines what’s right, what’s wrong, and what’s just okay about the TC 88, TC 96, TC 103, and CVO 110 Twin Cam powertrains. Donny solves problems. This is the definitive bible on all aspects of the Harley-Davidson by the world’s most-read Harley technical journalist. Available at Amazon.com and DonnyPetersen.com.