Donny Petersen offers the real deal in performancing your Harley-Davidson Twin Cam. Graphics, pictures, and charts guide the reader on a sure-footed journey to a thorough H-D Twin Cam performance understanding.

Petersen's insight makes technical issues understandable even for the novice.
Donny simply explains what unfailingly works in performancing the Twin Cam.

This is the second volume of Petersen's long-awaited Donny's Unauthorized Technical Guide to Harley Davidson 1936 to Present. This twelve-volume series by the dean of motorcycle technology examines the theory, design, and practical aspects of Twin Cam performance.

Donny studied privately with Harley-Davidson engineers, having worked on Harleys for over 35 years. He founded Toronto's Heavy Duty Cycles in 1974, North America's premier motorcycle shop.

Donny has ridden hundreds of performanced Shovels, Evos, and Twin Cams across four continents doing all of his own roadside repairs. He has acquired his practical knowledge the hard way. Donny has the privilege of sharing his performance secrets the easy way. Donny will walk you through detailed performancing procedures like headwork, turbo-supercharging, nitrous, big-inch Harleys and completing simple hop-up procedures like air breathers, exhausts, and ignition modifications.

Donny Petersen feels honored to share the wealth of his motorcycle knowledge and technical expertise.