Technical information on competition engines for Harley-Davidson motorcycles.
Stage Four Harley-Davidson engines are
"anything goes". If it can be stuffed into a motorcycle chassis, its worth
trying. Time, expert knowledge, special tools and lots of money are required to build a
stage four engine. These are all out race engines, designed for drag racing and other
forms of competition.
These modifications can provide from 120+ horsepower at the rear wheel of a late model
Harley-Davidson motorcycle. For these engines, the horsepower is only limited by the
available money and engineering skills.