There are some inherent problems here though, as Harley seemingly has admitted with the introduction of the liquid-cooled V-Rod's Revolution motor. Aftermarket companies have been pushing the limits of the design that Harley made famous. Engines are getting bigger and bigger - but not necessarily better. S&S has set out to change this course for good with their new X-Wedge engine design.
Motorcycle-USA has done a very good job of explaining the thinking and technology behind this new engine. I enjoyed reading the article. They highlight the fact that many of the changes to the basic design were made to meet new emissions requirements and add greater efficiency to the twin-cylinder engines. Enjoy the read.