Harley-Davidson has long pioneered... well, nothing new to be honest. But, that is not necessarily a bad thing in the eyes of their customers. I tend to agree that when a design works, there is no good reason to change it. That seems to be the design theory over at Harley-Davidson. They have been building bikes the same way since they started building them. The one constant that separates Harley's from everyone else is the V-Twin engine. The 45 degree, twin cylinder, single crank-pin, air-cooled engine has been a hallmark for as long as any of us can remember.
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.