Harley Davidson has been able to expand their product line without investing a penny in R&D by acquiring Buell. Buell offers Harley the unique opportunity to design a contemporary engine, and they really need to as the problems with sticking their infamous 45 degree V-twin in a sport bike are abundant. The fact that Erik got that thing in the frame qualifies him for a National Science Foundation grant.
Harley’s use of a simple motor that they slightly redesign every hundred years is a wise move from a manufacturing perspective. There’s not much in the way of retooling and parts are never a problem. In the field, they are easy to work on because of their simplicity. In fact, the only prerequisite to being an HD mechanic is the ability to perceive consciousness.
Anyway, Buell represents an opportunity for HD to create a new mill - maybe even an excuse to experiment with water cooling - without upsetting the tribe. A worthy choice might be something similar to the engine Aprilia is using - a 60 degree V Twin with two counterbalancers. This type of engine represents a good compromise between engine size (length) and vibration. And the narrower V allowed Aprilia to use throttle bodies that share the same shaft for the throttle plates - no synchronizing needed.
Unlike contemporary Japanese twins, the Aprilia mill shakes and vibrates subtly, making you feel like you're riding a real motorcycle. A similarly designed HD engine would preserve enough of the characteristics that are the hallmark of the motor company’s current product as well as represent a natural evolution and refinement of where their product stands today. Then, after the cruiser boom is over in 10 years and people are buying mower kits for their Road Kings, HD has a place to go with their new technology.
So, the best engine for a Buell is still a Harley Davidson - just not one that is in production. Hopefully in these boom times, HD is setting a little scratch aside for R&D so they don’t have to rely on another act of congress to bail out their myopic approach to motorcycle production.