
Ducati, Aprilia and KTM are all in the frame, with the first being the most credible. Team red has had a prototype road-going V-four engine -- a development from its MotoGP bike (pictured) -- in the works for some time, but financial dramas have held back its release.
The company would no doubt like to not have a second false start on this theme: In 1964 it developed a V-four road bike, but sadly never put it into production.
Meanwhile the story that Aprilia has been working on a V-four has been around for a while, and Motorcycle News in the UK claims the company has confirmed it will produce such race version in 2008 and a production bike for 2009.
The KTM rumour has some legs, simply because the company was working on a V-four project for MotoGP - well, until it ran out of money. This is one that falls into the "believe it when you see it" basket.