From Motorcycle USA.com:
"New Zealand bike genius John Britten had a dream before he tragically died, that of a 100-hp single-cylinder machine weighing in at just 100 kg (220 lbs). Italian Roberto Crepaldi worked with the Kiwi on the idea and has now progressed to the first stage of trying to turn that dream into reality as mark of respect for his mentor.
The Vun is a road-legal bike made by his company CR&S (Cafe Racers and Sportbikes) and he hopes it is the first step in achieving Britten's dream. The current machine weighs 298 lbs and is powered by a 68-hp Rotax single-cylinder motor, which, while reliable, is not quick enough.
Cue Italian engine manufacturer TM, best known for its kart engines. CR&S have managed to tune a 710cc motor from them to give 75 hp, but they feel there is still another 10 hp to come. This new unit is smaller and lighter than the Rotax powerplant, but Crepaldi feels he can still shave more weight from the bike.
This continued development will be in the shape of a race bike to help sort out handling and suspension as well as overall power and weight. While the Britten's 100-hp/100-kg goal may well still be some way off, it is hoped that this next gestation will be even closer than at present."