Hard to believe but there's a 60° v-Twin motorcycle that claims 324 pounds wet. Lots of hand laid composites and state of the art engineering concepts.
So what if it's made of cheese, it's a lightweight v-twin innitt?
Just stating that it isn't asking too much to build a bike like Lukas has outlined. It should be easily achievable.
The bike is easy, the engine, notsomuch..
Aprilia, BRP, Rotax, KTM, and a few others have been working on it for a while.