Is it possible to convert a cv carburettor motorcycle to fuel injection?, the bike is a UK spec kawasaki gt55?

You can but, it'll be expensive... Why not buy a good used Yamaha C3 Scooter (called the Giggle and Vox in other parts of the world.) It already has electronic fuel injection, with a computer and all of the same electronics that modern automobiles possess. Mine runs 46mph ang gets 117mpg on regular gasoline.