If you need to execute repairs to your Kawasaki EN 400 Vulcan then it is usually recommended to have a Workshop Manual to use as personal reference just in case you need to know proven methods to remove a specific part for example the Gearbox and install it again accordingly.
Kawasaki EN 400 Vulcan Workshop Manuals offers you certain diagnostic info on your vehicle so if something is not working it helps you find out what the situation is and some ways to make it better. You will be able to analyse if this can be achieved by yourself or in case the job is simply too big you can make a reservation for your EN 400 Vulcan in with a nearby repair garage.
Kawasaki EN 400 Vulcan manual