Hey man, I had a Kawasaki Vulcan motorcycle when I was young, too. Since we lived in the countryside, I often rode off-road. This meant that some parts of the motorcycle wore out quickly, so I spent a lot of time in the garage repairing the bike. I can give you some advice. First, here is the manual you requested: https://manualmachine.com/kawasaki/en450/7768546-service-manual/. I used it myself when I was repairing mine. If the problem is with the engine or fuel system, you can fix it at home. If so, you can contact me via private message. However, I strongly recommend contacting a specialized repair service. While you can do some things yourself, if there are problems with the electronics, it is better to leave it to the professionals.