If you have to undertake maintenance on your Honda CB 400 N then it will always be a good plan to have access to a Workshop Manual to use as personal reference if you want to know how you can take out a particular component for example the Exhaust and install it again accordingly.
Honda CB 400 N Workshop Manuals will give identifiable diagnostic guides with regards to your vehicle so if something is faulty it helps you determine what the situation is and how to repair it. After that you can assess if this can be done on your own or in case the job is simply too big you are able to make a reservation for your CB 400 N in with a trusted car garage.
Honda CB 400 N manual