If you need to do maintenance tasks to your Hyosung GT 650R then it will always be recommended to have access to a Workshop Manual to keep just for reference in the event you want to know ways to strip off a particular part for instance the Brake Discs and install it again safely.
Hyosung GT 650R Workshop Manuals will give you exact diagnostic information with regards to your car or truck so if something is not working it can help you determine what the issue is and some ways to correct it. Then you are able to evaluate if you can do this on your own or in the event the job is just too big you are able to book your GT 650R in with a decent friendly mechanic.
Hyosung GT 650R manual