If you choose to conduct fixes on your own Yamaha YB 50 then it is usually a good plan to have access to a Workshop Manual to keep just for personal reference in case you want to know ways to strip off a specific part like the Brake Pads and install it again adequately.
Yamaha YB 50 Workshop Manuals offers clear detailed diagnostic guidelines for the car or truck therefore if something is playing up it will help you work out what the issue is and how to repair it. After that you can assess if this can be achieved on your own or if the job is simply too big you could make a booking for your YB 50 in with a decent friendly mechanic.
Yamaha YB 50 manual