If you have to do maintenance tasks for your Yamaha TZR 125 then it is always a good idea to have a Workshop Manual to keep just for personal reference in the event that you need to know how to take off a specific component for instance the Drive Shaft and install it again accordingly.
Yamaha TZR 125 Workshop Manuals can offer you exact diagnostic details for the car or truck so if something is wrong it will help you find out what the problem is and how you can resolve it. You will be able to decide if this can be done on your own or in the event the job is just too big you can actually book your TZR 125 right into a nearby mechanic.
Yamaha TZR 125 manual