If you choose to perform repairs on your own Yamaha XT125R then it is usually a great idea to have access to a Workshop Manual to use as personal reference if perhaps you need to know the way to take out a certain component for example, the Wheel Bearing and match it again in the right way.
Yamaha XT125R Workshop Manuals will give exact diagnostic information for the car so if something is wrong it will help you ascertain what the problem is and the way to fix it. You can then analyse if you can do this on your own or in case the job is too big it is possible to make a booking for your XT125R in to a nearby friendly mechanic.
Yamaha XT125R manual