If you need to do maintenance tasks on your own Derbi GPR 50 R then it is always a good plan to have access to a Workshop Manual for personal reference in the event you need to know tips on how to take out a specific part such as the Exhaust and match it again accordingly.
Derbi GPR 50 R Workshop Manuals provides specified diagnostic guidelines on your automobile therefore if something is faulty it helps you understand what the situation is and the best way to resolve it. You will be able to assess if this can be done yourself or that the job is simply too big you are able to make a reservation for your GPR 50 R in with a suitable repair garage.
Derbi GPR 50 R manual