If you have to execute fixes on your own Aprilia RS 125 R then it is always a good idea to possess a Workshop Manual for a guide in case you need to know how to strip off a certain component like the Clutch and install it again in the correct way.
Aprilia RS 125 R Workshop Manuals will give you specific diagnostic information for the car therefore if something is not working it will help you identify what the issue is and methods to repair it. You can then assess if this can be achieved on your own or that the job is too big you are able to book your RS 125 R in to a nearby mechanic.
Aprilia RS 125 R manual