If you wish to undertake adjustments on your own Aprilia SR 50 R then it is always recommended to own a Workshop Manual to use as a reference in case you need to know the best way to strip off a certain component for example, the Drive Shaft and fit it again accordingly.
Aprilia SR 50 R Workshop Manuals are able to offer unique diagnostic guides for the car therefore if something is broken it helps you figure out what the issue is and ways to fix it. You will be able to analyse if this can be achieved yourself or if ever the job is simply too big you could book your SR 50 R right into a decent garage.
Aprilia SR 50 R manual