If you wish to undertake adjustments to your Bultaco Metralla 250 GT then it is usually a great idea to possess a Workshop Manual to use as reference in case that you need to know simple methods to take off a particular part much like the Brake Discs and install it again the right way.
Bultaco Metralla 250 GT Workshop Manuals are able to offer specified diagnostic details with regards to your car or truck therefore if something is not working it helps you identify what the issue is and some ways to fix it. You can then determine if this can be achieved yourself or if the job is too big you could book your Metralla 250 GT into a suitable car garage.
Bultaco Metralla 250 GT manual