If you wish to carry out adjustments for your Yamaha XT 660 R then it is usually recommended to own a Workshop Manual for reference in the event that you want to know the best way to strip off a particular component for instance the Wheel Bearing and install it again correctly.
Yamaha XT 660 R Workshop Manuals gives you precise diagnostic guides on your automobile so if something is wrong it helps you work out what the situation is and how you can resolve it. After that you can decide if this can be achieved by yourself or that the job is simply too big you are able to book your XT 660 R in to a trusted garage.
Yamaha XT 660 R manual