If you need to undertake maintenance tasks to your Yamaha TT R 125 then it is always recommended to have a Workshop Manual to keep just for a guide in case you want to know tips on how to strip off a certain part for example Exhaust and fit it again properly.
Yamaha TT R 125 Workshop Manuals will give identifiable diagnostic info for your car so if something is not working it will help you identify what the problem is and tips on how to resolve it. You can then analyse if this can be done by yourself or if ever the job is too big you are able to make a booking for your TT R 125 in with a nearby repair garage.
Yamaha TT R 125 manual