If you have to do maintenance tasks on your own Yamaha RD 250 then it is always recommended to have access to a Workshop Manual to keep just for personal reference in the event that you want to know methods to remove a particular part including Clutch and fit it again in the correct way.
Yamaha RD 250 Workshop Manuals can offer you certain diagnostic wisdom with regards to your vehicle therefore if something is not working it will help you figure out what the problem is and some ways to correct it. You will be able to evaluate if you can do this yourself or if ever the job is too big you can still make a booking for your RD 250 right into a suitable mechanic.
Yamaha RD 250 manual