I am thinking about upgradeing my yamaha sr250 1980 drum brakes to disc and would like to know what other yamaha parts would fit and what parts do I need to get to do this upgrade any help I get would be greatfully recieved and also many thanks for all help with this

your best bet is to get a newer sr with disk brakes and use that or swop the parts over.you will need wheels with discs calipers pipes master cylinders fork legs swinging arm rear brake pedal plus frame brackets to mount master cylinder and brake pedal stop light switch and mounting quite a big job really. you could up grade you drums with a skim and new modern linings, you might be able to get a twin leading shoe front brake off another yam that would fit your existing wheel. given the performance of the sr i would go for the skim and new linings