Refurbishing the brake callipers is a job that should not be put off. The pistons wear, the seals break down and corrosion, external and internal, takes a toll along with physical/accident damage to vulnerable components.
Whatever parts you may require, rest assured that top quality, factory supplied replacements are all available here at CMS, at a reasonable price point and with rapid, reliable shipping.
Other related parts you may wish to consider:
1SDF581T00
90109065F3
1SDF580U01
1S6W004700
1SDF582400
37PF581100
1S6W005700
1SDF580T01
BL1F331700
1SDF582W00
1SDF580W11
1SDF591700
1SDF591900
1SDF591110
1SDF592410
1SDF580900
Add as many components as you wish to the same shopping cart, new disc bolts 90109083G4 for example, and still only pay the same single fixed price shipping cost. Please be aware that this component may have other applications within the Yamaha model range unconnected with braking components; so do check the part-numbers ordered are correct for your model.