Refurbishing the master cylinders is just one of those jobs that cannot be put off. The pistons wear, the seals break down and corrosion, external and internal, takes its toll along with physical/accident damage to hoses and other 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:
Add as many components as you wish to the same shopping cart, new screws 9870704012 nuts 9560706200 & bolts 9201706035 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 the master cylinders; so do check the part-numbers ordered are correct for your model.