The easiest way to ensure the old carburettor is working perfectly is to replace it with a new one. however, if a budget has to be maintained, then an overhaul of the carb assembly will work out a lot less expensive if time is not counted.
Replacing all the jets would probably be enough to restore full performance, but look closely at all the wear, corrosion and contaminated prone internal components to make sure that nothing is left to chance.
More related parts you may wish to consider:
TIP: Sonic cleaning of the carburettor by a specialist will help make sure all the internals are up to scratch - sometimes this will bring an old but not particularly well used carb back to an acceptable operational standard. Add as may items as you wish to the same shopping cart, new gaskets, O-rings and adjustment springs 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. So ensure the part-numbers you order are correct for your model.