Mark, Caution 60/70tlra 2002

Carburettors do wear eventually, and air intake reed valves similarly require attention after time and use, replacing internal parts like the float, jets and adjustment screws/springs with new components usually gets everything back into shape.
But, also check that the fuel being used is not contaminated, with water or particulates and is fresh - fuel has a relatively short shelf life and will soon go off - the smell will inform as well as anything else.
An alternative, short and easy way to refurb the carbs is to simply fit complete new carburettor assemblies - more costly but saves a lot of time. Time also has value?
Other carburettor/intake related parts you may wish to consider:

6H1136410294
6884121701
9321039ME4
68813621A1
6881362400
6881361000
688W000400
6H11444002
6H11441302
6H11430107
6H11430108
6H11430207
6H11430208
6H11430307
6H11430308
6921459001
6H11494775
6H11494339
6H11494818

Add as many items as you wish to the same shopping cart, new screws 9858006550 9858004014 9858004008 bolts 9731306030 9708006012 & washers 9020906M05 9299006600 for example, and still only pay the same single fixed price shipping cost.
Pro-workshop gasket sealant, 08C70K0234M to help achieve a professional level of engine building expertise.

This component may have other applications within the Yamaha marine engine model range, so please make sure you order the correct part number/s for your application.