Yes the starter plunger is part of the "choke" but the choke is actually a starter/starting fuel circuit.
The starter fuel circuit is an enrichener which allows for the uptake of extra fuel when starting a cold engine.
Kawasaki dot com & Partzilla have parts diagrams, but Partzilla is easier to use.
Find your motorcycle in the OEM section. The starter plunger is in the Carburetor parts diagram.
ps: a traditional choke will choke off some of the air to enrichen the fuel/air, so technically it isn't a choke, but the term is still used.
1981 KZ650-CSR. Competition, Sports & Road.