You mean that curved wire spring? That is a choke unloader. Its function is to open the choke if you happen to go to full throttle while the choke is still in the partially closed position (automatic warm-up position).
The manual choke lever has three positions. Choke off, Automatic, and Choke on. Normally left in center Automatic position.
The Automatic function uses a temp sensor to partially close the electric choke till it warms up a bit. There is a service bulletin telling how to disable the automatic function in some cases where it wants to over-choke when not needed.
