That part is called a bimetalic spring with housing the purpose of this part is to coil up in cold temperature and uncoil when heated, that cause the choke blade to open and close.
It is a carburetor where the engine coolant is routed through the choke system of the carburetor. When the coolant is cold the choke will close. As the engine coolant heats up it opens the choke.
Manual choke
Sounds like the coolant temperature sending unit (CTS sensor) It detects the current temperature of the radiator fluid and determines whether it should choke the throttle body or not. It usually screws into the intake near the thermostate housing. Trace the top radiator hose to the intake / thermostate housing location and you will see it. Usually has 2 wires going to it.
no
A common cause for an automatic choke to stick in a 318 Dodge truck is a dirty carburetor. A spray can be used to clean the carburetor to stop the choke from sticking.
The choke control should have a cable attached to it that attaches to the choke on the carburetor at the other end. If you have no movement at the carburetor when you move the choke lever, look for the cable to be disconnected at either the choke lever or the carburetor.
Choke Cleaner
An automatic choke is connected to the carburetor on small engines. To get a new automatic choke, a new carburetor will need to be purchased. It is easier to install a manual choke and less costly. Kits for this are sold at most automotive repair stores.
I assume your question was "do you ride an Xr100 with the choke on?". In response to that the answer is no. If you are having to run it with the choke on, that is an indication of clogged jets in the carburetor which will require removing the carburetor, disassembling, cleaning, reassembling and reinstalling on the bike.
The idle control is the choke and its located right next to the throttle body on the cylinder heads, there are two screws, one is for the choke and one does nothing, the one that's for the choke is the closest to the back of the engine. there are two hoses conecting to the air intake that are in the way so you will have to take off the intake then you will be able to see it clearly.
grab it around the throat (carburetor) and choke it until it starts.
The carburetor has an electric choke that is possibly shorted.