Re: how to use the choke
You are correct. The 'choke plate' is indeed the part you see. Lever up, the plate covers the inlet air opening in the carb. Lever down, the inlet is open.
On a cold engine start it is sometimes beneficial to close the choke either partially or all the way. When the engine starts and after a few seconds the choke should be opened and left open thereafter. Usually you won't need to choke if the engine is warm.
Using the choke makes for an over rich fuel to air mix that can assist starting a cold engine. Depending on carburetor tuning some engines don't need any choke to start, some like a little or a lot.
A lot depends on your fuel/oil mix, outdoor air temperature, humidity, your altitude above sea level, etc. There are many factors that come into play on just how an engine starts and runs or its need for choke use.
After some time you'll discover just what your engine needs for best starting. Experiment and it will tell you.
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