Is this your first experience with carbureted engines?
There is no computer for the engine, and the carbs are dumb and tuned for normal operations. A cold engine is not considered normal.
The fuel in the A/F mixture condenses on cold engine internal bits, which makes their hydrocarbons unavailable for pairing with the oxygen. You have to supply an extra rich mixture to compensate. IE: choke.
A cold engine does not burn its fuel efficiently, so less energy is available to spin the crankshaft. Further, a closed or partially closed choke reduces the amount of oxygen getting to the chambers, changing its breathing characteristics. At equivalent settings of the throttle, directly controlled by the twist grip, the engine operates at a lower RPM when cold, if able.
Some carbs have a fast idle cam to up the mechanical idle setting when the choke is actuated. Some Hondas don't have this fast idle cam. Early models had a throttle friction adjust that would hold the throttle at a higher setting (against the return spring), if the operator didn't want to keep his hand on the throttle to keep it running. When Honda Lawyers figured out that people were using this feature as a cruise control and losing control of their bikes, Honda discontinued the throttle friction adjust, to limit liability.
It is normal to need choke for cold start up, and/or partial choke while the engine temp rises to normal. It is also normal for it to not idle at the same RPM when cold as when hot.
Now, if you wish to add an exhaust gas probe and computer link it to adjustable jets, then you can remove some operator skill needed for engine operation over a wide range of Outside Air Temperatures.
Cheers,
