Those starting enrichment circuits

Do starting enrichment circuits usually work properly on part valve
openings? My CB500 dies immediately if the "choke" is eased further open
whilst idling and I'm wondering if it's a result of me being hamfisted.

 

Are you saying it dies as you go from off to half-on or as
you go from full-on to half-on ?

This time of year, I wouldn't expect to use the enrichener
for more than perhaps a minute at half-on.

If it hardly needs the enrichener, that would seem normal.
If it always needs the enrichener, I'd look for air leaks
and/or crapped up idle jets.

 

You didn't state what specific CB 500 you have, T, S, or 4 so the enrichment
circuits will differ but the bottom line is the same.
Enrichment circuits add fuel to the mixture but they also add air by opening
the throttle valve slightly or opening an air port ( high idle or warm up
throttle position )
The fuel for the system that uses "choke" plates comes from the idle and
transition ( off idle ) circuit. by restricting the amount of air allowed
into the carb a lower pressure area is created, atmospheric pressure acting
on the fuel in the float bowl forces fuel into the venturi at an even
greater rate than when the choke plates are open.
Problems arise when the fuel passages are restricted or plugged with gum and
varnish caused by old fuel being allowed to evaporate leaving behind these
deposits.
Even with the choke plates closed the partially plugged fuel passages can't
supply enough fuel for a cold engine. And when you pull the choke "on"
further, the high idle cam / linkage opens the throttle valves slightly
allowing more air into the intake manifold resulting in a lean misfire.
Recommend dismantling carbs completely and cleaning with carb cleaner making
sure all passages and jets are clear of blockage.