...but to suggest these old models need any choke whilst riding, is misleading.
Hard to believe the ignorance proudly professed here. Still more opinion presented than science.
Internal combustion, carbureted engines have had choke plates for as long as i remember. There is nothing special about Japanese motors and carburetors that change the laws of physics for them.
Manual choke preceded the automatic chokes, which operated based on temperature. Cars and bikes need choke to run normally when cold. Even the 1937 chevy had a manual choke and a throttle knob on the dash. Latter, engines had a single choke knob the applied choke and throttle simultaneously like some of the latter SOHC4s. Then automatic chokes became standard. They apply full choke when cold and gradually remove choke as the engine warms up. Many engineers are far more clever and aware than many individuals who may have better skills in other matters which don't require an understanding of physics.
Doesn't the CB400 have a fast idle cam on the choke lever? I know the 77 CB750 models do. Those chokes are variable in operation, too.
Choke and partial choke enrich the mixture when operated. Cold engines don't atomize fuel well, and enrichment is required to make power. They are inefficient when cold, so they can't maintain a fixed idle speed setting of the warm engine. These are principles based on physics, rather than human emotion driven opinions.
Modern engines use a computer to sense conditions and adjust mixtures appropriate to present conditions. The computer for the SOHC4 is located 2-3 ft above the seat. And some of these work far better than the others. But, it's this computer that is
usually capable of adjusting the choke to make the engine comply with throttle demands.
It is no harder to reach down and poke the choke lever than it is to reach down and twiddle the idle knob. And in some ways easier.
If you tweak the idle knob, you are compensating for lack of engine power with centrifugal inertia. And it inhibits engine breaking to slow down.
In the end, it's a matter of how well you can learn to operate your machine. Certainly, if you are not competent enough to poke the choke lever while riding or stopped, then don't do it. But, I fear for your survival as a competent motorcycle rider. In some cases, perhaps a culling is a good thing. As, there are those that simply shouldn't ride a motorcycle as they can never be safe. Public transport is a safer alternative.
If you chose to waste gas with a stationary warm up run, that's your choice. But, for 20-30 years I have easily avoided that practice with my CB550s. Never did I feel unsafe. And we all know how important "feelings" are...in order to make the machine behave as we feel.
Cheers,
