Sorry for replying so late as I could not get enough time on weekend to reply you, although I read your post at that time. Now coming to the sound well again as I said to that other guy the sound clip would be helpful.
Apart from that as in the morning the car starts and runs on auto choke its rpms are around 1200-1500 whereas in normal warm engine idle condition they are 700-750 so these extra 500-750 rpms do increase the sound that is not otherwise heard but if somebody sits inside a warm engine car and revs it to 1200-1500 rpms you might hear them again if you open the bonnet.
Another thing is that since the throtle is not pressed while the auto choke is running and the auto choke fools the tps to believe it is open more than it actually is so only the fuel going to the cylinder is increased not the air and the mixture is richer. This richness in mixture can cause an increase in sound.
Amidst all this discussion you should not forget that your car is around 250,000kms driven and you are comparing it to a less than 100,000kms driven car. If we make a list of parts that need to be replaced after 80,000 or 100,000 kms inside an engine and compare it with the parts that you have replaced you will find that you have replaced only 20-30% rest all original now suppose if a part had to be changed at 80,000 kms your car has covered 3 times that mileage so basically some parts inside your engine are not replaced and running as they came from honda factory whereas they should have been changed 2-3 times. These parts in your car have an extra 150,000-180,000 kms on them when compared with a less than 100,000km driven car.
P.S Dont get me wrong by engine parts I do not mean to say that pistons and valves need replacement after 80,000km neither the cam or crank need replacement. Its just those small bearings and bits and pieces attached to the main components in an engine that need replacement. These parts may not create a problem for like 500,000kms or may go bad after 40,000kms.
Once there was a car at my mechanics and I was there to complain about these type of hissing and kirr kirr and etc sounds in my car he showed me that car, believe me it was less than 40,000 kms driven and had all those sounds which I was complaining about but the intensity of those sound was quite lower like 20-30% compared to my car. P.S the car was brought by the same owner to the mechanic who bought it 0 meter and he was changing oils at 2500 kms, also the mechanic opened its tappet cover for the first time. Now I will tell you what my mechanic told. He said that since your car is starting and running well and smooth you should not worry too much about these sounds because in pakistan even the air is not pure so how can the cars run perfectly and sound less. And believe me his advice has proved right because some sounds are still present in my car that were there when I purchased the car and honda people said that your engine is finished and since than allhamdullilah my car has done around 30,000 kms and temperatures ranging from -2 to 48 and from 0 feet above sea level to around 8500 feet above sea level.
In the end my conclusion is as follows.
Record that sound and upload or send me a clip, I will try to analyze in super slow motion. Check for other symptoms like engine starting when cold and response of the engine. Thirdly check engine and ac generator belts etc they might be the culpirt. Even if after all this practice you are unable to figure out the case, sit back and relax you have driven your car 250,000kms and have taken most of the juice out of it dont compare it to the do sheezas out there with less than 100,000kms on their odo