The CB750 K8/F3 manual states:
Remove the right side cover and check the oil level with the filler cap dipstick. Do not screw the cap in when making this check.
mystic_1
Confirming "don't screw it in" on a CB750. On the CB750, the dipstick won't go much deeper into the tank if you were to screw it in anyway as the cap only turns 1/4+ turn or so. But on many wet sump bikes with the dipstick in the filler plug which has several turns of threads, it could make a big difference.
I guess that begs this clarification: I don't screw it in, but I do allow it to drop to its lowest point in the tank's filler neck. What you say to that, Mystic or others?
While it may be true on some bikes that one should screw it in, all bikes that have ever been in my stable are of the "don't screw it in" variety.