NC23 engine in CB400 super four

[91cb-1]

Hi all. not exactly a question relating to the -1 but my brother just bought a new CB400 superfour. it's 1992 as opposed to his last one which was 93. this one has the added tittle of porject big one. on his last super four the engine number was NC27 which i believe was the standard engine number for the superfours. the chassis number is NC31 which was the same as the old one but in the new bike the engine number is NC23, which unless i'm very much mistaken is the same as our very own -1. it looks like the japanese mark two engine as it's all blacked out but other than that it is the exact same except for the cylinder block as it is not suspended from the frame this way. I'm some what baffled. was this the standard engine used for the superfour big one back in 92? 92 was the initial year of manufacture for them so perhaps they used the forever reliable NC23 engine but i don't know. also if this was the case does it mean that the gears are gear driven or chain driven? i know if it was just a replacement engine the likelyhood is that the gears are gear but if they altered the engine for the big one then they may have replaced the cams with chain drive.
if anyone had any idea i would be gratefull for the information.

[a_morti]

To the best of my knowledge- nc23 is the number for all 400/4 engines in the same family
- nc23, 27, 29, 31, 33, etc. I don't (didn't) think any engine numbers started nc27, you might want to check that.

Nc23 engines are not all the same and not imterchangable.  Later ones did indeed have a camchain once mfg costs became more important than engineering beauty.

[91cb-1]

Well then that solves the riddle thanks morti

[oldsmoker]

Aren't the super fours air cooled? Is your brothers bike water cooled?

The NC23 engine # came in the CB400RR/Areo. Very early -1s had that ENGINE# before it was changed to NC27 ( which my -1 has ) That number change may indicate the change in the cam spec from Jap spec (NC23) to US spec (NC27). At any rate both have gear driven cams.Your brothers may very well be gear driven also.