That's my guess. It would be easy enough to test by clamping off the crossover line and see what happens.

I can think only that it was a cost saving measure but by the time they redesigned and produced the parts then added them to the parts system the saving must have been meagre to say the least.

The short answer is "I don't know." However they did this with the late CB72/77 models so probably the answer is "yes".

Originally they were connected to the air filters. (The filters had suitable nipples but apparently the connection is unnecessary as the later air filters had no nipples.) Here's a video with an explanation which seems plausible.

https://youtu.be/Vce9k1nsQx8

I have a CB77 with a marginally higher serial number that was first registered in 1966 so yours probably was too. My wiring harness tag reads '1965' as well but I think they date the manufacture of the harness. Keep in mind that Honda did not use model years at the time.

It might be possible but it would be very awkward. The problem is that you need to open up enough space to remove the top cover and I expect that just dropping the engine is the best way to do that.

Oops.

Give this a try.

https://drive.google.com/drive/folders/ ... sp=sharing

Here's a screen shot from a parts manual. I have no information beyond this.