I've been rebuilding all the wiring on my bike, and I got just a bit frustrated with the existing diagrams, so I recreated the official wiring diagram as a color diagram in vector format. I had seen a color wiring diagram for the 750; however, I'm not sure if it was accurate for the '77K. Mostly, I wanted a larger diagram.
For those not familiar with vector diagrams, their primary advantage is that they can be scaled to any size without loss of resolution. To view, edit or print them, you need a vector diagram program, such as Adobe Illustrator. I made the diagram with Illustrator 9.0. I've also included a relatively high resolution (1400x900) JPEG file that can be displayed with any normal image viewer.
I've sized the Illustrator file so that it prints a diagram about 22"x14" (56x36cm) across several US letter-sized pages. Let me know if you have any problems using the vector files. They work for me using Illustrator; however, I was unable to convert them to either CorelDraw or SVG formats.
I created the diagram from the official Honda 1977 shop manual. This original diagram is included in the vector files as a layer toggled "not visible." This layer can be toggled "visible" for comparison purposes. I have done my best to make the diagram as accurate as possible; however, please let me know if you find any errors or discrepancies.