A Student's First Bike - '81 Custom restomod

[Needforsteve]

It's a mess of weathered parts and mangled wiring, but I've finally bought my first motorcycle and joined my first motorcycle forum!  I'm an Automotive Mechanics student and in training at a local shop but I've wanted to get myself into a bike for a while now. Here it is...



An '81 CB750C with 30,000 indicated miles. Picked it up for a song and it'll even start and run with no more than a screwdriver across the starter relay contacts. Well, it doesn't run very nicely, but it runs. The plan is to clean up as much as possible; keep the tank probably and rear fender, head/tail lamps and running gear. The frame seems solid and I like the wheels. The rest is up in the air.

Now here's where the fun stuff comes in and where I'll probably need all the help I can get ; the wiring is fairly terrible. I mean, maybe not totally shot but it's been mucked with a bit. Here, take a look...



The first of several little nuggets; the taillight harness has been completely hacked off and wired in, quite randomly, to a toggle switch (cutting the light for a nighttime getaway?) All of that mess is coming out. I believe I've found the taillight and rear turn signal harness though...



I believe these to be the tail/rear turn signal harness and the rear brake light switch wiring minus the terminal. Is this correct?

Also, the turn signals. There are none. Replacing them is a-given (NC requires them), but the problem is the wiring. Things in the turn signal circuit are cut, unplugged or missing...

What I believe to be the leads to the left and right signals, respectively. Also, what is the bit of harness splayed out under my hand? It appears to be turn-signal related but I have no clue:


I'm assuming this is where the turn relay/flasher would connect if it were here:


Where the leads emerge from the harness alongside the headlight wiring:


A closer look at the signal relay/flasher connections; according to my diagrams, the White/Green and Grey wires connect to the flasher, but what about the Solid Green wire? My diagram shows a green wire directly beside the flasher unit ending at a connector not connected to anything. Is this green wire intentionally not meant to connect to anything?


So, I have my work ahead of me. How do these turn/taillight connections fit together? Where does my flasher unit fit in? Is there anything else missing that I'm not noticing?

[LukeM]

Welcome to the forum.  Good to see you working on a bit of motorcycle history. :-)  Take your time, get some good documentation, and I'm sure you'll be up and running soon.

This page has a good readout of the DOHC wiring harness.

DOHC wiring harness posting

Doing a topic search on the home page will help you find answers.  I'm pretty confident 99% of people's questions have already been answered (more than once).

Keep us in the loop, and we'll help when we can.
Luke M

[Re-run]

Wow you are actually labeling wires! Lots of people never do that and then hack things up.
Having a shop will be nice if you can access some tools once in a while.

At least the bike does run and is mostly intact. This gives a good base to start with.

[Needforsteve]

Ah yea I forgot to mention, the bike is pretty much complete. I have the tank and seat, they're just off for access.

I'm thinking a new fuse block may be necessary, I ran some wire the other night to test my taillight and discovered a broken taillight fuse connection in the block under the handlebars. Not sure which way I'm going at this point, but I'm investigating a re-wire. My main concern, if I make a new harness, will be ignition. Lights I can wire all day long, but the ignition is what I'm worried about mucking up the most...