86 gsxr harness help

[v-twinwalker]

hey everyone, have an 86 gsxr 750 with a b12 motor in it and a 2001 gsxr 1000 front and rear end on it.

anyways, i removed the wiring harness that was on the bike because they had fitted a k series gsxr gauge cluster and hardwired everything and taped over it, and had a bunch of random switches for something i couldn't figure out, and three switches to start the bike, it was ridiculous. Looking back I probably wouldn't have done that but it was atrocious.

I do have for the most part an uncut 86 gsxr 750 harness and i understand a good bit of where the connections go but i am having trouble with a good bit of them as well, primarily the ones that go to the rear of the bike and also the middle. 

What I am wondering is if somebody has a diagram of an actual 86 gsxr harness pointing to all the connections and labeling them as to where they go, instead of just one you would find in a service manual.

If there is a chance somebody wouldn't mind doing this for me or maybe just listing off the connections under a photo of a physical harness, it would be seriously appreciated.

 

Just to give a bit of background, I'm 26 now and the 1986 gsxr 750 was my first real dream bike when i discovered it probably when I was 20, at the time i was riding a 1982 gs650gl and quite literally rebuilt the whole bike from ground up. I now currently ride a 2001 zx7r that I've done a bit of work on to fit a zx10r front and rear end on, while I love this bike and don't plan on selling it I still seriously want to experience riding a first generation gsxr just to see what it's about, my worry is that if I sell this bike as a project I may never get to ride a slabside and I would regret it as long as I live (also i'd lose out on plenty of money if i didn't end up keeping it lol).

[Dezza]

The wiring diagrams in the genuine Suzuki manuals are about as good as it gets. These manuals are freely available as pdfs online. Alternatively I can email you a copy. What market bikes are we talking about here? I ask as the looms vary according to market but the diagrams are all provided in the Suzuki manual. e.g. I think the parking light switch wiring differs between UK and USA models.

From experience it shouldn't be too difficult using an OEM slabby loom for a 7/12. It will make things a lot easier if you were to source an 1100 slabby cdi unit and ignition trigger wheel and pick-up because then you won't have to modify the loom very much if at all. The slabby CDI won't work with the b12 pick-up and the B12 CDI takes completely different connectors to the slabby. An 1100 slabby ignition works well with a b12 engine. I don't know about a 750 ignition but I guess the timing may differ (the 1100 is a little advanced low down compared to the B12 and perks the engine up a bit).

When using looms from an unknown source I find it helps to first remove all the tape and to clean the glue off the wires with white spirit, then shove the lot in a suitable bag and into the washing machine. You can then inspect the loom and see what connectors and wires need to be replaced. Japanese connector blocks, wire and crimpers are not expensive and freely available. Get all the electrics working before re-wrapping the loom with the correct loom tape, not insulation tape (hold it together in the mean time by small cable ties).

Edited December 30, 2025 by Dezza