75 GT550 M Wiring Plug Question

[Syd]

IMG_2667.JPG

Can some one help me with the following - I am working to finish my 75 GT550 M restoration and when working on the wiring today, I noticed the following;

Behind the side cover, the male plug which is for the alternator has 3 x yellow wires, 1 x green and 1 x black/white wire as shown on the attached photo of the plug. The female plug in the panel has the same 3 x yellow wires and 1 x green wire, however there is no black/white wire to match up with the black/white wire on the male plug. There is also a blue wire in the female plug which also does not match up with the male plug - big puzzle? I have checked my wiring diaphragm, however its very poor and not in colour. Is this wiring plug set up for my model GT550 M all correct? Maybe its a wiring thing between using a standard GT550 wiring harness and different model specs for different markets? If anyone can help, that would be much appreciated.

[GTandcbr]

https://www.google.fr/search?q=suzuki+g ... iPMHSokI2M" onclick="window.open(this.href);return false;:
Does this help?

[tz375]

Black with white trace is ground/earth and blue is to the neutral switch.

I suspect that the two harness parts are from different years. Does yours have a neutral switch and if so where does that blue wire go? It is probably in the gear indicator harness.
If so, trace that blue in your harness forwards and see where it connects.

It appears that the Black/white wire may have been deleted in later models. You should be able to insert a terminal and lead and connect that to a suitable chassis ground.

[Syd]

Thanks guys for the handy link to the colour wiring diaphragm which is very helpful. Thanks also for the comments about the black/white and blue wire for the neutral switch. I have never had the bike going, therefore I don't know if the neutral works as I stripped the bike down as soon as it arrived. The restoration is all coming together fine, so I'll check out the blue wiring path from the gear indicator switch as suggested and also from the gauges to see what is going on - all a bit strange as everything looked 100% original

[Evans Ward]

^ Looking fantastic!!

[jabcb]

Is that the bike that I sold?

[Syd]

Yep, that's the one..

[tz375]

Just a thought. It is possible that Suzuki changed the design to no longer use the Black/white and blue leads from that connector pair and that those leads are redundant. You will know when you manage to check the gear indicator switch and indicator itself.

I would still connect the ground (earth) lead just to be sure the alternator is fully grounded.

[jabcb]

Oregon Motorcycle Parts sell new replacement rectifiers for reasonable $$$.
This is what they say about the stock Suzuki triple rectifier: “The later GT750 and perhaps the smaller bikes in the GT series had only 4 wires in the plug. Some bean counter at Suzuki must have figured that since the rectifier grounds through the mounting post, a ground wire was not needed. This rectifier also grounds through the mounting post but I include the redundant ground wire. Do not worry the original rectifier on your GT only had 4 wires, this one will work on your bike.

The good news is the rest of the wires are in the same place and in the same plug.”

http://www.oregonmotorcycleparts.com/rectifiers3p.html

[Syd]

Thanks for the information about this - I traced the wiring back from the gear selector switch and all the colours match up, however the blue wire separates from the harness just before the plug and connects to another blue wire which runs in another branch of the main harness to the head light, therefore this all looks in order. The black/white wire is earthed to the alternator housing that goes to the plug - there would no problem to make up a ground wire on the other side of the plug.

[MikeH1A]

Syd,

Nice to hear from you again. Another lovely job heading towards completion. You're getting a pretty smart looking stable organized !

I heard a rumour you had been elected the President of your local classic bike group - are congratulations in order?