Sundial Moto Sports

Hello everyone,

This is my first post on this forum so be kind. I have done a lot of work on Suzuki GS models, basically 1978 through 1983, but I recently picked up my first 2 stroke. A 1974 GT750. So several things are much different on this bike than I'm used to. It's in really good shape and my progress to get it running again has been going very well. But I've hit a snag in regards to the headlight wiring. This is going to take some explaining to please bare with me.

The bike, when I first got it, had a fairing on the front that was wired up in an odd patch work way, which included 18 feet of stereo wire. There was no headlight on it at all. I have since gotten a complete headlight for it and started getting the wiring set back to the correct stock configuration. Except...the turn signals. The right side works just fine but the left side, only the back one comes on and stays on, and the front doesn't even come on.

So, following other peoples posting on this site, I cleaned up the ground wires on the turn signal itself as well as the turn signal relay. No change. I then replaced the bulb with a known working one, and no change. I then hooked up a complete extra turn signal unit, and again, no change.

So I naturally am assuming there's a ground wire issue somewhere. HOWEVER, on all the wiring diagrams I can find, it shows ground wires as black/white in color. I have NO black/white wires in the headlight area. BUT, I do have a lot of brown/white wires. I started guessing...maybe my ground wires are brown/white and not black/white?? Wiring diagrams also show some ground wires being grounded to the headlight housing. I don't see any wires hanging in the headlight area that can be grounded to the headlight?

BUT..I do have a cut brown/white wire hanging that doesn't have any other brown/white wire to match it up to. So, I thought ,maybe this is the missing ground wire issue. So I hooked it up as an acting ground wire and got no change in results. The rear left turn signal stays on and the front does nothing.

I've been told that if the turn signal relay works for one side, it should still be a good relay and that's not the problem.

I hope this isn't too confusing to everyone. I'm sure it's a simple fix. Maybe my confusion with the colors of the wires is muddling my mind. And I'm thinking maybe the grounding of wires to the headlight housing is only for the older 72 and 73 model years?

Any help is appreciated. Thanks

Take the wire from the working front indicator and substitute the wire from the one that doesn't flash. Does it now work?
You should have a rear flashing and the opposite side front. If not then it's a problem with that indicator, if it does then it's probably the double connector in the headlamp.
You can put the wire from the non flashing indicator to the orange wire to test it (ignition on) - it should stay on, again if it doesn't the fault is in the indicator - either wiring, bulb holder, bulb or earth. If one side works it shouldn't be the earth. Is it the correct bulb? Check the connections underneath - single contact - clean it and swap bulbs from one side to the other.
The flasher relay needs two bulbs to be able to flash. It works on current flow, which is why LED bulbs don't work unless they have a resistor in them, which makes them a waste of time if you are trying to save power.
Let us know how you get on.

Ok what you have is one for the bikes with the oddball wiring colour harnesses that happened for a short time during 74 model manufacture. It appears the stock black/white wires are now brown/white in your harness from looking at the photos.
For the ground in the headlight there was once a four barrel female bullet fitting on a black/white ground wire, yours may have been cut off where the bare end on the brown/white is showing.
To confirm this is your ground simply remove the battery ground wire and check for continuity from it to one of the brown/white wires.
You can also remove the fuel tank and look at the ground wire/eyelet about midways under the tank on the frame backbone, what colour wire is coming from that eyelet, is it brown/white??
To check that non functioning indicator turn the circuit on and apply a ground wire to the threaded or shaft part part and onto a place such as the engine itself or battery ground.
As long as the unit has a good bulb it should complete the left indicator circuit and start both blinking. Make sure the battery is charged fully as sometimes one side can be a bit slow to respond if voltage is slightly low.
Those harnesses are annoying to work with since the colours don't relate to the true standard colours and to make it worse they are not fixed.
By that I mean the ground on your harness might be brown/white while on another oddball 74 harness it might be green/yellow. By now the little identifier tags have long dropped off, which makes it worse.

_________________
Two strokes, its just that simple.

The list:
69 Suzuki U70
69 Suzuki T500
72 Suzuki GT750 cafe
74 Suzuki GTXVR project
75 Suzuki RE5
75 Suzuki GT750
76 Suzuki GT750
81 Suzuki GSX1100
86 Suzuki RG500
88 Honda CR500
93 Honda CBR900RR
98 Suzuki GSF1200 X 3

Thanks for the quick replies! Especially in regards to the wire colors. I will do as you both say and report back later.

I'm right in the middle of carb rebuilding and boy is that a mess! Probably the worst I've ever seen and this is my 8th set of carb rebuilds.

Again, thanks and I will post my results.

Carb rebuilding requires an ultrasonic cleaner, especially for those BS40s you are working on which have a myriad of extra passages normal carbs dont possess.
Every set I've seen or had the pleasure of working on has been botched in some form or another by previous owners. Its seems yours follow these basic rules.

_________________
Two strokes, its just that simple.

The list:
69 Suzuki U70
69 Suzuki T500
72 Suzuki GT750 cafe
74 Suzuki GTXVR project
75 Suzuki RE5
75 Suzuki GT750
76 Suzuki GT750
81 Suzuki GSX1100
86 Suzuki RG500
88 Honda CR500
93 Honda CBR900RR
98 Suzuki GSF1200 X 3

Ok, I finally got those right turn signals to work. It ended up being a grounding issue. When I hooked up a separate wire to a ground on the bike frame and them to the turn signal threaded stalked, as was proposed, it worked. I then hooked up the separate wire again from the stalk to the open brown/white wire. The one I mentioned before that I thought was a ground wire. It worked again.

So my thought now, is that the open brown/white wire in question was pulled from one of the connectors that have a bunch of brown/white wires coming out of it. There is one close by and looks as if it should reach and fit in there. You can see what I'm talking about in the picture.

However, I was wondering. Rather than opening up one of those connectors, which looks like it would be a lot of trouble to put back together, if I could just hook up a wire to the brown/white ground and hook that to an eyelet and bolt the eyelet to the turn signal stalk? Would this be a quick solution? Or am I missing something?

At least I'm finally on the right path!

Thanks, Bill

Plastic (coated) to power, ground to brass.
Get it wrong, you're on your a$$.

We spell it different, but the idea is the same.

Dont open one of those bundle pinch terminals on the ground wire as they are a one shot deal. Since theres a short brown/white pigtail wire coming out of it, splice a black piece onto it with a double female bullet terminal at its end.
Make a pair of indicator grounds about six inches long, an eyelet around the indicator stalk and a male bullet at the other end.
Now you can plug the two front indicators into this specific socket you made on the harness.
This is only a suggestion but its what I'd do in your case.

_________________
Two strokes, its just that simple.

The list:
69 Suzuki U70
69 Suzuki T500
72 Suzuki GT750 cafe
74 Suzuki GTXVR project
75 Suzuki RE5
75 Suzuki GT750
76 Suzuki GT750
81 Suzuki GSX1100
86 Suzuki RG500
88 Honda CR500
93 Honda CBR900RR
98 Suzuki GSF1200 X 3

Thanks for all the help. I believe I'll do the double ground set up to the turn signal stalks.

And as for the carb rebuilds and cleaning. I think I'll be heading out to get an ultrasonic cleaner. I know from my research and from others that the carb bowls on these things take due diligence.

Thanks again for everyone's help.

Harbor Freight have a very useful unit, the only thing is you have to take the carbs off the rack to fit each one in.
It has a timer and heater with a stainless steel bowl.

http://www.harborfreight.com/25-liter-u ... 95563.html

_________________
Two strokes, its just that simple.

The list:
69 Suzuki U70
69 Suzuki T500
72 Suzuki GT750 cafe
74 Suzuki GTXVR project
75 Suzuki RE5
75 Suzuki GT750
76 Suzuki GT750
81 Suzuki GSX1100
86 Suzuki RG500
88 Honda CR500
93 Honda CBR900RR
98 Suzuki GSF1200 X 3