Wanted: GT750 water temperature sensor

[Madbuffalo]

Let me know if you have a usable one you'd be willing to part with. I installed the '72 fan system on my '75 years ago but have never had a working temp sensor.

Suzuki part number 17680-31010. Discontinued according to Alphasports. Reiner's list shows he has one but the price is a little steep for me.

The one I have has a flat male connector. There's one on ebay but it appears to have a round connector.?

Thanks guys,
Josh

[oldjapanesebikes]

There's one on ebay but it appears to have a round connector.?

Listing 380335069049 ? That one is for the temperature gauge. And do you have the relay ? There is a listing for those at 200947790073. And my apologies, but I don't have any spares, otherwise you'd be welcome to it.

[Madbuffalo]

Yes, that's the listing. Do you know the part# for the sensor I need? I do have the relay and other components and if I unplug the sensor everything works as it should. I've been slow to finish this project because to be honest it's hardly ever needed to come on to cool the bike. The temp has gotten a little warm a few times in stop-and-go traffic though so I'd like to get it sorted out. Even with the chambers jetted correctly they seem to run a little hotter than with stock pipes.

[oldjapanesebikes]

You have the right part number - 17680-31010 is the fan sensor, and 34850-65011 is for the temperature gauge. Take a look at this listing:

http://www.eparts.us/270664,auction_id,auction_details" onclick="window.open(this.href);return false;

And you do have the right thermostat housing with both threaded sensor holes available ? There were three different ones, and the later housings don't have the hole drilled for the fan sensor, just for the gauge sensor. The 'M' and early 'A' style had a bull plug in the fan sensor hole above the gauge sensor hole.

[Madbuffalo]

You found one! Do you know how that site works? If I can just call/email to buy it that's great but if I need to wait 125 days for the auction to end I might look elsewhere.

Yes I took the correct thermostat cover and sensor from a '72 when installing everything a few years back, it's just that the sensor has never worked and I haven't gotten around to replacing it. It has been sort of a low priority since the bike rarely gets hot anyway. My 60639 engine had the plug and my 66570 engine has no hole drilled so the changeover appears to have happened sometime during the '75 model year production.

Just to be sure, If I unplug that sensor and the fan turns on then the sensor is bad? I want to be certain the relay isn't a possible culprit before going ahead with a new/used sensor.

Thanks Ian,
Josh

[oldjapanesebikes]

You found one! Do you know how that site works? If I can just call/email to buy it that's great but if I need to wait 125 days for the auction to end I might look elsewhere.

eParts is an odd web site, but you do often find things there for decent prices. The listing company is Sirius so you could try emailing them at sci@siriusconinc.com and ask for the price with delivery. SCI used to accept phone orders, but have moved to a full on-line setup. When it works, its great, and when it doesn't they lose business. Their issue I suppose.

If I unplug that sensor and the fan turns on then the sensor is bad?

Actually - it was designed to fail safe, so an open circuit turns the fan on - and when the relay under the tank is grounded via the sensor, the fan is off. The sensor when cold goes to ground, and when hot goes open circuit. That's why, when everything is connected with the engine cold and you turn the ignition on, the fan kicks just for s split second and then stops as there is a very short delay as the relay pulls in. Getting the fan to actually turn on when the bike is moving is not easy unless the ambient temperature is really damned hot or something is wrong. I have been able to get it to kick in when the engine has been idling a while - a long while. The temp gauge was getting close to 90% indication.

I suspect your existing sensor is likely fine. You might be able to test the sensor by putting it in boiling water with the brown lead from the relay to the centre connection, and the sensor housing connected to ground (so suspend the connections above the water somehow with just the end immersed) . With the ignition on and the sensor hot enough, the relay should open and the fan should kick in.

[Madbuffalo]

You might be able to test the sensor by putting it in boiling water with the brown lead from the relay to the centre connection, and the sensor housing connected to ground (so suspend the connections above the water somehow with just the end immersed)

I just tried that except used my multimeter. With leads attached I held the sensor half submerged in boiling water with channel locks. No matter how hot the water got the meter would not read above .8ohms resistance so I suspect the sensor is bad, but please confirm you agree.

[oldjapanesebikes]

A hot air gun would likely damage the insulation so I'd hesitate to suggest trying it, but more heat would be nice if it were possible just to be certain - however, I'm inclined to agree it doesn't look as if it is working. These things are pretty simple and also pretty rugged, but obviously were available as spares for a reason If you are not in a hurry I could do some tests with one of mine just to see what readings I get for comparison purposes - I'd need about 2 weeks as I'm just heading out of town for a week.

[Madbuffalo]

With map gas i was able to watch the resistance climb to about 120ohms then slowly fall to 0.5ohms once I pulled the torch away. Still, It seems like the meter should be going to infinity when the circuit is open..?

I really appreciate the offer to do some investigating for me but I have a trip planned with my dad in a few weeks so by the time you get back to test it will likely be too late if it does come to ordering a new sensor. I'll hunt around a few days for a used one before contacting siriuscon for their NOS one. Sounds like the used ones don't go bad very often anyway.

[Madbuffalo]

If somebody wants to move this thread to repair it's purpose has really changed since starting out so that would be fine with me.

I ended up wiring an on/off toggle switch to run the cooling fan. I decided on the manual switch because, to me, it seems more proactive. If I'm in a situation where the bike might get warm I can flip the switch before it ever happens. I had been hesitant to do it because it isn't 'correct' but really the fan was never correct for the M anyway. Plus the mod can always be reversed in the future.

I put the switch where the 'S' is usually found.


It's wired to connectors for easy removal of the cluster if needed. From there two wires are shrink wrapped together and follow the normal harness routing back toward the relay.


One wire goes into the sensor connector and the other (just right) is grounded at the relay.


It's been working well so far and has already helped me out in a bad traffic jam the other day.

[oldjapanesebikes]

Finally had a chance to test a known good fan temperature sensor, and it does show a short to ground normally, and then open circuit when heated. I used a hot air gun and on cool down it flips to short, so nothing in between - its either open or closed.

Sorry for the delay in getting back - couldn't find it.

[Madbuffalo]

Thanks Ian. Hope you enjoyed your time away.