OEM Standard Thermostat Temp Rating?

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Hubbskiboy
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Bike owned: GK76A 1993 and 1990
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OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Sat Jul 28, 2018 9:12 am

Just curious what the standard temp rating for the thermostats on our GK76's should be?
I've looked at all the suppliers of the part 17670-32C20 which I'm positive is the original and none of them specify a temp rating.
I know that most people like to swop it out for a higher temp rated thermostat which also leads me to another question.
How many different thermostats will fit our bike and what temps are they all rated at?
I'm asking because on my bike that actually runs, the fans don't kick in till at least 3/4 of the way up the temp gauge. :?
Which makes me rather nervous every time I do a coolant cycle check.
If anything I'd like the fans to kick in about just after halfway on the gauge.
All the best and hope you're all having a good summer! 8-)
Hubbskiboy.

moforockband
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Re: OEM Standard Thermostat Temp Rating?

Post by moforockband » Sat Jul 28, 2018 11:17 am

85-90C is perfect for old school 4 stroke engines. I bought a heat laser gun from Maplin for £15 which is useful for the garage to check the temp on the rad. There's no need in the UK to run them any hotter. If the bike is fouling plugs, it's because of a problem somewhere else.
The fan shouldn't kick in till just over 100c, so yours sounds OK.
Just done a TD on mine in 28C, and the gauge was nearly on red in the holding area, the fan on mine was running then.

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Sat Jul 28, 2018 11:31 am

Thanks Mofo.
First one to get back to me as per usual. I like it!
What I'll do is remove the Thermostat from both of my bikes and make a note of the temperature spec.
That'll be a good starting point.
The only product photo I can find of this part with the temp spec on is from the cmsnl.com website (see below).
Looks like it should be 82°C as standard, but then again this could be any old image they decided to upload. :roll:

Image

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Sat Jul 28, 2018 11:50 am

Hi Mofo
Another quick question.
Before I start messing around with the coolant sytem again, do you think this disconnected cable (see photo below) would stop the fans from kicking in?
It was like this when I bought the bike and Wullie very kindly pointed out that this cable should be connected to the back of the thermostat housing.
I ran the bike yesterday without the cable connected and I had to switch it off in the end as it got close to the redline.
For your info there are 3 cables all black and white. two of which connect to the two fans as a negative.
Let me know what you think.
Ta,
Hubbskiboy.
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moforockband
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Re: OEM Standard Thermostat Temp Rating?

Post by moforockband » Sat Jul 28, 2018 5:29 pm

82C thermostat sounds bang on.
The black and white wires are all grounds and all need to be connected, and it's very easy to get them in the wrong place. The fan is connected in series with the fan switch (black and blue wire). Make sure the colours match up either side of the connection, as the coloured stripe is really small to see.

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Thu Aug 02, 2018 2:09 pm

OK, here we go again. :roll:
I'm still having the same problem - Radiator fans not kicking in even right up to the temp gauge red line.
Here are the facts.
I know that both the fans work as I've tested them by directly linking them to a 12v battery.
Both of my bikes have 76.5 degree C thermostats fitted.
The one was seriously stuck in it's housing and the rubber was perished, so I've bought another one.
In the meantime, I swopped the one I know that works and kicks in about 3/4 of the way on the temp gauge.
So that can't be the problem.
I've installed a new earth cable from the thermostat housing and checked the circuit, so that's OK.
All the other connections are fine.
I also swopped the water temp sensor from my working bike because I accidentally snapped the male spade connector off the other one.
The only thing left I can think of is the radiator fan switch, but that looks fine from both internal and external side.
Is there any way of overiding this switch, so that I don't have to wait for the bike to get up to operational temp every time I test the system?
I tried touching the two wires together that connect to the switch, but that did nothing.
Any help with this would greatly be apprciated as this is the final hurdle before I can ride the damn thing!
Ta,
Hubbskiboy.

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Thu Aug 02, 2018 2:48 pm

BTW, I don't want anyone thinking that my engine bay is a right mess like in the photo above. ;)
That's what it looked like when I bought the bike! :o
As well as creating a nice new auxiliary fuel tank from a Dual Circuit Brake Fluid Reservoir, I've cleaned up a little bit!

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moforockband
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Re: OEM Standard Thermostat Temp Rating?

Post by moforockband » Thu Aug 02, 2018 3:27 pm

I dont think you have an earth on the radiator fan.

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Thu Aug 02, 2018 3:51 pm

Hi Mofo.
Not sure what you mean.
There are only two wires coming out of each fan.
Positive and negative I assume as they're clearly DC motors.
Should there be another cable?

Hubbskiboy
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Re: OEM Standard Thermostat Temp Rating?

Post by Hubbskiboy » Thu Aug 02, 2018 8:00 pm

Just did a few checks with my multimeter and got some weird results.
All the fuses check out OK including the 10Amp fan fuse.
All 3 negative ground wires (Black and White) from the loom are working correctly, because when I attach the positive connection from each fan directly to the battery the fans kick in.
When I bypass the fan switch and connect my multimeter to the fan connectors I get a reading of 0.5v which very slowly increases.
Without the bypass I get zero volts, so at least something is happening.
As I said, the fans come on if I bypass the whole positive part of the loom so I might just bite the bullet and run a switch directly from the fuse box.
Only problem is if I'm sat in traffic and forget to keep an eye on the temp gauge. :roll:


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