Resistor

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Dode
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Resistor

Post by Dode » Sun Oct 25, 2020 12:27 pm

Hello Folks.
My 350 Saturno temperature gauge has always read high, it gets up to the top of the green area just below the red and stays there, pretty rock steady. The fan doesn't come on, and it is working with new fan switch in the radiator and new temperature switch in the head, so I'm pretty sure it is running at the correct temperature. I read on some old posts about "Luigi" fitting a resistor to the wire going into the temperature gauge, I can't find one on my bike, and I was thinking of fitting one, if only I knew the resistor value? and where it was fitted on the wiring?. It's really just to make me feel more relaxed when I look at the gauge!. I'm hoping it would allow the gauge to read with the needle lower?.
Any comments gratefully received.
Alan.

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Joachim
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Re: Resistor

Post by Joachim » Sun Oct 25, 2020 6:11 pm

have a look at this

http://gileraclub.de/viewtopic.php?f=1&t=8699&p=51175

Maybe you are able to read the color code on the resistor :)

I'm not shure but i remember a thicker resistor somewhere in the instrument box of the Saturno.
But i may be wrong.

ciao Joachim

PS brown/green/black/gold?
That would be 15Ohm 5% The size might be about 0,25W If you can get something with higher wattage no problem.
But take care you can still mount it

Or is there a yellow ring to see between green and black?
As far as i know the 5% tolerated resistors did have only 4 rings not 5, so...

Another solution, take a potentiometer than you can adjust the temperature you want to see :)
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Dode
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Re: Resistor

Post by Dode » Sun Oct 25, 2020 9:15 pm

Hi Joachim,
Once again to the rescue, thank you.
Mine is in fact an early model, and doesn't seem to have a resistor.
Of course, it's only to make me feel better when I look at the gauge!.
Alan.

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Joachim
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Re: Resistor

Post by Joachim » Mon Oct 26, 2020 6:48 am

looks like the pic is from an RC not from a Saturno.
So maybe there is another resistor value needed.
I will see if i can check this next weekend at home.

ciao Joachim
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Carsten
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Re: Resistor

Post by Carsten » Mon Oct 26, 2020 6:37 pm

Hi Alan,

just replaced the resistor in my Saturno 500. I can confim the 15 OHM, 0.25 Watt mentioned by Joachim.
Don't forget to protect the resistor and the cable with a silicon tube. It gets quite warm next to the cylinderhead.
Actualy my solder connection was broken.

All the best

Carsten
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Joachim
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Re: Resistor

Post by Joachim » Mon Oct 26, 2020 7:18 pm

rulez

But why did i have this pic in my head, showing a resistor inside the instrument panel :)
I suppose i will have to check

ciao Joachim
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Dode
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Re: Resistor

Post by Dode » Mon Oct 26, 2020 7:35 pm

Excellent, thanks folks.
I too was looking for the resistor up by the gauge. I'll pull the tank off and check.
Thanks,
Alan.

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Joachim
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Re: Resistor

Post by Joachim » Sun Nov 01, 2020 9:44 am

the resistor inside the gauge seems to be on the Nordies :)
The Saturno panel is not design for an easy repair.
I just had a look....
So i could never have seen it there ;)
As i have repaired some Nordie speedos i must must have it seen there
Sorry for the confusion i have caused....

ciao Joachim
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Dode
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Re: Resistor

Post by Dode » Mon Nov 02, 2020 8:58 pm

No confusion Joachim, just help, thanks.
There was in fact no resistor fitted, so I've soldered one into position. I haven't had a chance to ride and test yet, maybe tomorrow. Our roads are very treacherous with wet leaves, you have to be careful. I had it idling outside for a short while and observed the needle moving so something must be working!
Alan.

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Re: Resistor

Post by Dode » Sat Nov 07, 2020 3:29 pm

The resistor works!, the gauge reads slightly above the space between the two green parts. I know of course the bike is running at the same temperature, but somehow it makes me relax a little more knowing the gauge is reading correctly.
Thanks to all.
Alan.

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Joachim
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Re: Resistor

Post by Joachim » Sat Nov 07, 2020 3:42 pm

*thumb*

ciao Joachim
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500IOM
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Re: Resistor

Post by 500IOM » Wed Dec 30, 2020 5:10 am

Great post Alan, I am having exactly the same behaviour on my 500 IOM, the temperature gauge goes to just below the red zone and stays there, no matter what.

The only difference is that it's initially good, say for the first half hour or so of riding, at no more than just above mid zone in the green range, then goes to near the red and stays there.

I checked the pump, fan switch, fan, all good. I then checked the water temp with a calibrated thermocouple at the radiator near the filler cap, and found that it's around 90-92C with the gauge near the red. With the engine idling in a warm garage, the fan would pull it back from >90C to around 80C in 5 minutes or so, but the gauge was still near the red and hardly moved.

A faulty resistor sounds like a possible reason for this behaviour, I will check it! Maybe it's initially OK from a cold start, and then as the engine warms, it goes short circuit or something like that.

Cheers, Lex

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Joachim
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Re: Resistor

Post by Joachim » Wed Dec 30, 2020 10:09 am

maybe the sensor in the cylinder head itself has a problem.
I had this on my Nordie years ago.
Replaced it with something from a Piaggio scooter and everything was ok.
I suppose Luigi has used the same sensor in all the 4strokers
I will see if i can find the details. There should be an old article around here in the german section

ciao Joachim

PS

viewtopic.php?f=1&t=7719&p=43038
Gilera Runner not Piaggio :)

Luca found this replacement FACET 73073
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