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I know this issue has been beaten to death but I have a legitimate question that I have not seen on this forum.

On E-bay, and in other places I am sure, there are temp sensor units for sale. Some screw into a hole somewhere on the motor or I can epoxy one on the radiator, but could I screw one into the radiator drain plug hole. Is there some other place to screw a sensor into that I have missed??? Might have to experiment with the temperature but could that work??? If it works it could simplify the process. How about puting a sensor in one of the radiator hoses at the topof the motor??? I have 2 '78 CX500's to convert to electric fans and I am looking for an easy way out. Simple is good, right???
 

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I think the easiest way would be to epoxy it to the radiator like you said. One that screwed into the drain hole would be cool but kind off odd looking. It is sort of low so it might be out of sight a little.
 

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I epoxied mine to the bottom of the radiator. No Problems.



I believe the bottom is preferred, as the top of the radiator will always be hotter, due to the hot water flowing in from the engine, meaning the fan will not shut off. First time I mounted my sensor I made that mistake. Now it is at the bottom and works great.



Also, use some heat sink thermal paste and sand off the radiator paint where you plan to mount it to get the best connection.



Mike
 

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I looked into using temp sensors made for cars that could be screwed into somewhere but eventually settled on my Top-of-rad position cheap temp sensors.



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=7&t=209



If you want to fill the radiator to the top get an 80 Deg C normally open type.If,like me,you run with the rad level about up to the bottom of the neck a 75 Deg C normally open type will do.



"Shoreride" on this forum may have some 75 deg C ones left if you don't want to have to buy 10,if not I'll send 2 to the US from the UK for $10 inc of postage so you have a spare in case of any mishaps.
 

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You can install a sensor in the radiator plug hole, but you have to make an adapter:



Here is the sensor and adapter plug before installation. The sensor is glued inside.





Here are two variants:





I turned up these on my lathe. The plugs are made of brass, and the threads are 12MM x 1.25. The sensors are available on eBay and are 1/2" diameter.



Michael
 

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I found the 75C switch on the bottom ran the fan too much and put on an 85C switch. To save the battery I used a relay with the coil on a switched feed off the black brake light switch feed, and the power on direct feed from the battery.

Also I had installed an LED charge monitor and found that it was almost always red or yellow. On investigation I found the PO had put in a 90/100W headlight bulb. The fan draws 50W, various tail, running and instrument lights draw another 40-50W. That puts the demand at 170+W


The alternator only puts out 170W @ 5000rpm. An original 55/60W headlamp has solved the problem along with changing to the 85C switch to decrease fan run time.
 

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Joel:

I bought the Gammatronix unit from the UK and mounted it on my Vetter fairing drilling a 14mm (9/16") hole through an existing hole plug on the left side and sealing with RTV. The LED is hard to see in bright light, but is certainly not distracting due to its location near to my left knee. Sorry, no pics. If you really need them I can try to get one later.
 
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