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Alternative fan thermoswitch
Here in New Zealand the local Honda dealer wanted 325 nzdollars for a fan switch. No way was I going to pay that, so I started looking for alternatives at my work, in our Tridon catalogue. I found one that turned on at 95 degrees, off at 90 degrees and had a 14 by 1.5mm thread. I then turned the hex off the old switch in our workshop lathe, removed the guts of the switch, bored it to 12.5mm and cut a 14 x1.5 thread. With this piece fitted to the housing the new switch fits like a dream,I only had to change the terminals on the wiring loom to spade type. It all works a treat, turns on a little sooner than before, but I don't think that matters too much. The Tridon part number is TFS064 if that is any help to you guys, and the total cost of the exercise was less than thirty dollars

Ian in Auckland, New Zealand 76gl1000
#1 01-15-2009, 02:33 AM,
Welcome to the site, Ian. Good information.
Remember, it's the journey, not the destination, that matters.
#2 01-15-2009, 08:25 AM,
For those without equipment to make the above mod, here's an alternitive...
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I got one of the "upgraded" type that turns on at lower temp than the stock one...
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It does work quite well but you will notice the charging strain it can cause at idle speed... Now my temp gauge never gets above midway...
Ed Zogg
#3 01-15-2009, 09:45 AM,
Welcome to the site Ian! I guess you and Keener must be related since you have the same name :lol:
I don't know what price they wanted for the thermostatic switch in New Zealand, but here they're $61 and change from Honda. It's nice to know there is an alternative.
Along the same line, though, using a fan switch as EdZ described can have unintended consequenses. Putting a switch with lower set temperatures can have adverse affects on the cooling fan. The fan runs longer, which will shorten it's life. Running the fan while driving at "freeway" speeds overspeeds the fan motor and can cause bearing damage. And as EdZ pointed out, more load on an already overworked charging system.
The thermostat controls engine temperature. For those of you that think it needs to run cooler, I'd suggest a lower setting thermostat (or fix the problem that's causing it to run hot).
The cooling fan is an overheat "protection" for extended idling and extreme conditions. Burn out a fan motor, now you have no protection at all.
#4 01-15-2009, 08:40 PM,
In theory what GL states is true... How ever, I have not heard the fan come on even running at around town speeds let alone on the highway... The other issue is the fan most likely is spinning while on the highway just from the wind blowing through the radiator (kinda like a pinwheel effect)...
He is correct in that the thermostat is what controls engine temp, but when the thermonstat is already wide open how can it lower engine temp... It is known that using an after market thermostat reduces coolant flow a little bit and this has caused several folks issues... I got to believe the stock thermostat often times is also wide open... What this new fan switch does is to insure the coolant in the radiator is not already to hot...
What I have noticed since using the new switch is that the thermostat finally can do it's job much better... My temp gauge now gets up to 3 bars and stays there... With the stock switch it used to go to 5 or 6 bars and then the fan would come on and bring it back to normal (3 bars)...
At highway speeds it used to stay at 3 bars all the time, now it does the same even driving around town...
As for the charging issue, it only shows up at idle speed... Once it gets to around 1500 RPM it too goes back to normal... This too helps with yet another heat issue, that being the regulator temp (dumping excess power to ground)... Thus far I have not run into any issues with battery charging nor any with the fan coming on more often... I have noticed even though the fan comes on more often than before, it runs for a much shorter time before turning back off...
Ed Zogg
#5 01-16-2009, 10:06 AM,
Ed Z Wrote:In theory what GL states is true... How ever, I have not heard the fan come on even running at around town speeds let alone on the highway... The other issue is the fan most likely is spinning while on the highway just from the wind blowing through the radiator (kinda like a pinwheel effect)...
Ed isn't theory, it's physics. The thermostats are set to maintain @185 F operating temp. If your cooling fan is coming on at 177, the engine never really reaches operating temperature, except in the most extreme cases. The thermostat isn't wide open all the time, it cycles to maintain 185. Without air flow through the radiator, it will go wide open in an attempt to correct engine temperature. The pinwheel effect is exactly the condition that causes the damage. It causes the fan motor to overspeed.
If your thermostat is set at 185, and the cooling fan turns on at 177, the thermostat never gets a chance to do it's job. If you don't hear your fan running at freeway speeds, join the club, I don't either. But at 177 start up temperature, it pretty much would have to be, wouldn't it? Unless you have a 165 t-stat installed.
Running three bars instead of five may look better on your display, but you're not doing yourself any favors.
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This isn't supposition, or speculation. This is information passed along to me by a thirty year Honda Motorcycle tech/owner/dealer who warned me against lower thermostatic switches. I took his advise.
#6 01-16-2009, 01:35 PM,
The fan switch cannot cure an engine which is suffering from coolant circuit troubles. The cooling system has to be ok, that means no deposits must reduce the thermical flow from engine parts to fluid and from fluid to air. The thermostat must be 100% ok, if it doesn't open or close completely (or at wrong temperatures), it will always be the cause for excessive engine wear or overheating.
If the cooling system is healthy, a "cooler" fan switch will NOT lower the operating temperature. Why? If it tries to, the thermostat will reduce the flow of coolant to the radiator. The only effect if You choose a switch which turns on at lower temperature than the thermostat is: The fan will run all the time.
If You happen to have a Goldwing which tends to overheat with the stock temp switch, and which does no longer overheat with a "low-temp" fan switch, this indicates Your cooling system is not healthy and/or the thermostat is bad. The fan switch kind of makes the job of the thermostat then.
You are curing the symptom, not the cause.
Remember: The fan is a feature that is designed to switch on in case of emergency ONLY!
Normally the wind should take the heat from the radiator. My wing fan never turns on but on hottest days in stop-and-go jams.
Do not be afraid when the temp gauge goes up to the red mark occasionally. As long as it does not pass it everything is just fine.

#7 01-17-2009, 04:57 AM,
I concur with Ray for the most part... My fan does not come on "all the time"... It does not come on unless I'm sitting in traffic on a hot day... I also agree that the temp gauge running up to the high end will not likely cause engine damage either... How ever it (heat) is one of the causes of oil break down... I did not have any over heating issues prior to changing to the new fan switch either... All I can offer up here is that by monitoring using the new style switch the engine temp is far more stable than before (temp gauge shows 3 bars regardless of weather or driving conditions)...
I really did not want to step on anyones toes here, just passing on my testing data...
As to the 30 year honda tech qualifications goes, I can only offer up years of college in thermal dynamics and heat exchanger design....
Ed Zogg
#8 01-17-2009, 11:25 AM,
Ed, this was no attack...I truly apologize if it reads that way.
The effect You describe, that the fan doesn't run always and the temp gauge is more stable now, this indicates for me a slight malfunction of Your thermostat.
Does the engine warm up quickly, even on a cold day?
On the other hand, replacing the thermostat is more work than replacing the switch. If You have good results, why not?
#9 01-18-2009, 10:37 AM,
First of all I feel I owe this site an appology... As I reread my post, I did come across a bit on the defence side...
In answer to your question, no it doesn't warm up quickly... She's always been cold blooded and taking several miles to get fully warmed up (3 bars)... What has happend is the fan just turns on earlier (when just sitting in traffic) than it did before... With the Honda switch I would watch the temp gauge climb up to 6 bars before the fan would come on... Then after the fan ran for awhile the temp would return to 3-4 bars and the fan would shut off... Now the fan starts just as the temp gauge is about to hit 4 bars (once in a great while it will) and then the fan comes on... It runs for a much shorter time than it used to with the honda switch before it turns off again...
If I were to see my cars temp gauge climb when sitting in traffic, I would be very concerned about an impending over heat condition... But as is with my car, the temp gauge just climbs to the normal area (midway on the gauge) and never moves from that point... I consider that a good working heat exchanger (maintaining a constant engine temp)... Now, with the new switch, my bike also has a very stable engine temp...
Ed Zogg
#10 01-19-2009, 07:33 AM,
Quote:But as is with my car, the temp gauge just climbs to the normal area (midway on the gauge) and never moves from that point

You are right, that is exactly how it should be. My VW climbs to 90°C/194°F within a mile or so and then it is fully stable. In stop and go traffic, it climbs to 95°C/205°F until the fan switches on.

My wing warms up very quickly, about one mile and it is in operating range.
The temperature is not so 100% constant as in my car, possibly because the radiator is much smaller. But it is usually only slightly off the middle.
I have a manual fan switch on my GL1100, I switch it on when there are very hot conditions in town.
Works ok for me.
I have a Ford Escort or Sierra fan switch in my GL1000, but I could get crazy, I lost the part# of this item. Quite a lot of people have asked me already. Was around 8Euros some years ago and is a direct replace.
#11 01-19-2009, 09:27 AM,
After reading the replies I had another look in the Tridon catalogue and have now fitted a switch that turns on at 100degC and off at 95degC, the fan certainly does not run for as long as with the 95degC switch, I am going to stay with the hotter one.

Ian in Auckland 76gl000
#12 01-20-2009, 01:16 AM,
Interesting conversation here. Just want to add that the best thing you can do for your engine is to get it up to full operating temperature as soon as possible after startup. Keep it there or a few degrees hotter all the time it is running for best engine life and performance. This did not happen in this thread, but I cringe when I hear about guys who remove the thermostat from their engine with the explanation that a cooler running engine will last longer, this is not the case at all. An engine running at its designed operating temperature will always give you best performance and long life because the metals within the engine expand and conform to their engineered operating specifications and tolerances and the oil is at the correct temperature to best do its lubricating job. This why cold starts and pushing a cold engine can be so detrimental to the life of your engine. So, in a nutshell, get your engine up to full operating temperature gently and keep it operating at its designed operating temperature while you're riding and you will be adding many miles to the life of your engine plus you'll get better economy regarding fuel, oil and maintenance costs.
Ed (Vic) Belanger - 1954-2015
Founder of

#13 01-29-2009, 10:01 AM,
I concur 100% with Vic...
Ed Zogg
#14 01-30-2009, 09:37 AM,
I guess I am too cheap to buy a fan switch, as I just unplugged it, went to Radio Shack and bought a toggle switch, and mounted that on the lower right side of my Vetter Fairing, and ran a couple of wires to the plug for the fan switch. If My engine temp gets too hot, I can just switch on the fan manually, and bring it back within limits. I haven't had any overheat problems at highway speeds, and very few times I have had to use it around town except when Idling for extended periods.
Is that bad :?:
#15 01-30-2009, 07:36 PM,

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