Fan Thermo Switch Repair

[pjgoeman]

I’m in the middle of trying the fan Thermo switch repair as described in the Shop Talk section and I’m just curious about how the switch works. My fan would not come on and when I disassembled the switch the pin was stuck, although it didn’t take much persuasion to get it loose and out.

What is the function of the pin? How does the switch close the circuit to switch on the fan? Just trying to understand how it works while I soak the parts in vinegar.

Thanks.

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[Whiskerfish]

I have never done this and unfortunately the OP has not logged on in over a year. My Guess is the pin is a differential metal and expands to make electrical contact at a specific temp, But that is only a guess.

[Rat]

Did a couple years ago, worked fine .... but don’t remember the details .... just followed the instructions

Gord

[pjgoeman]

Well, the fix didn’t work for me, on to some other solution.

[Don R]

The cx500 switch doesn't fit, despite info to the contrary. I ended up buying a new replacement from ebay. It's fine so far and I didn't need to change the wire ends.

[Sidecar Bob]

The CX/GL500/650 family use a switch that has 16mm threads. The GL1000/1100/1200 one has 18mm threads.

FWIW, I installed a new fan switch with 18mm threads made for a Suzuki when I installed the "new" engine a couple of years ago and quickly realized that the one I bought turned on at 82c instead of 92c so the fan came on about the time the engine warmed up and stayed on until I parked it. Last spring I replaced that with the one that was in the old engine and it failed in the fall. Fortunately I have a switch to the instrument panel so I just turned it on every time I drove for the last few weeks and I ordered one on eBay over the winter.
When it arrived I checked it and discovered that they had sent me the 16mm version so I contacted the seller and they sent me the proper replacement with the usual "Sorry. Please keep the incorrect one." so I now have a spare for my winter machine too.
I've installed it but I haven't started the engine with it yet (still waiting for the new front tire & tube to arrive).
I would post a link to the one I bought but the seller's eBay store currently has no items listed. I suspect this is because the shipping company they use is not accepting items for overseas delivery at this time.

[pjgoeman]

I ended up buying one of the $15 switches on eBay vs. the $60 K+L made in Japan switch. My budget is tight so I’ll take a chance on the cheap one. It should be here midweek, I’ll give it a try and report back on how it works.

[pjgoeman]

My $15 eBay switch showed up and the thread diameter is smaller than the OEM switch. The eBay seller refunded the money and told me to just keep it.

Not sure what to do next. The bike doesn’t overheat while I’m riding and I made up a little jumper wire to put in the plug if I let it idle in the driveway while syncing carbs or whatever. Maybe I’ll try one of the $60 K and L switches that are also on eBay.

[Sidecar Bob]

They wouldn't send you the correct replacement?

There must be an automotive one that fits if we could find it. The one with 16mm threads fits some Honda cars as well as the CX/GL500/650 family...

[Track T 2411]

Part way down in this thread, Hott recommends a switch from an automotive application. Much less expensive than OEM, but better quality than some you'll find on Ebay. I installed one in my 1100 (with the recommended relay) and have had no issues. It does require getting rid of the boot and using blade type terminals...
viewtopic.php?f=13&t=60983

[Sidecar Bob]

The 16mm thread automotive one is exactly the same as the one that came in my 650 and it doesn't require a relay.

[Track T 2411]

A relay isn't required, just 'good practice' on a switched circuit to prolong the life of the switch...

[ob1quixote]

My switch lasted 41 years.

[Sidecar Bob]

I have a feeling it is the number of cycles that eventually kills these switches, not anything like contact arcing due to load.

[pjgoeman]

Well, it’s been almost a month since I worked on this due to other priorities but I’m back at it. I went ahead and ordered a thermal fan switch on eBay that was identified as a K and L switch, made in Japan, $50 including tax, (photo below). Today I installed the switch, rode around the neighborhood, then let the bike idle in the driveway to see what happened. Idling in the driveway with the new switch, the fan turned on at about 3/4 into the white zone and the fan stayed on until the gauge went down to about 1/3 into the white zone. I let it cycle like this two or three more times - problem solved.

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