Manual Switch for Radiator Fans?

[StrongEagle]

Looking at a 87 Aspencade to purchase. Seller showed me a rocker switch on upper right part of inner fairing, used to turn radiator fans on and off. Given that I've always (and only) seen thermostatically controlled fan switches, why would someone have done this? Gives me an uncomfortable feeling that a shade tree mechanic may have been associated with this bike in the past.

Thanks.

[Rednaxs60]

Looking at a 87 Aspencade to purchase. Seller showed me a rocker switch on upper right part of inner fairing, used to turn radiator fans on and off. Given that I've always (and only) seen thermostatically controlled fan switches, why would someone have done this? Gives me an uncomfortable feeling that a shade tree mechanic may have been associated with this bike in the past.

Thanks.

Can't quite agree. Lots of manual switches with rad fan on indicator light being used and installed on the 1200s and earlier models. These bikes operate with what Honda calls a "high efficiency" rad that is just sized to allow for good cooling while at highway speeds. Because the rad is sized this way, the engine operating temp in stop/go traffic and city driving will operate a higher temperature, generally such that the rad fan comes on. Most in the US call it a parade switch because of slow speed operation.

The rads on the earlier 1100/1000 GWs were larger, and do not fit the 1200 without modification being done.

The Aspencade has a digital dash. The engine temp indicator is in bars and there are 10 of them. Honda details in the owner's manual that normal engine operating temp is between 2 and 8 bars. If the engine temp goes above 8 bars, turn off engine and investigate why.

My '85 LTD operates at 4 bars on the highway and rad fan comes on when the engine temp is in the 6 bar range. If I'm in hot weather and stop/go traffic, I will turn on the rad fan and the engine temp will stay in the 5 bar range. Older bikes need a little more TLC.

It can also provide you with a get home aspect should the thermostatic switch fail. Nothing lasts forever.

The only issue I would want explained and demonstrated is that the rad fan does come on with the thermostatic switch. Have the seller start the bike and let it idle until the engine temp is in the 6 to 7 bar range and listen for the rad fan to come on if it gets to 8 bars, there may be an issue with the thermostatic switch. The manual switch is a fail safe for you.

I have friends who are still riding air cooled, or air/oil cooled bikes with no engine temp gauge. Ignorance is bliss in these cases.

Don't let the installation of this manual switch make you miss a good deal.

Hope this helps. Good luck

[CrystalPistol]

'85 GL1200A here:

I did that "add a fan switch mod" good number of years ago. As I recall, only ran one lead to ground, one lead to what was ground side of fan (normally temp switch was means of ground) and in on position, fan circuit is complate and fan fans. In off position, fan operates normally as OEM governed by thermostatic switch.

Rarely have I had need for continuous on fan but one really hot day in Boon, NC in heavy traffic 2 up and loaded, the bike started to look hot on those indicator bars so I flipped switch, fan come on and bike cooled down soon enough.


.

[StrongEagle]

Outstanding information, Rednaxs60 (thanks, too, to CrystalPistol)! I have some things to check out. The seller has let me ride the bike so getting it up to temperature and then checking thermostatic control won't be a problem. I rode it for several miles, when I got back the temp gauge was about 6 bars, owner then flipped switch while it was idling and I was listening to engine... given that my Valks were are thermostatic, I never thought about it much. Will definitely have to check if the fans operate properly... I am guessing this would be a thermostat/thermocouple issue that I will get to look up in my newly acquired repair manual.

I also want to run a compression check on it... I suspect it is varnished carbs since it has been sitting, and, while I wouldn't mind rebuilding carbs, dealing with a compression issue is something that I don't want to do.

Again, I really appreciate the background into things such as this.

[SilverDave]

About 5 years ago, after an over heating incident, I added a switch over-ride to my GL1200, with a LED light, near left thumb.
The LED comes on whenever fan is on : either switch or built in thermostat switch.
( I'll send you the circuit, if you want )
Its a fiddley install.. short 30 yo brittle wires, cramped for soldering .
Eventually I took rad out to get some working space, sent it out to be cleaned, "Rodded" and tested, and painted matte black. Also replaced thermostat, and pressure cap, new hoses and flushed entire system , new antifreeze .

It was a s close to original engineering as I could make it.

so...
Progress report after 5 years: The best part was the indicator LED. Every time I look at the " Bars"
and think " Its starting to overheat... the OEM thermal switch turns on the fan ...
I've seen the LED go on hundreds of times, mostly in city traffic....
But I've never actually had to use the override switch ... LOL


so Moral of the story : clean it all, and try to get it back to what the 1985 engineers had in mind .

SilverDave