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Here is a purely hypothetical question.

When I am sitting in the parking lot called "I-5" in the middle of Seattle, cursing the designers of the Washington state convention center. (Building straddles I-5 right in the middle of Seattle, and chokes the MAIN arterial down to 2 lanes...) I often watch my thermometer rise up and up and up, until my fan kicks on.

Anyhow, here is the question I had. When stuck in traffic, or for extended periods of idling, would it be better to keep the engine speed as low as possible, thereby reducing combustion strokes and thermal output of the engine, OR would it be better to race the engine a bit (1.5 to 2k RPM) thereby increasing the speed at which the water pump circulates the coolant through the radiator with the fan blowing on it?

I suspect I know the answer, but I figured I'd pose this to you guys, and give you something to think about.
 

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My fan comes on at nearly every stop light I hit. SinceI happened to have my DMM hooked up on the way home today, I know for a fact that my voltage drops to battery level when idling. Especially when hot and the fan comes on. I'm going to set my throttle lock at about 1500RPM when sitting at a light to keep the water moving AND keep a little charge going into the battery!

Bob :11grey:
 

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philcsand wrote:
Here is a purely hypothetical question.

When I am sitting in the parking lot called "I-5" in the middle of Seattle, cursing the designers of the Washington state convention center. (Building straddles I-5 right in the middle of Seattle, and chokes the MAIN arterial down to 2 lanes...) I often watch my thermometer rise up and up and up, until my fan kicks on.

Anyhow, here is the question I had. When stuck in traffic, or for extended periods of idling, would it be better to keep the engine speed as low as possible, thereby reducing combustion strokes and thermal output of the engine, OR would it be better to race the engine a bit (1.5 to 2k RPM) thereby increasing the speed at which the water pump circulates the coolant through the radiator with the fan blowing on it?

I suspect I know the answer, but I figured I'd pose this to you guys, and give you something to think about.
Increased water circulation isn't going to help all that much. Pumping the water faster just pushes it through the radiator faster so it cuts the time available to transfer it's heat to the ambient and you will generate more heat if you burn more gasoline. On the other hand, when the fan is running you may need to kick up the idle to keep the battery up.

My guess in this situation would be to idle at the minimum speed that kept the battery voltage up just to the point where the battery isn't discharging. That way you can run the fan indefinitely without discharging the battery but burning the minimum amount of fuel to reduce heating. Right or wrong that's the strategy I'd use.

:waving::15red::waving:
 

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Keepint the revs up won't circulate the coolant through the rad faster, it will only circulate it faster within the engine (probably heat it up faster) until the thermostat opens and then it will circulate into the rad for cooling. Can't see you gaining anything from this. I'd say that fitting a seperate switch to the rad fan will work better as you can turn the fan on yourself in those tricky situations.
 

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englishted wrote:
Keepint the revs up won't circulate the coolant through the rad faster, it will only circulate it faster within the engine (probably heat it up faster) until the thermostat opens and then it will circulate into the rad for cooling. Can't see you gaining anything from this. I'd say that fitting a seperate switch to the rad fan will work better as you can turn the fan on yourself in those tricky situations.
I can't see any advantage installing a fan switch, it will come on automatically when the heat rises to a point that it's needed. The thermostat will already be open in the conditions Phil is describing so the coolant will be flowing through the system.

Damn, I love the Mercer Mess! The I-5 choke really helps us bus drivers who are paid by the hour!
 

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I would have thought that an extra switch would keep the coolant in the radiator cooler, but you battery will probably struggle to keep up. I wonder if you can get a cooler thermostat for the bike instead? You can get them for cars, so why not bikes?
 

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Cooler thermostats are available for the wings, but why would you want the engine to run cooler? Engines require the specified OEM temperature settings to burn off oil contaminants. I've alwaysset the engine idle where the book states it should be. GL1200's idle at 1,000 +- 100rpm. Never had a problem even when riding in Fort Myers Florida in July. As long as the cooling fan is cycling on and off, the engine should be fine.

Also, if a manual cooling fan switch is installed, it will run the battery down over time because you would tend to run the fan longer than the sending unit is calibrated for. Honda figured this in so the cycling would tend not to drain the battery at idle...

Just my 2 cents... :)
 

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Renegade wrote:
Cooler thermostats are available for the wings, but why would you want the engine to run cooler? Engines require the specified OEM temperature settings to burn off oil contaminants. I've alwaysset the engine idle where the book states it should be. GL1200's idle at 1,000 +- 100rpm. Never had a problem even when riding in Fort Myers Florida in July. As long as the cooling fan is cycling on and off, the engine should be fine.

Also, if a manual cooling fan switch is installed, it will run the battery down over time because you would tend to run the fan longer than the sending unit is calibrated for. Honda figured this in so the cycling would tend not to drain the battery at idle...
Not to mention you'd be replacing fans, those little brushes wear out faster than the ones in the alternator do and I don't think they are replaceable! The point is that most of these bikes have performed fine over the years, if they aren't now the best response is to find out what when wrong and fix it, not try to modify it to cure a symptom.
 

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philcsand wrote:
Here is a purely hypothetical question.

When I am sitting in the parking lot called "I-5" in the middle of Seattle, cursing the designers of the Washington state convention center. (Building straddles I-5 right in the middle of Seattle, and chokes the MAIN arterial down to 2 lanes...) I often watch my thermometer rise up and up and up, until my fan kicks on.

Anyhow, here is the question I had. When stuck in traffic, or for extended periods of idling, would it be better to keep the engine speed as low as possible, thereby reducing combustion strokes and thermal output of the engine, OR would it be better to race the engine a bit (1.5 to 2k RPM) thereby increasing the speed at which the water pump circulates the coolant through the radiator with the fan blowing on it?

I suspect I know the answer, but I figured I'd pose this to you guys, and give you something to think about.
I guess since it is a hypothetical question , then any unsupported or illsupported theory would suffice. Like covering the engine with dry ice....
 
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dean_3326 wrote:
philcsand wrote:
Here is a purely hypothetical question.

I guess since it is a hypothetical question , then any unsupported or illsupported theory would suffice. Like covering the engine with dry ice....
Hey dean_3326 :waving: I guess your right. :clapper:

:weightlifter::18red::weightlifter:
 

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Be glad you're not on an air-cooled "V-Twin" in that traffic !
 

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wingdawg101 wrote:
Be glad you're not on an air-cooled "V-Twin" in that traffic !
Wish you hadn't said that, I'm wondering if there's a market for HD and V twin riders for water cooled pants!:cheeky1:
 
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