Heat and letting the fan run

[rambling]

Hi guys a question about heat. Just before reaching home I often need to go through a stretch of very congested traffic coupled with long red lights, at mid-day. When I reach the carpark the bike (CB500F) is pretty hot and the fan is running at max (I assume). Would you just turn off the bike completely or would you kill the engine but let the fan run for a minute or two before walking away? Do you think it makes any difference?

Cheers.

Edited November 7, 2014 by rambling

[Ozgur]

What I do is to keep the bike running for a while (idle running). Let the engine and oil cool down a bit.

[eisfeld]

I kill the engine but let the fan spin until it stops by itself many times when I think the engine is most likely very hot. I have no scientific answer but I just assume it might be good for the oil. Would appreciate if someone has a definite answer to this question, it's interesting.

[RubberSideDown]

Unless I get a warning light, I don't worry about it- as soon as you kill the engine it starts cooling down considerably- the fan will have a negligible effect on an engine that isn't running, and all you'll do is needlessly draw power from the battery.

[ll2]

i still let my bike run at idle or turn the key off and on and cool it with the fan a minute when i arrive home or office. just old habits:)

for air cooled engines it is important to run the bike idle for a minute of two but for water cooled modern machines, i believe it is not super needed.

also dont recommend using kill switch that often. instead just turn the key off and on. kill switches i believe have to be used only for emergency situations.

Edited November 7, 2014 by ll2

[ttakata]

I had a temp sensor on a 750cc bigbike years ago and the fan came on/off around 210 farenheit but it never seemed to go above 220 degrees even idling in LA traffic.

So I would let the fan run if I had time but never worried about it if I just shut it off.

I'm sure it helps the oil but has no affect on the engine's hard parts if you don't wait.

[papa al]

Refer to your owners manual.

No cool down necessary.

[Gnasher328]

Some bikes are designed for the fan to run on so maybe ther is a reason.

Idling doesn't sound a very good idea at all - my old air cooled BMW heats up more when idling than slow riding with airflow to cool.

[papa al]

Fans are traditionally thermostatically activated, so will run until the engine temp drops to the threshold.

With new 'smart' vehicles, ???

[Garry]

Idling & fan on, on fluid cooled engines will stop heat soak and will cool down the engine & cooling system uniformly.

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[Phra Ek]

If you switch off your engine I think the water pump will stop? It's a mechanical water pump on most bikes - so without the water circulation the radiator will be of little use and as the bike is not designed for air cooling (no fins) the fan will do very little to help cooling.

So either leave it idling with the fan running - or just switch is off.

Not sure which will cool it faster - but I think only turbo-charged engines have some benefit from idling whilst cooling as this prevents the oil cooking in the hot turbo?

[namdocmai]

I just turn it off, my bike has a temperature gauge and no matter what i do i have never seen it higher then normal temp.

[JonnyF]

Idling & fan on, on fluid cooled engines will stop heat soak and will cool down the engine & cooling system uniformly.

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My liquid cooled bikes tend to run around 85-90 in normal riding. When I leave them to idle for a few minutes e.g. at the lights, then they heat up to around 105. So I don't see the benefit in stopping a bike when it's at 85 and then letting it heat up towards 105 before turning it off. You have to turn it off eventually, so why not turn it off as soon as you stop when it's at 85?

[Garry]

Idling & fan on, on fluid cooled engines will stop heat soak and will cool down the engine & cooling system uniformly.

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My liquid cooled bikes tend to run around 85-90 in normal riding. When I leave them to idle for a few minutes e.g. at the lights, then they heat up to around 105. So I don't see the benefit in stopping a bike when it's at 85 and then letting it heat up towards 105 before turning it off. You have to turn it off eventually, so why not turn it off as soon as you stop when it's at 85?

Some bikes have poorly designed or damaged cooling systems. All because your bikes does this, does it mean that all bikes are the same. Not all bikes get hotter, though high air temperatures & humidity can exacerbate the condition. For example my Middle East spec R1 did cool down at idle. It had a very efficient cooling system. So did a buddies Fireblade. On the other side my Thailand Ducati 999 originally was a b$tch in the heat. I did some upgrades and the cooling system runs way more efficiently, this involved a new radiator & cap, quality coolant and fan control. I could say a lot a more about heat soak and a dynamic cooling environment, but I think I'll just start boring everyone.

Please consider that this is just my opinion, you can operate your bike as you so choose.

Cheers

Garry

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Edited November 11, 2014 by Garry

[T_Dog]

If you switch off your engine I think the water pump will stop? It's a mechanical water pump on most bikes - so without the water circulation the radiator will be of little use and as the bike is not designed for air cooling (no fins) the fan will do very little to help cooling.

So either leave it idling with the fan running - or just switch is off.

Not sure which will cool it faster - but I think only turbo-charged engines have some benefit from idling whilst cooling as this prevents the oil cooking in the hot turbo?

Driving cars in the mountains back in the USA, some cars with poor or defective cooling systems will boil over immediately if you turn off the engine after a long climb. Letting it run while it cools off keeps the water pumping past the hot bits while the fan and radiator dissipate the heat.

[Garry]

I've bought this for a future project, if I can get ZX1400/ZX14RR at the right price.

http://www.daviescraig.com.au/Electric_Water_Pumps-EWP80___Digital_Controller_Combo___Part_No_8007-details.aspx

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[ktm jeff]

Garry , i have seen these pumps for sale in England. Never used one (yet) but they offer a good replacement to a mechanical pump and offer much more control including varying flow rates. The subject of thermal (hydro) dynamics , heat sink and cavitation is interesting to some !. And usefull to know a little about in Thailand. When an engine is turned off , yes , the normal mechanical pump does indeed stop , but the thermostat - if fitted - is still open. This allows a slow but constant circulation of coolent due to a action called "Thermo-syphon". Water in the radiator cools through radiation , and as it cools it sinks (cooler water is more dense) this slowly cycles through the system , pushing the hotter water into the radiator to repeat the process. You could try different methods to see which works best for your vehicle if you have a didgital temp gauge (analogue is too vague).

[Garry]

Ah, someone who talks English (vague quote from the Avengers). I come from a dragracing background, so I'm a fan of variable and constant flow rates for cooling systems, whether the engine is in an dynamic or static state and why electric pumps are widely used. The pump listed above as you are aware goes a few steps beyond with having microprocessor control of the pump & fans. I'm not a fan myself of relying on thermal circulation (siphoning) by itself; too many uncontrolled variables and I'm a bit of a control freak. Thanks for responding

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Edited November 12, 2014 by Garry

[JonnyF]

Idling & fan on, on fluid cooled engines will stop heat soak and will cool down the engine & cooling system uniformly.

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My liquid cooled bikes tend to run around 85-90 in normal riding. When I leave them to idle for a few minutes e.g. at the lights, then they heat up to around 105. So I don't see the benefit in stopping a bike when it's at 85 and then letting it heat up towards 105 before turning it off. You have to turn it off eventually, so why not turn it off as soon as you stop when it's at 85?

Some bikes have poorly designed or damaged cooling systems. All because your bikes does this, does it mean that all bikes are the same. Not all bikes get hotter, though high air temperatures & humidity can exacerbate the condition. For example my Middle East spec R1 did cool down at idle. It had a very efficient cooling system. So did a buddies Fireblade. On the other side my Thailand Ducati 999 originally was a b$tch in the heat. I did some upgrades and the cooling system runs way more efficiently, this involved a new radiator & cap, quality coolant and fan control. I could say a lot a more about heat soak and a dynamic cooling environment, but I think I'll just start boring everyone.

Please consider that this is just my opinion, you can operate your bike as you so choose.

Cheers

Garry

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Fair enough, I guess it depends on the vehicle. Doesn't seem any benefit on my bikes unless it's gone over 105 and the fan has kicked in just before I reach my destination. In that case I'd leave the bike running until it was cool enough for the fan to stop running and then turn it off. Never happens in reality though...

Never had a bike that's cooler at idle than when moving though. Surely an efficient cooling system is just as efficient when the bike is moving, plus you'd have the benefit of the moving air dissipating the heat? Genuine questions by the way, I don't claim to be an expert.

[Garry]

Nor me, I just know what I know from personal experience

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[ktm jeff]

Drag Racing - the unperfected art of trying to slow down an engine explosion to 5 seconds . By which time youve done the 1/4 mile. Crazy engineering .

[Garry]

Drag Racing - the unperfected art of trying to slow down an engine explosion to 5 seconds . By which time youve done the 1/4 mile. Crazy engineering .

Though I love WSBK & MotoGP, my first love is still dragracing. I would love to build another turbo bike, though there would be no track surface at present in Thailand that could handle the horsepower (read: get the power to the surface without going up in smoke), but as a project I would enjoy. Donor bike would be either Hayabusa or ZX1400

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[ktm jeff]

Those Busa engines can take 350 BHP. I presume you know J F at Big CC Racing.Now im off to race round a track in ( Stourbridge ) for a few hours , using all the power the engine has available , and pushing the tires past their limit . OK , i admit it , im karting. He He.

[seedy]

Drag Racing - the unperfected art of trying to slow down an engine explosion to 5 seconds . By which time youve done the 1/4 mile. Crazy engineering .

Though I love WSBK & MotoGP, my first love is still dragracing. I would love to build another turbo bike, though there would be no track surface at present in Thailand that could handle the horsepower (read: get the power to the surface without going up in smoke), but as a project I would enjoy. Donor bike would be either Hayabusa or ZX1400

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Still want to build a drag bike, but the other thread said that Buriram will not install the strip for a while.

Found a few 'Busa and GSXR with no books for cheap - good place to start.

Maybe we form a team eh !!! Get shirts, a transporter, and Promo Girls !!

[ll2]

Drag Racing - the unperfected art of trying to slow down an engine explosion to 5 seconds . By which time youve done the 1/4 mile. Crazy engineering .

Though I love WSBK & MotoGP, my first love is still dragracing. I would love to build another turbo bike, though there would be no track surface at present in Thailand that could handle the horsepower (read: get the power to the surface without going up in smoke), but as a project I would enjoy. Donor bike would be either Hayabusa or ZX1400

Sent from my SM-T211 using Tapatalk

Still want to build a drag bike, but the other thread said that Buriram will not install the strip for a while.

Found a few 'Busa and GSXR with no books for cheap - good place to start.

Maybe we form a team eh !!! Get shirts, a transporter, and Promo Girls !!

seedy, i think there is a drag strip available close to Bangkok as K Speed will do a drag race even this Saturday on 15th of November and i am thinking of going there afternoon maybe.

I was not aware of this place but it is called Thepnakorn Motorsport Complex located at 53rd km of Rama 2 road. No website.

you can check it out if you are close to Bangkok.

[ll2]

looks OK.