sounds good max

id be interested to set mine about 97 c ...just below the theoretical boiling point (as the glycol mix most of us use artificially raises the boiling point a little .)

now just have to figure out the values and which one (s) to change 

thanks for the insight ..cheers !

I will leave mine well alone and assume that BMW knew what they were doing when the fitted this relay. As your cooling system is pressurised, it will not boil till it is well above 100c.

bikerboy wrote:I will leave mine well alone and assume that BMW knew what they were doing when the fitted this relay. As your cooling system is pressurised, it will not boil till it is well above 100c.

I´ll second that, there is hot in here and I never had an issue due to the fan set points, Ill spend my efforts on a clean system, good radiator cap and healthy fan.
Hope this helps.
Best regards
JAP

bikerboy wrote:I will leave mine well alone and assume that BMW knew what they were doing when the fitted this relay. As your cooling system is pressurised, it will not boil till it is well above 100c.

The 60:40 water:glycol mix recommended by BMW with a 1-bar radiator cap should be good to a boil-over temp of ~250 °F.  The idiot light turns on far before that, ~230 °F. The concern isn't about risk of boilover. 


There is some possible improvement for engine life (maintaining operating temperature at a tighter window (not cooler than designed though) is better). Even running the fan 100% of the time would not cause the operating temperature to go lower than allowed by the thermostat (think freeway operation: it goes to 85 °C, and never really varies, even on long, steep grades, loaded down). One advantage is the fan comes on more often, which prevents failures of the fan motor due to disuse. The second advantage is a reduction in radiated heat, a big deal on the faired bikes.

Hi there, my fan turns on only on heavy traffic or at long stops, don't know if a more frequent fan cut in will be good for the battery.
Regarding the light, mine has never turn on, perhaps its not working, but never been in the temp-meter red zone.
The radiator cap opens at 248ºF but, if the system is working properly that should never happen.
Best regards
JAP

japuentes wrote:Hi there, my fan turns on only on heavy traffic or at long stops, don't know if a more frequent fan cut in will be good for the battery.
Regarding the light, mine has never turn on, perhaps its not working, but never been in the temp-meter red zone.
The radiator cap opens at 248ºF but, if the system is working properly that should never happen.
Best regards
JAP

That's the normal action for a K bike. I have a datalogger on my bike with the custom fuel injection. In traffic the temp creeps up to 216 °F before the fan comes on to take it down to 212 or so. Freeway is exactly at 185. In general, you want stable temperatures, which is why some people install a manual fan switch. 

I've had the temp light come on once, that was near WOT on I-80 in nebraska, passing a truck, while the weather was 100 degrees, with a stuck thermostat (that didn't open or close fully, from what it seems. The fan/horn fuse had blown from both (horn being a stebel nautilus) being activated at once. 

Battery wise, it shouldn't be a big deal. K bikes have plenty of leeway with power, especially with the 50 amp alternator.

wmax351 wrote:That's the normal action for a K bike. I have a datalogger on my bike with the custom fuel injection. In traffic the temp creeps up to 216 °F before the fan comes on to take it down to 212 or so. Freeway is exactly at 185. In general, you want stable temperatures, which is why some people install a manual fan switch. 

I've had the temp light come on once, that was near WOT on I-80 in nebraska, passing a truck, while the weather was 100 degrees, with a stuck thermostat (that didn't open or close fully, from what it seems. The fan/horn fuse had blown from both (horn being a stebel nautilus) being activated at once. 

Battery wise, it shouldn't be a big deal. K bikes have plenty of leeway with power, especially with the 50 amp alternator.

Hi your data logger shows your bike is behaving as per design, fan cut in temp is 217ºf (103ºC) Cut out 212ºF (100ºC) bike runs at 185ºC (85ºC) on open road. Seems that original design considers 185-212ºF (85-100ºC) stable enough.
Normal condition at witch the temperature will rise is in on heavy traffic/stop, that means low rpm / idle and the alternator is not really charging the bat under 2000 rpm, so I think the designer choose to let the engine work hotter but safe, to save battery.
That´s why I stand by the original design, perhaps with the more powerful and heat demanding configuration resulting from the custom FI the original cooling system design will need updating, that´s part of the fun and the future, once original FI will not be available. Then hope us to be around to need it.
Best regards 
JAP

japuentes wrote:

wmax351 wrote:That's the normal action for a K bike. I have a datalogger on my bike with the custom fuel injection. In traffic the temp creeps up to 216 °F before the fan comes on to take it down to 212 or so. Freeway is exactly at 185. In general, you want stable temperatures, which is why some people install a manual fan switch. 

I've had the temp light come on once, that was near WOT on I-80 in nebraska, passing a truck, while the weather was 100 degrees, with a stuck thermostat (that didn't open or close fully, from what it seems. The fan/horn fuse had blown from both (horn being a stebel nautilus) being activated at once. 

Battery wise, it shouldn't be a big deal. K bikes have plenty of leeway with power, especially with the 50 amp alternator.

Hi your data logger shows your bike is behaving as per design, fan cut in temp is 217ºf (103ºC) Cut out 212ºF (100ºC) bike runs at 185ºC (85ºC) on open road. Seems that original design considers 185-212ºF (85-100ºC) stable enough.
Normal condition at witch the temperature will rise is in on heavy traffic/stop, that means low rpm / idle and the alternator is not really charging the bat under 2000 rpm, so I think the designer choose to let the engine work hotter but safe, to save battery.
That´s why I stand by the original design, perhaps with the more powerful and heat demanding configuration resulting from the custom FI the original cooling system design will need updating, that´s part of the fun and the future, once original FI will not be available. Then hope us to be around to need it.
Best regards 
JAP

That is definitely the normal behavior. Nice thing with the datalogger is I identified the bad t-stat. 

The temp light coming on was with the stock efi system, though with a somewhat tired engine probably operating below ideal conditions. 

A lot of people really want the fan to come on lower, especially with the LT's. I feel the lower on temperature would be preferable to the manual switch. http://www.motobrick.com/index.php?topic=4274.msg26048#msg26048

With my custom efi, I can actually set it to control the fan (or other switched items) as well. I'll probably implement this at some point. I can add in a condition that it only turns the fan on at lower temperature only if the battery voltage is high enough.

One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

Yeah. Hook it into the speed sensor. Less than 10-15kph the fan cuts in at a lower temp.

Unless the system detects you have a tea bag in the overflow bottle. No one wants a cold cuppa while waiting for traffic.

rossko wrote:

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

Yeah. Hook it into the speed sensor. Less than 10-15kph the fan cuts in at a lower temp.

Unless the system detects you have a tea bag in the overflow bottle. No one wants a cold cuppa while waiting for traffic.

Speed sensor would be difficult to do. With the custom EFI, I could do RPM based easily. 

At highway speeds, the fan turning on would not be detrimental. I was thinking putting it to 200 °F, gives a 15 degree window.

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

I'll bet you that the fan does not operate at all if you are doing more than than about 20 mph. Why would it, the forward motion at that speed would probably put more air through the radiator then the fan will.

bikerboy wrote:

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

I'll bet you that the fan does not operate at all if you are doing more than than about 20 mph. Why would it, the forward motion at that speed would probably put more air through the radiator then the fan will.

and

RicK G wrote:

bikerboy wrote:

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

I'll bet you that the fan does not operate at all if you are doing more than than about 20 mph. Why would it, the forward motion at that speed would probably put more air through the radiator then the fan will.

and

I am just saying that BMW designed the fan to cut in when stationary at the temperature that it does.  Stationary would be the only interest to them as when the bike is moving the fan has no function.

bikerboy wrote:

RicK G wrote:One thing that would be good to have would be that the fan cuts in earlier if the bike is stationary so that say  sitting waiting for road works the engine wont get as hot before the fan cuts in but if out on the highway all acts as it was designed.

I'll bet you that the fan does not operate at all if you are doing more than than about 20 mph. Why would it, the forward motion at that speed would probably put more air through the radiator then the fan will.

Here's a scatterplot from my datalog, going from Fremont to Berkeley on a ~90 degree day, with both traffic and clear freeway. The legend on the right is the "hit count," basically  how many times the value was observed. The lower speeds are pause and go lanesplitting, so there is time for the engine to heat up at lower speed. Constant 40mph is pretty much thermostat temperature. 




Here's one from a cooler day, with no traffic. 

In the upper plot, during your mixed riding trip, the mean coolant temperature at 40MPH hovers around 201°F (93 °C), and peaks around 213 °F (100 °C).  I presume that the fan did not kick in until the overtemperature relay reached its setpoint of 218 °F (103 °C).  Those temperatures were not achieved until you had slowed to below 20 MPH.


If I were to take a guess as to what you will achieve with this modification,  if you were to then take a data logging of a similar trip with a programmed setpoint of say 203 °F (95 °C), I presume that you would cap the peak temperatures of the coolant in that range.  The effect on the graph would be to compress it vertically, with only rare cases where the coolant temperature exceeds 203 °F (95 °C).  It would make the graph look like a very squished "figure 8" (whereas today it looks like a fuller "figure 8").  Is that correct?

robmack wrote:In the upper plot, during your mixed riding trip, the mean coolant temperature at 40MPH hovers around 201°F (93 °C), and peaks around 213 °F (100 °C).  I presume that the fan did not kick in until the overtemperature relay reached its setpoint of 218 °F (103 °C).  Those temperatures were not achieved until you had slowed to below 20 MPH.


If I were to take a guess as to what you will achieve with this modification,  if you were to then take a data logging of a similar trip with a programmed setpoint of say 203 °F (95 °C), I presume that you would cap the peak temperatures of the coolant in that range.  The effect on the graph would be to compress it vertically, with only rare cases where the coolant temperature exceeds 203 °F (95 °C).  It would make the graph look like a very squished "figure 8".  Is that correct? 

That would basically be the case. It would keep the temperatures from bumping above the setpoint during stop and go traffic and low speed riding. So it would remove the red blob at 40mph, 215 degrees, and truncate it to 205, or whatever the setpoint was. In the case of the megasquirt system, I can control for hysteresis, and not turn the fan off till the temp goes down below a certain point, which is lower than the trigger point.