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Discussion Starter #1 (Edited)
i just purchased a 2002 k1200rs and have only ridden it about 300 miles
the temp gauge when riding is at the normal temp line or just below
if i stop in traffic it goes up to about half way between the normal temp line and the overheat lines
is this normal?
i started it and let it come up to temp it started creeping up past the normal temp line and niether of the fans came on , is there a relay that controls both fans?
if not what should i check first
 

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That creepy gauge...I'm seriously considering updating mine to something with proper graduations someday.

But Yes yours is normal, the fans should start when the gauge is about 1/8 to 3/16" from the Red Line. But let it Idle for a while, they should start. If not they may be defective, you would not be the first with a defective fan(s). Just make sure both of them come on.

It is a little unsettling at first to see the gauge creep up so close from the Red before the fans come on....but normal. :thumb:
 

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bke7 said:
i just purchased a 2002 k1200rs and have only ridden it about 300 miles
the temp gauge when riding is at the normal temp line or just below
if i stop in traffic it goes up to about half way between the normal temp line and the overheat lines
is this normal?
i started it and let it come up to temp it started creeping up past the normal temp line and niether of the fans came on , is there a relay that controls both fans?
if not what should i check first
Do a search ... this is perfectly normal. the fans don't kick on until you just enter the red zone. If the bike truly overheats, you'll see the dash light come on.

To properly test, just put the bike in Neutral and let it idle. The temp will run up until it just touches red, then both fans will kick-in and bring the temp down to mid-scale.
 

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Discussion Starter #4
thanks for the info
it is a little un nerving to see the temp go up
i will keep an eye on it
 

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They don't stay cool if idled. When I first got mine I started killing the engine at a red light until I realized it would actually over heat if i left it running. Yes, it is a bit unnerving.
 

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Therein is a conundrum. If you kill the motor when hot there is no water pump so the residual heat cannot escape. If you keep the motor running at idle in theory the bike should survive with both fans running, but the radiator is too small so the bike struggles and if you are lucky in Summer may only get the gauge below the redline until riding. You need to be riding above 30-40 mph for the normal airflow to drop the temperature to fans off.

Curiously after doing some tests I found the water flow quite poor at idle which partly explains why the motor doesn't cool so well. But at 2K rpm there is a big improvement. I think it is all to do with the conventional bypass arrangement in their cooling system design. If they'd used a smarter thermostat that closed the bypass path when the water was hot, the pump efficiency at low rpm would have been higher. Plenty of cars now have this system.



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When I was killing the motor I was doing it as soon as I arrived at the light. In other words before it got hot.
 

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I've been looking at the specs here:

Coolant temperature switch on temperature 115 C (239 F)
Fan on temperature : 105 C (221 F)

So it looks like only 10 C between the time the fans switch on and the temperature light would come on. Pretty close....but you could add an adjustable controller to get the fans to come on earlier. May help in traffic. Cheap anyhow, easy to try and reversible....! I know it has been done on some of the earlier Ks.

But you could test that easy enough by rigging a temporary on/off switch to the fans, activating them earlier and see if that helps.I don't know if I am willing to disconnect the fans and see where relative to the gauge the light would come on, that way I could calibrate that gauge.... Hum....maybe.....!!! :thumb:

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I think folks worry too much about that temp gauge getting close to the red line. I've got 104,700 miles on my '03 GT riding across the desert southwest. I live in Nevada, and have ridden across Arizona, New Mexico, Utah, and Texas in the heat of summer, triple digit temps. I've never worried about that temperature gauge. The fans kick on at the appropriate time and drop the temperature down even on the hottest days. The only time I've ever had the light come on was climbing up Mt. Evans road in Colorado (was riding to the top, 14,000 foot peak). I was going up a steep extended grade behind some cars. At 25-30 MPH and under load, with a car in front of me, the temp light popped on. I pulled over and let the traffic clear a bit, then ran the speed up to 40-ish which cooled it right back down.

Relax, its not a big deal as long as the fans kick on and the temp light stays off.
 

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I agree that gauge watching is futile and that the bikes work just fine. Now here is the "but"...

What about mounting a switch to manually turn the fans on for additional cooling. I live in Florida and commute on most days. During rush hour there are several intersections where I know I will not get through the light. It may take two maybe more cycles and the motor will get hot. It would seem that a switch to turn on the fans before the motor gets really hot might be beneficial. My IROC is the same way as the RS. Loves to run, gets hot when not.
 

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Sunchaser said:
I agree that gauge watching is futile and that the bikes work just fine. Now here is the "but"...

What about mounting a switch to manually turn the fans on for additional cooling. I live in Florida and commute on most days. During rush hour there are several intersections where I know I will not get through the light. It may take two maybe more cycles and the motor will get hot. It would seem that a switch to turn on the fans before the motor gets really hot might be beneficial. My IROC is the same way as the RS. Loves to run, gets hot when not.
Yep, should be easy enough to rig a two way switch, one side fans on at all time, the other side back to OEM system.Would have to be an idiot light on that switch, them fans are wimpy,expensive and prone to failure, wouldn't want to forget them on and burn them. :thumb:
 

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Cooling is only an issue for city commuters and those who like riding in tunnels.

You can ride 100's of K miles in hot temps with plenty of ram air and any contribution from fans would be relatively small, downside is more fan on time means less life and they aren't cheap.

Watch where your gauge sits in cold weather. That's the temperature at which the thermostat is properly regulating. In Summer for cities and stops the temperature rises because the cooling system isn't big enough and neither are the fans. Once the gauge moves up the thermostat is fully open and the cooling system is unstable. The oil cooler won't do much at city speeds either. This is what happens when you pack a big motor in a small space and is probably the design compromise they had to make.



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Discussion Starter #13
thanks all
i think that my real problem is that i ride everyday and sometimes get stuck in traffic
the temp drops down pretty quickly once i start moving , but it is the standing that has me concerned.
if you have been thru this and it is not a problem let me know
the other day it was only 68 degrees and it got hot in a hurry, so i cant imagine what it will be like when it is 95 degrees
maybe the adjustable controller would be the answer
 

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Doesn't the LT have a fan behind the oil cooler? I know the GS guys were looking at such for their bikes, they are much scarier than ours in traffic, LOTS of bars on the gauge.
Initially they were thinking computer fans, until someone mentioned "Waterproof".... :D
 

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I did think about that but decided that there was insufficient surface area on the oil cooler element to make much difference with small fans. You need big cu ft of airflow and a decent area of surface for the air to pass over with rapid heat conduction through the core.

The stock radiators may look wimpy and cheaply made, but they actually use a high performance thin aluminium core. It's just a pity they couldn't squeeze in another core row. That might just fix the bike for city riders, but I went with 1 extra fan on the existing cores which was cheapest. It proves that the existing rad cores whilst still small, can be made to pull more hot air away if you have more airflow. Notice on some of the big Jap bikes the rad is curved and wraps around the sides - that's to get the surface area and cooling efficiency up. If I was going to mess with the oil cooler and do a decent job, I'd think about replacing the element, fitting it in a duct with stone guard, fans and hang it low down in what little space there is behind the belly cover.

My extra fans cut in at mid temp range before the oems, most of the time they are sufficient to hold down the temperature and of course that's less running hours on the oem fans.



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Discussion Starter #18
thanks everyone
i am going to install the adjustable switch that way i can turn the fans on if i need to
 

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bke7 said:
thanks everyone
i am going to install the adjustable switch that way i can turn the fans on if i need to
Are you going with the controller that has an external temperature pick-up or are you plumbing one in? Or just a two way switch? In any case, let us know what you think of the results. :thumb:
 
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