Fan on/off - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #1 of 9 Old 04-15-2013, 10:11 PM Thread Starter
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Join Date: Mar 2013
Location: Scobey, mt
Posts: 20
Fan on/off

At what temperature does the fan turn on, I have never seen the fan come on on my 2010 klr, the temp gauge have been 3/4 up but I don't know if it would turn on at that temp..

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post #2 of 9 Old 04-16-2013, 12:30 AM
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Join Date: Oct 2011
Location: Lac La Biche Alberta Canada
Posts: 3,206
My Gen2 clymer manual says: Fan on 203f to 214f....Fan Off 189f.
Just leave your bike idling and the temp will rise till the fan comes on.

I was checking the fan operation on my gen1 while installing a TrailTech computer and found: Fan on 211f....Fan Off 208f. The Trail tech computer shows the actual temp.

I am wondering if this is OK and what to set the Temp warning lights to.

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Last edited by justjeff; 04-16-2013 at 12:36 AM.
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post #3 of 9 Old 04-16-2013, 02:20 AM
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Join Date: Jan 2011
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justjeff, you have a non-problem, IMHO!

Bike gets hot, fan comes on; bike cools down, fan turns off. I believe your cooling system works well within the range of safe operation; wouldn't mess with my own under those parameters.

But, your bike. And, I'll defer to more experienced, intelligent, and wiser posters.

Tson, to check your fan CIRCUITRY, short across your thermal switch terminals; this shunt should activate your fan (GENERATION 2 fan test procedure ONLY).

Not to put too fine a point on things; Generation 1 fan can be tested by grounding thermal switch lead, activating fan relay and in turn, fan. Generation 2 don't have no stinkin' fan relay; full fan current is carried through thermal switch (thingie in radiator); thus--a shunt (15 amp capacity) across the Generation 2 thermal switch terminals is required to activate the fan for test.
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post #4 of 9 Old 04-16-2013, 08:06 AM
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Location: Pefferlaw,Ontario
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Jeff you are correct, I have a Vapor also and can accurately watch the temps as they climb and fall. It is by far the best gauge out there to see exactly what our bike is doing. Temperature and speed are extremely accurate as you have found out.

I have double checked my vapor temp gauge against a thermometer and boiled water on a camp stove to see how accurate it's all but spot on, within a degree or two from my test thermometer made to see automotive coolant temps back in the day before thermal sensor guns.
I set my warning temps if I recall correctly at 220 for the warning and 240 for the hot setting.....but don't quote me on those numbers. It has been a while since I have looked at those number settings. I personally do not like the temps going through the roof as some say is ok to run them at. You have to remember depending upon what your coolant is diluted to whether it's 50/50 or 60/40 or weaker.....the boiling point will change. I run my coolant close to the 50/50 mark. I check it with the antifreeze tester for the freezing point and don't pay attention to the boiling point numbers. I set it close to the -35 degree point.

A long winded answer that isn't very precise,'s the best I can say other than it sounds like you both are within correct operating specs for sure.

If you want to see if your fan sensor is working, just put a piece of cardboard against the rad and wait for the temps to rise, just do not allow the temps to get into the red before shutting the engine off if the fan hasn't come on already. If you let it get into the red and above you could do damage to your engine from overheating. The rad cap should release but still not advisable to run the engine in the red.
You can over ride the thermal switch to see if the fan is working, but unless the thermal switch is working the fan will never come on.

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post #5 of 9 Old 04-16-2013, 10:38 AM
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Does any one know of a "cost effective" way to put a thermometer on the newer KLRs without having to get a Vapor? I've also wondered if my fan ever kicks on, I'm running a high volume of Water Weter, and my temp gauge never goes, so I'm pretty sure it hasn't turn on yet, but just the same, i would like to be able to read the water temp

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post #6 of 9 Old 04-16-2013, 12:21 PM
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Perhaps I'm missing your needs, but the KLR has a temperature guage that is pretty accurate.

For $19 you can add wattman's overlay and see what the temperatures are.

On the KLR it is typical for the temperature gauge not to rise during normal use; the cooling system is pretty effective and it runs cool in stock form.

If you fire it up and let it idle for a while you should see the gauge register higher temperatures with no air flowing through the radiator. It might even get hot enough for the fan to kick on.


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post #7 of 9 Old 04-16-2013, 02:25 PM
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I think the temperature gauge provides a valid indication; only . . . the temperature sensor is in the head, and the thermal switch is locted low in the radiator.

Don't know where the Vapor picks up its signal, but . . . some degrees of temperature difference exist between coolant near the cylinder head, and in the bottom of the radiator, I shouldn't wonder.

Regardless, if the temperrature gauge needle stays out of the DANGER zone, what? ME worry? (Apologies to Alfred E. Neuman.)
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post #8 of 9 Old 04-16-2013, 05:33 PM
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That's a pretty cool temp gauge overlay and that's pretty much what I was looking for, just a way to see the temp in degrees and not just hot or cold, and it's for my own curiosity, bike's running fine so I won't mess with it
Thanks again for the info!
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post #9 of 9 Old 04-16-2013, 07:00 PM Thread Starter
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Join Date: Mar 2013
Location: Scobey, mt
Posts: 20
Thanks guys
My bike don't run hot, I have never had it in the "red", but now when I have done some mods, I better check my fan, not that we have a lot of stoplights in NE MT, but you never know you might have to stop for some cows crossing the road/trail.

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