Thermostat?

FM Rider

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Sep 9, 2015
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85
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Rotonda West FL
Was going down the freeway today and noticed the temp was fluctuating between 199 and 202. Was traveling about 70-75 and the air temp was about 83 degrees. Got off the freeway onto city streets and temp increased to 210 or so and as soon as I would stop for a light the temp would increase enough for the fan to kick on and that would reduce temp to below 212. Went about 10 miles to my destination and parked bike. When I went to return home temp was at 160 and from then on all was normal with temp at 168-170.

I'm assuming this is a sticky thermostat but is this a one time occurrence or could I expect the problem to reoccur and get worse? Coolant was changed 2 1/2 years ago and overflow level is stable between minimum and maximum lines.
 

~TABASCO~

RIDE ON ADV is what I do !
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I does sound like it... Ive replaces several... Get a new one and throw it in... What year is your bike? Miles?

Ive seen many "weeping" as well... If you see any antifreeze crustys around, for sure change it... Easy to do... make sure to TQ the bolts properly so it cant leak......
 

Fennellg

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I find my temp will always go up transitioning from highway to city stop and go. I always thought if I never got above 220 everything was ok. The fan kicks on and the temp falls.
 

escapefjrtist

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How heavy was traffic when the bike was running warm? I've witnessed hotter engine temps on both my FJR & Tenere when running in hot conditions and heavy traffic. I believe turbulent air in traffic disrupts flow through the radiator leading to increased engine temperatures. Tenere is even more susceptible to this with the sidewinder radiator.

~G
 

sandro1973

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Jan 26, 2018
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Portugal
I recently had to replace my thermostat when noticing the temps a bit all over the place, but mostly hotter than before, even when riding on a highway at moderate speeds in cold days. On stop signs, it would go hotter than it ever did.

There was no sign that the thermostat was working as it should, since temps should go down a bit when it reaches around 172 ( it's rated to open at around 160 ).

I replaced it and tested the old one....it was only fully opening between187 to 212 and it would take minutes to fully close even when exposed to cold water. So....it was taking too long to open and by then any cooler coolant wouldn't do much....than it would leave a partially open circuit for a while with hot coolant....

SInce getting a new one ( also replaced the temp sensor and radiator cap for good measure ) it now works flawlessly and runs cooler.
 

Squibb

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Aug 10, 2014
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Bedford, UK
Certainly sounds likely to be the thermostat.

The only other issues I can recall are the fan itself failing, often after dropping the bike on the left side, & the rad needing a clean to improve airflow.
 

Jlq1969

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If the radiator is dirty on the outside (insects or other obstruction), it will get hot faster, and it will take longer to cool down….that is, the water tends to be hotter for longer
 

Cycledude

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To me Your story sounds very normal for when the outside temperature is 80 degrees or higher when riding a 1200 Tenere. My previous 2013 and current 2018 seem to perform exactly the same as yours.
 

FM Rider

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Rotonda West FL
I don't believe 199-202 is a normal operating temp at 75 mph. Even in the heat of the summer it stays below 180 when cruising.
 

Jlq1969

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For folks living in warmer areas the radiator probably should have been a little bigger.
It’s that the larger size of a radiator does not necessarily imply more efficiency in heat exchange….the thickness of the pipes, the number of fins per square inch….can improve or worsen heat exchange….the construction material also, but copper and aluminum share the same exchange rate, copper being somewhat better.
If you look at the pics of a S10 radiator.And the KTM 1290 radiator, you'll see that the S10's,has one more pipe, and a narrower radiator (the one on the KTM is wider)... which would mean that it has more dissipating fins per square inch and that the pipes are thinner... Tlength of both is very similar
F552EEED-E1CA-4AEB-9F34-B4569C814C7F.jpeg741D6030-2C26-4C73-8CA4-FC2DDD95B753.jpeg
 

WJBertrand

Ventura Highway
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For folks living in warmer areas the radiator probably should have been a little bigger.
The stock radiator seems adequate to me. I’ve ridden across Nevada, Arizona and the Mojave deserts in August with temperatures approaching 120°F. The bike handled the heat better than I did! I do have the fan temps set lower via a tune (205 °F on / 195°F off) even with those settings the fan would not switch on as long as I was moving at normal road or highway speeds. In slower speeds and traffic, it managed to keep the temperatures close to 205°F. Never saw it reach 210°F.


Sent from my iPhone using Tapatalk Pro
 

cyclemike4

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Sep 18, 2016
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ky
Good idea to change the thermostat. that will give you piece of mind on that for sure. It may have very well have been the issue. I have seen my temperatures do exactly what you said happened to you and it was (like someone said earlier in the thread here) the cross winds causing my temperatures to change or run higher than usual. Don't be surprised to see that happen again in the right conditions.
 
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