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Discussion Starter · #1 ·
14 8R, runs great pulls hard, no real issues except. Living in SC gets very warm here. When I get stopped at light or in traffic, temp goes up, fan comes on, all good, right. But temp keeps going up, even with fan running, until I get moving again. Am I correct in thinking that I have a bad thermostat? Not the most mechanically inclined, but can get enough done to avoid trips to shop for most things. Any help is greatly appreciated. Everyone ride safe
 

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Could be a thermostat slow to open (there are two), but bleeding the system on these bikes is not simple as you need to raise the front end by 50cm. If somebody changed the coolant and didn't follow this step then there may be air trapped.

How much coolant is in the expansion tank?

Are the radiator fins all clear of obstructions and not bent over?
 

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What temp is the fan comming on? 2013 and up, the fans come on about 214 degrees to 220 they will stay on till operating temp wich is usualy around 178 to 181. If you at a light its common to be at 206 to 214 degrees then is should drop once you get going to 60mph
 

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Full Throttle
2008 RC8 / 2007 690
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6,856 Posts

This might be your easy fix
 

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Full Throttle
2008 RC8 / 2007 690
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6,856 Posts
Any help is greatly appreciated
idle it with the rad cap off all the way to fan on ,
Some bike combos run hotter.
Before i started changing stuff on mine it could run hot at the lights in summer.....

May aswell do a coolant drop and to up imo
 

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Discussion Starter · #6 ·
idle it with the rad cap off all the way to fan on ,
Some bike combos run hotter.
Before i started changing stuff on mine it could run hot at the lights in summer.....

May aswell do a coolant drop and to up imo
Swoop and Cors,

Fan comes on at 190 as I installed the KTMTwins thermostat at purchase. Though, that might also be the issue. Was installed 6 years ago, coolant changed once as I only have 3800 miles on bike. Thanks for everyone who has reached out, I appreciate the info. Ride safe
 

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Full Throttle
2008 RC8 / 2007 690
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So your thinking that regardless of fan on or off , the heat keeps rising?


Couple of things come to mind .fuel pressure check. Needs to be between 48-52psi.


Disable the 2nd throttle bodies by forcing them open using what's called the 100% map...
 

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ok i agree with cors he knows these bike very well but we still need to know if the temp does goes down once you get to 40 to 60 mph and what temp is the bike reading then? just to get a base line. Temp is always going to go up at lights or idle wich is why the thermostat is installed to make the fan come on early but even then the bike temp will still go up at idle
 

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Discussion Starter · #9 ·
ok i agree with cors he knows these bike very well but we still need to know if the temp does goes down once you get to 40 to 60 mph and what temp is the bike reading then? just to get a base line. Temp is always going to go up at lights or idle wich is why the thermostat is installed to make the fan come on early but even then the bike temp will still go up at idle
Swoop,

Yes temp comes back down to 190 when riding. Main reason for my concerns is other bikes I have, the temp comes down when fan comes on. Of course though, the are unfaired so that would help I assume. I appreciate all the responses as I am 4 hours from a dealer which I would rather not do. Again everyone ride safe
 

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ok good, it seems to be the bike is running normal. Cors can check me on that. My bike has no thermo switch and like i said its common op temp is 174 to 181 at 60 and at lights as high as 214 the fan comes on at 220 im told. then back to 60 its drops to 181 no over heating or running problems and that's with 54000 miles on it and no tune ups missed, all done by the shop except oil change. I think youll be just fine bud!
 

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Full Throttle
2008 RC8 / 2007 690
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bike is running normal.
Only thing i can add is what HKP recommended.
A decent air bubble in there wont expand enough to set off the rad cap pressure release so the bubble limits idle flow yet driving flow it doesnt show up as problem...
But if the air bubble in the cooling system is big enough , the air expands and motor shut off you get a splurge come out the rad cap, but just a little smaller air trapped in there wont set that off.
Ive done an idle heat cycle with the cap off and topped up when i could .
But having something like a hot rear cylinder really peaks the over all heat aswell at the lights.
Ive done a lot of map swaps and its pretty amazing how some maps run alot cooler and some are cookers.

i would do some heat cycle test at idle with or without air filter, self clean the injectors, dump the fuel, pull the fuel pump out and get a high pressure hand held pump sprayer and spend some minutes squirting fuel in the tank holes , check fuel filters that the inside one isnt perished and hard....
 

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Discussion Starter · #12 ·
Only thing i can add is what HKP recommended.
A decent air bubble in there wont expand enough to set off the rad cap pressure release so the bubble limits idle flow yet driving flow it doesnt show up as problem...
But if the air bubble in the cooling system is big enough , the air expands and motor shut off you get a splurge come out the rad cap, but just a little smaller air trapped in there wont set that off.
Ive done an idle heat cycle with the cap off and topped up when i could .
But having something like a hot rear cylinder really peaks the over all heat aswell at the lights.
Ive done a lot of map swaps and its pretty amazing how some maps run alot cooler and some are cookers.

i would do some heat cycle test at idle with or without air filter, self clean the injectors, dump the fuel, pull the fuel pump out and get a high pressure hand held pump sprayer and spend some minutes squirting fuel in the tank holes , check fuel filters that the inside one isnt perished and hard....
Thanks to all for the great info. So good to have such a helpful community for one of the best bikes out there. Cheers to all and ride safe
 
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