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Discussion Starter #1
My bike very slowly runs hotter and hotter in the summer. I'm limited to 90 minutes of riding because that's when it starts to get into the red. The warm up is very slow.

Testing temp with an IR thermometer I'm showing 250F at the thermostat housing, about the same at the top of the radiator and varying between 160F-200F at the bottom of the radiator when the gauges reads on the edge of the red (bike idle, fan on) (IR readers can be a bit finicky so some of the variation could be the instrument). I'm thinking about taking the radiator to a radiator shop for a rod out. The bike was left sitting for some time before I got it. I installed a new OEM thermostat about a year ago. Based on the temps provided does it sound like the radiator is cooling properly?

-Robert
 

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romeobravo172
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Have you ever done a good rad and system flush,changed coolant? Like on a car can be a lot of things to cause what you describe. A simple air bubble can cause problems if not purged correctly. Can also go to a 75% water and 25% coolant mix seems to help!
 

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Discussion Starter #3 (Edited)
Have you ever done a good rad and system flush,changed coolant? Like on a car can be a lot of things to cause what you describe. A simple air bubble can cause problems if not purged correctly. Can also go to a 75% water and 25% coolant mix seems to help!
Thanks. On a car I get air bubbles out by running high RPM. The bike has been running like this for awhile and I do go up pretty high on the RPM during acceleration. Is there anything else I can do to push out any bubbles? (I did think about bubbles but figured I'd run enough high RPM that it may not be an issue).

Hmmm, I just noticed in the service manual that there is a procedure for bleeding air out of the system using the bleed nipple. Could it be that I have air in the system after multiple rides? Is the air that stubborn? I guess I'll try their bleeding procedure.

-Robert
 

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romeobravo172
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On your thermostat housing there is a bleeder valve on the top to do that, not much difference in height than the fill cap, think trick is to fill (say after flush or fluid change) very slowly!!! Someone posted on here great pics on doing a coolant drain and change, ck that out. Think there is about 5 drain plugs to do it.
 

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Discussion Starter #5
Well I bleed the system but got no air bubbles. Bike is still very slowly getting too hot. Next step will be to remove the new thermostat and see if it still gets too hot without the thermostat. If that test doesn't work the next step will be to rod out the radiator. I'm still limited to 90 minute rides in the summer.

-Robert
 

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Sounds like your temp sensor is bad. Everything sounds like it is working in the proper heat range. If you remove the thermostat it will run cooler, not hotter. make sure you do a good system flush.
 

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Patriot Guard Rider
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Is it possibly the thermostat was installed backwards? I hate to admit it but I've done that on my truck once. :doh:
 

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Discussion Starter #8
Sounds like your temp sensor is bad. Everything sounds like it is working in the proper heat range. If you remove the thermostat it will run cooler, not hotter. make sure you do a good system flush.
IDK. 250F seems really hot. Even for a modern car with emissions, etc that would be hot.
You are correct, the purpose of removing the thermostat is to see if the bike no longer overheats. If it does, that indicates a restricted thermostat.
I think that there is a lot of long term benefit of a system flush, but for the purpose of solving any specific mechanical issue I think its snake oil. The only part of the cooling system narrow enough to actually plug up is your radiator and a plugged up radiator vein can't be flushed because it has no flow. In my experience the only way to correctly fix a plugged radiator is to remove the top and bottom and rod it out. Fortunately we have a couple shops near here that do that all day long. Good welders.

-Robert
 

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250 is to hot, there is some sort of restriction in your system. I read wrong, I thought you said it was running about 160-200 and the gauge was reading 250.
 

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One thing I haven't seen anyone touch base on, Take a light and shine it through the backside of the radiator while looking through the front to make sure the cooling fins aren't clogged up with road grime and dead bug parts. Radiator gets more flying debris than anything on the bike. :doh:
 

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Discussion Starter #11
Pulled the thermostat and went for a ride in order to test if the restriction was the thermostat. It was a cool evening (high 70F's) but eventually I was still able to reach the top of the normal area. The needle was right on the line at the edge of the red section. So on Monday I'll take the radiator down to the radiator shop. Usually they measure the flow, give me a % restricted, etc so it will be very obvious to them what is going on. Probably just a rod out I''m' hoping. No leaks.

-Robert
 

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Discussion Starter #12
SOLVED! I just went for an hour ride at 100F outside. Did some in town riding and some freeway driving. No longer overheating!!

I took the radiator to a radiator shop. They put the radiator in the basin and looked at how long it took water to run up the radiator with just garden hose pressure. That confirmed the restriction. Then the guy used a really cool tool that takes the garden hose as well as a shop air line and it blows high pressure water through the system. After some black stuff blew out water was blowing out the radiator like a fire hose! I'm not sure what this tool is but I want it! I'm assume its using air to pressurize or pump (i.e. increase pressure) of the water. I don't think its just aspirating it.
They didn't even charge me since it went so quick. I gave them $20 for their lunch fund.

-Robert
 

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...cool beans....but if it happens again, I suggest flushing with a vinegar mix (safe for aluminum)...just blowing it out wont get the caked on deposits...
 

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SOLVED! I just went for an hour ride at 100F outside. Did some in town riding and some freeway driving. No longer overheating!!

I took the radiator to a radiator shop. They put the radiator in the basin and looked at how long it took water to run up the radiator with just garden hose pressure. That confirmed the restriction. Then the guy used a really cool tool that takes the garden hose as well as a shop air line and it blows high pressure water through the system. After some black stuff blew out water was blowing out the radiator like a fire hose! I'm not sure what this tool is but I want it! I'm assume its using air to pressurize or pump (i.e. increase pressure) of the water. I don't think its just aspirating it.
They didn't even charge me since it went so quick. I gave them $20 for their lunch fund.

-Robert
It's just a cheap version of a pressure washer.
 

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Discussion Starter #15
Hmmm, I have a commercial grade gas pressure washer. If I could figure out a way to interface it with the radiator I guess I could have blown it clear. This device had a cool rubber rounded tip that fit a variety of radiator outlet sizes.

-Robert
 

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To much pressure will blow it up. Garden hose has about 35 psi, about the same as running pressure. Commercial pressure washer 3,000 psi+
 

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I always thought something like this might work:

http://www.plumbingsupply.com/snake.html#clogbuster

The expanding bulb will seal off the radiator opening and the hose pressure should do the rest.

Never tried it on a radiator, but I know it works on my drains.
 

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Discussion Starter #18
To much pressure will blow it up. Garden hose has about 35 psi, about the same as running pressure. Commercial pressure washer 3,000 psi+
My municipal pressure is around 45psi but my pressure washer is 2800 psi. I'd love to find a way to interface my pressure washer with the radiator for future use.

Sadly most of the radiator shops are gone. Most radiators are mostly plastic today and not really repairable. When my car radiator got a crack in the plastic side tank I just went to Autozone and bought a new one for $200. In my older car I'd take my radiator to the radiator shop every 6-7 years for a rod out and to weld any leaks. No more.

-Robert
 
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