I have posted before about my 2007 running hot, not overheating but just running hotter than my previous bikes.

A few of you were experiencing the same issue while others were not. This lead me to do some research on the issue using my bike as the test subject and I now believe I have found the cause.

I started by doing all the checks as per the service manual only to discover the fan, thermostat and switch were all good.

The issue appears to be the cooling system needs to be bleed as it has air trapped in the system. I am not sure if it was the factory or dealer who filled the coolant but their was air in my system.
With motorcycles as opposed to cars air can get trapped in the system and not find it's way out without user intervention.

Prior to bleeding the system I would see temps while stopped in the 220-224 deg area now the bike does not exceed 219.

This is just what I found with my bike your issue may be very different.

 

Good find! That's a commonly overlooked solution. Some car's (mostly Japanese) have bleeder screws just for air in the system. The air can compress and allows morespace for the water to boil casing verheating. You can probably drop the temps more with water wetter.

 

thanks for the info, im gonna check that saturday.

 

Good find and excellent point. However, how should I go aboutbleeding the cooling system on an '03 636?

 

I just did a coolant change on my 03 636 yesterday. Following the service manual with the bike off and radiator cap off tap and lightly squeeze the hoses. Then I started up the bike (with the bike being cool at first) and then let it run (with cap still off) and tap and squeeze the hoses again. The manual also told me to let the bike run with cap off untill the fan kicked on but I'm pretty sure that was to make sure the reserve tank was filled up. Hope this helps.

 

Some have a bleeder valve but my 07 does not.

The process is simple for no valve.

Have someone sit on the bike and keep it level. Remove the radiator cap. Start the bike. While it is coming up to temp tap and squeeze the radiator hoses on both side to dislodge any air bubbles.

Rock the bike side to side. Once the thermostat opens shut the bike off. Fill up the radiator so it pushes coolant out when you put the cap on so you know that you are not trapping any air in their.

Next make sure you overflow is between full and low when the bike is cold and you are done.

Do not get the coolant on your paint wrap a rag around the radiator cap.