Hey all,
Well, a couple weeks ago we (my boyfriend and I) noticed that my bike was overheating (the temp gauge was almost at red line). So, after tracking down some issues, we determined that the fan wasn't kicking on because of the radiator switch not working. So, we replaced the radiator switch and the fan still doesn't kick on. It's supposed to put out a ground signal to turn the radiator fan on, but it's not. So, the next step was to hard wire the fan to run anytime the ignition was on to see if it still overheated. It did. So, maybe the thermosensor is bad causing the temp gauge to malfunction (i.e. saying the bike is overheating when it really isn't). So, we replaced the thermosensor and it's still overheating and the fan still isn't kicking on (when hooked to the radiator switch). On a cold start, it takes about 15 to 20 minutes for the temp gauge to go from cold to almost red line.
The water pump appears to be working and we flushed the radiator with a hose and it's still overheating.

Help!

Sarah

 

Ok, after going through the service manual, it says to test the thermo switch for the radiator, basically boil it to a temperature between 208 and 216 degrees F. I ended up letting the bike idle for about 15 minutes while checking the radiator temp with a laser thermometer. When the temp gauge is right at the red line is when the thermoswitch is seeing right at 208 degrees and the fan finally kicked on. Maybe the bike was just made to run hot?
I'm going to let it cool down for a while and then double check the fluids in it and then take it out for a ride and see how it does while running. It just makes me nervous letting the needle get up that high.

 

I have been racing a cbr600f for about 3 yrs and anytime I am waiting in line on in the paddock while the bike is idleing it will reach the red but as soon as you start moving it will drop right down, even when I drove on the street in traffic the bike would be really hot but as soon as you hit a highway it would cool right down, I figure they just run that way

 

I had this trouble when I flushed my prestone (water). Do you put water under thermostat. You do it.
remove the 2 screw near the cap and remove the thermostat et put prestone. If your thermostat is not in water it doesn't open.

Try this

(excuse my english...)

 

For overheating, here's what the Haynes manual says to check: Spark plugs fouled or incorrect type. Incorrect ignition timing, fuel mixture incorrect, air filter omitted, air leaks at carb fitting or hoses, float level low or fuel vent blocked. Also: engine oil low, old, or wrong viscosity, oil filter blocked, or radiator fins blocked. Funny, it doesn't mention the fan.

 

There might not be a problem. They make it so the fan kicks on at a really high temperature to pass emissions. My bike gets almost to the red before the fan kicks on.

 

I would make sure that you have enough coolant in the system. Air in the system/radiator can hold the coolant on top of it and make it appear to be full. The therm. measures the temp of the coolant (not the engine temp you see on your dash), so once the coolant gets hot enough, it will kick the fan on. If there's no coolant in front of the therm, it won't measure anything and will never turn the fan on. So after the flush you did, I'd measure the proper amount of coolant mixture you need in a pitcher (I have an 87 and my system holds 2 liters), and make sure it ALL gets poured into the system. Shake the bike while your're filling it up to get the air out. just a suggestion.....

jw