My 04 600RR (38K miles) has been running hot. Really hot. I've owned multiple 600RR's and I know there is something seriously wrong. My bike runs 200F in 55F weather while cruising at 70mph. Below 40 mph, my fan is on 100% of the time and the temps sometimes climbs to 233F. My fan is on so much that my battery voltage falls below the safe zone and my bike will barely have enough voltage to restart if I shut the motor off. Rarely do I see the temps go below 198F. I've done a cooling system flush, and am running 50/50 pre mix. The cooling system is squeeky clean. I pulled the thermostat today and checked it's operation by heating it up to 185F and it opens with no problem. At 190F it is wide open. I'm thinking I may have a leaking head gasket, or either a bad radiator. My radiator is dinged a bit on outer left edge, but nothing major. Any suggestions?

 

Just a thought but is it really hot like do you get heat coming from the engine when sitting at red lights or could it be a faulty temp sensor giving up false data.

 

If its a head gasket, you have to be losing coolant. Are you?

 

The odd part is the bike doesn't feel hot at all. Not one bit. I'll check the temp sensor.

 

Nope. No coolant loss. But it may be a small leak causing air to leak into the cooling system? I'm going to double check and run a hydrocarbon/block leak tester.

 

Even then, you'd lose coolant from the gases expanding and pushing coolant into the reservoir - blow-out. If your bike is going through heat cycles, and the level is staying at the top of the radiator, you're not getting a leak or air into the system.

If thats the case, I'm with Matti.

 

True. I'll check the resistance of the ECT sensor.

 

The problem has taken a new form.

This is what I have done since last time:

-Block test. There is no combustion leakage into the cooling system, meaning that the head gasket is out of the question.

-Replaced the thermostat and gasket for preventative purposes

-Bled the air out of the cooling system

-Coolant Temp sensor works with no issues

Now my bike runs great on the highway. It averages at around 180-190F on the freeway. However, I let my bike idle in a stand still (5-7 mins) to check the condition of the fan switch. The fan kicks on at 220F, but the temp keeps rising while the fan is on at full blast. 221, 222, 223..229!!! Fearing that my temps would continue to rise, I rode around the block for 5 mins and my temp lowered to 210. It seems like at idle, the heat is not dissipating well enough even with the fan. The fan should kick on at 220F and the temps should lower, but that is not the case. After examining the radiator, there is a fat dent on the bottom far left of the radiator where the fan sits.... Could that be causing my problem?

 

Sounds like normal temperatures to me. 229 is where a full fairing bike sitting still will run. That little fan will not bring the temperature down. It will only keep it from going over 230.