My 97 CBR has been having an issue of stalling. Here is what happens... the temp has to high enough for the fan to come on. The bike is not overheating. While stopped at a stop light, the bike will stall unless I give it gas to around 2300 to 2500 RPM. Of course, all this does is create more heat while I am at a stop. It is a slow stall like it is beginning to run out of gas. All the air filters and fuel filter are clean. I have tested the air valve in the back of the air box and it passed. I also tested the fuel pump and it passed. Any ideas to what would cause this stalling when I am idling at a stop light and the engine is hot?

 

OK it's not over heating, but the engine is hot. Have you checked your coolant levels, and the condition of it?
Coolant should be changed at min of two years. It breaks down pretty quickly once its reached it's use by. Wot can happen then is that the boiling level is reached earlier. I can't remember the last time my fan kicked in, and it's probably only happened at couple of times in the 8 years I've had it. Other causes can be a faulty radiator pressure cap. or faulty thermostat/Water pump, it could even be something simple like old & crap plugs. (yeah I know, checking the plugs aint easy on these things) Is the bike running ok when you get going and it cools down?
Wot your describing could be alot of things (that cause overheating) all motors behave weird when they get to hot. To paraphrase Mr Horse," No sir, they don't like it, they don't like it at all"

 

The coolant is 8 months old as well as the thermostat. I suspected it and so I replaced the thermostat and the coolant. The coolant has been replaced every couple years if not more. I tear down the bike every spring and get it ready for the summer by lubing up the rear suspension, new fork fluid, valve lash, new coolant, and etc. I checked the coolant level and it was just fine. So, this would eliminate the possibilities of there being any coolant leak (the oil is fine too). In regards to there being gunk in the coolant system, I highly doubt that the coolant could coagulate in that short of a time period. I also checked the tell tale hole on the water pump and it is bone dry. About the only thing I have left to check is the radiator cap.
But yeah, as soon as I can get moving and push some air through the radiator... the problem is gone and the bike runs like a raped ape. The problem really rears it's ugly head when I am sitting at stop lights. Another thing, the bike’s thermostat doesn't shoot up to hot right away. It was doing that and that was why I changed out the thermostat. Now it warms at a nice gradual pace which it is what it should be.

 

I was curious to see if and what fixed your problem. I seem to have the same problem on my 96 CBR.

Ill run it for 20 minutes or so and itll get around the middle of the gauge and at a stop light it will die just like you described.It is not over heating but Im wondering if the heat has something to do with my problem.

 

Wish I could say that I've solved the problem, been a little broke. I can say this much though, the stalling is from the battery being drained from the load being put on it by the bike (lights, fan, etc). I've tested my battery and it failed a load test. This pretty much that the battery will show 12 + volts with a volt meter but when under a load will fail. If the battery is too low on our bikes, the bike will stall. The root of this issue I guess is, why is the bike getting so hot so quickly with perfectly good coolant? I haven't figured this problem out yet but I have been working on it here and there. I've noticed that my waterpump is leaking through the weep hole but I don't if this is enough to cause the problem. I just got a new battery but haven't used it yet, I'll can let you know how it goes. I think that replacing the battery is a bandaid because the bike will continue to run hot requiring the fan to run.