Hot 4th Gen? Thermo? Fan Switch? Both?

Hey 4th geners:

So, I've noticed my fan seems to be caputz. Somewhere along the line last fall it quit on me. I've noticed my temp goes way up when lane sharing, or being stuck behind cars going slow up hill. Or just tooling along in slow traffic. It will overheat if I don't get around to get some air into it (pretty quickly into the red, I might add). When riding at speed, it goes back down to normal, relatively quickly. I know this heat thing has been discussed a gazillion times, but I haven't seen it regarding 4th gens.

So I think my:
1. Fan or fan switch is toast. I just noticed one day the temps going up and realized I hadn't heard my fan come on in awhile. Any experience with the actual fan dying? Or do you think it's probably just the switch?? Could the thermostat be involved? Seems like that to me! BUT, in conjunction with the fan not going on........

Any opinions? It's hard for me to imagine these two things both going out at once, but it is also hard for me to imagine the fan having such a radical impact in cooling when I am actually moving? Am I a fan ignoramus?????


Thanks in advance for any advice or opinions!!! (IMG:style_emoticons/oldemoticons/fing02.gif)

(I'd really like to hear that fan switches going out is very common, as it seems to be really easy to get to!) (IMG:style_emoticons/oldemoticons/rolleyes.gif)

My money is on the fan switch or fan. I was running my CBR600RR without a fan at the track, and if I cam in to pit at 220 degrees, if there was any traffic by the time I got to my pit it would be over 250 in a span of maybe 45 seconds.
I think if your thermostat were stuck closed you would be overheating with or without airflow.

jeremy556, Jan 27 2007, 01:34 PMI think if your thermostat were stuck closed you would be overheating with or without airflow.

Good point! What if it were stuck open? Is it possible?

Sounds like the fan. I'll have to test it!

very simple test.......
find fan conection block with 2 wires... open it..


take 2 long bits of wire and connect to the fan... it should start spinning...if it does.. you fan switch is dead..
if not.. the fan is..

Brown81, Jan 27 2007, 04:42 PM

jeremy556, Jan 27 2007, 01:34 PMI think if your thermostat were stuck closed you would be overheating with or without airflow.

Good point! What if it were stuck open? Is it possible?

Sounds like the fan. I'll have to test it!

Yes, it is VERY common in fact.
When the thermostat is stuck open, the bike will not get up to proper operating temperature. If your bike goes below 170 after warmed up, or never reaches 170, your thermostat is stuck open; usually people notice when their gas mileage goes to hell.

jeremy556, Jan 27 2007, 02:21 PMYes, it is VERY common in fact.
When the thermostat is stuck open, the bike will not get up to proper operating temperature. If your bike goes below 170 after warmed up, or never reaches 170, your thermostat is stuck open; usually people notice when their gas mileage goes to hell.

Well, 4th gen temp gauge is analog, so don't know the exact temps!! It pretty much depends on the air temp outside. When cold, engine stays cooler, and visaversa.


First thing I'll do is go ahead and check the fan, as gll429 suggested. If the problem persists, I'll replace the thermo. Thanks for the help!!

jeremy556, Jan 27 2007, 04:21 PM

Brown81, Jan 27 2007, 04:42 PM

jeremy556, Jan 27 2007, 01:34 PMI think if your thermostat were stuck closed you would be overheating with or without airflow.

Good point! What if it were stuck open? Is it possible?

Sounds like the fan. I'll have to test it!

Yes, it is VERY common in fact.
When the thermostat is stuck open, the bike will not get up to proper operating temperature. If your bike goes below 170 after warmed up, or never reaches 170, your thermostat is stuck open; usually people notice when their gas mileage goes to hell.

Interesting, would that (bad mileage) be 37/38 mpg on my 4th gen? I have heard near 50 mpg is possible and my temp gauge doesn't go up very high, no idea what the temp is.

steve_mn, Jan 29 2007, 08:56 AMInteresting, would that (bad mileage) be 37/38 mpg on my 4th gen? I have heard near 50 mpg is possible and my temp gauge doesn't go up very high, no idea what the temp is.

Probably not, I think when it happens it drops from like 40 to 18. I don't think 37 is bad at all, my is not stuck open and I get about 20mpg on the VTec (IMG:style_emoticons/oldemoticons/rolleyes.gif)