Ive owned my 01 F4i since 2008. Until recently (last 3-4 months) Ive noticed the temperature going high, and the fan not kicking in. The temp gets over 240. It reached over 250 once and luckily it was just as I was pulling in to a parking spot at school. Normally I'll do research trying to solve issues, which is why I rarely/never post.

Ive read posts on checking the fan. "Ground the wire and test if the fan runs". Check, It does. "Fan switch might be bad". Went ahead and bought a new one. (not that expensive)

Also checked why it could be getting so hot. "Could be a bad thermostat". Bought a new one (Buddy at Honda hooked it up). "Check the Fluids". Completely flushed the fluid out and put brand new Engine Ice, which i noticed keeps the bike cooler longer, but eventually reaches up to 245-250.

I'm guessing it could be the radiator? There are no leaks anywhere, but the radiator is a little beat up, (previous owner looked like he stunted and smashed the front tire into it when landing a wheelie, which seems strange because I didn't think that could happen, but the dent fits the wheel) But like I said before, it ran cool, so maybe that problem caught up? I just don't know if I want to invest in a new radiator. No $$$.

Sorry for the long post, I appreciate all of the help I can get. I'm usually pretty bust, but I'll try to check back as much as I can.

-Solo

 

I'd err on the side of caution and get a new radiator, or at the very least a used one that has been tested.

 

the temp sensor i assume would give the ecu proper temps at which point should turn the fan on? meaning the temp sensor is working?
i'd hate to say it but could there be something wrong with the wire heading from the fan to the next in line for it to turn on, relay, ecu whatever. it's getting voltage obviously.
did you touch the wiring harness in any way or anything that a frayed wire could be worsened? the wiring diagram is missing out of my pdf manual otherwise i would look up what may be in line with it

 

You can check to see if the fan works by grounding out one of the wires for it on the frame, do a quick search and I'm sure you'll find it. Doublecheck you don't have anything blocking the fan from turning physically too, mine didn't work when I got the bike because it was clogged up with grime and rocks.

 

im having the same problem now. it use to be fine but now my bike reaches 240 as i pulled into my driveway. the fan does turn on at 235 however and the temp drops to about 230. radiator was never damaged. however i never did a coolant flush. maybe its just the 100 degree weather i was just riding in...

 

Confirming the accuracy of your temperature gauge might be a good idea. If you know anyone with an infrared thermometer to borrow it might be a good idea or buy one for around 20 dollars online, carry it with you while you ride and measure your temp at the radiator inlet and outlet when the temp is getting high, then read it on the hose as well because those things read funny sometimes on painted surfaces. The manual provides specifics on resistance for the temperature vs resistance of the sensor. Bottom line is that the thermometer takes the guess work out of things and if the issue is that the fan is actually not kicking on you have a fan circuit issue. Its a simple circuit with a temperature switch that turns the fan on and off and thankfully its easy to get to. There are other issues that are rare which cause over heat situations and are intermittent. Example is an air (combustion gas) bubble in the coolant from a very small internal leak like a head gasket starting to fail that only leaks some of the time. If the bubble encases the fan switch it would inhibit it from kicking on.. or could cause the thermostat to not operate properly. With your radiator in question, I would nail down the actual temperatures and go from there.

 

Everything on mine regarding fan/temp/thermostat works properly.. but I changed the way it's configured so that I can switch the fan on manually because if I reach 230 and I'm about to pull out of traffic.. I certainly don't need the fan.

So my first question would be why you're even hitting 245 degrees + . It's pretty hard to hit that temperature without just sitting idling for like 10 minutes.

Oh I also decreased my temp by a good 10 degrees by using some water wetter. Now personally I'm tweaking my ECU so.. sometimes I could be running a tad lean depending on the temp (cooler temp, denser air = leaner).. which would cause it to run hotter.

 

Thanks guys for all the input. Every little bit helps!!! I never really have time to do work on the bike, but i'll try to keep updating my overheating status. I'll try to confirm the accuracy of the temp along with fixing the fan.

The bike only reaches high temperature when its not moving (obviously) As soon as I begin to ride, it reduces it's temperature pretty quickly and mantains it at around 170-180 while constantly moving. Only when I stop it reaches that high. I'm hoping its because of the fan and not what Bryce said, because that just sounds horrible.

 

i found a seller on ebay that sells new radiators for 135. i wished i found out before i bought one from another seller for 185. lmk if you want the link

 

You're absolutely right! It was the relay/ecu, or whever the fan gets power from.

I'm not sure if this is a bad idea, if so please let me know, but i fixed the problem by directly running power from the battery to the fan, and left the temp switch plugged in so when the bike hits around 222-225, the fan will kick on. Ever since ive fixed her she's been running great! Thanks for all the help guys/gals!!

Again if it is a bad idea to run power directly to the fan please let me know

Thanks

Solo