I have a 2000 CBR f4. It runs good but it acts up alot.
I didn't get many answers last time, so I thought i'd try again.
My bike pushes out a lot of hot air. It's uncomfortable on the legs at times.
Is it normal for that much hot air to come out of the bike ?
The temperature readings usually stay at 1/2 way. And the fan will kick on at that level, sometimes a little higher, but it always cuts on. When I'm riding, the temperature will stay at half until I come up to a red light.
If I wait more than a minute, my temperature gauge slowly rises until its right below red line. As I go to take off, it will sputter, sometimes cut off, sometimes high revs will get it going fine. Then temperatures lower as I ride on. Is that normal for sport bikes or is there something I could do ? I was told a valve adjustment, or thermostat could fix the problem. I figure it isn't a vacuum issue because it isn't happening ALL the time. Also, how pricy can a valve adjustment be ?

 

Sounds like you have a cooling issue. As the bike heats up at a light the operation is affected. Try the easy stuff first... flush and fill the cooling system wit new coolant. make sure you get all the air out of the system. Next would be the thermostat, but I am guessing that it is ok because with the bike moving the temp doesn't rise above half way. If the thermostat were frozen closed, it would overheat no matter what and if stuck open then when you were moving it could possile drop below half way on the gauge.

So, flush and fill with new coolant (something bike friendly without silica in it) and see what happens. You could also try using engine ice...this stuff is expensive but pretty good.

 

^ That is good advice.

Yes, feeling warm air btwn you legs is normal, esp in summer. The fan is going to facilitate that.

You can also use WaterWetter instead of Engine Ice but both are quality products. Personally, I use WW & ProHonda 50/50 premix.

As an owner of an F4, 1/2 way on the gauge is about normal op temp. Some increase in temp on the gauge is normal if sitting still in hot weather. However, red-line isn't normal.

Do what vfrman suggests above & follow-up.

 

I agree with both, I had that same problem even had my bike shut of at a stop light cuz over heated. I replaced it with WW and now it rarely touches the half way mark and I believe the only time I hear the fan turn on is when I warm up the bike.

 

well, i already have new coolant. that didn't solve the issue.
so, i guess the thermostat is my next step. My bike almost stalled
on me 3 times in a bout 5 minutes today. My bike HATES red lights.
I'm almost starting to think it could be electrical. But it would go to
die on me, i'd give it a little gas to keep it alive, then I had to give
it a lot of gas to get going. The RPMs were just fluttering like crazy.

 

The questions are; is the thermostat working & is the fan working?

 

If the coolant is fresh and you've done a flush as well, I would look at the thermostat.
They don't always freeze/fail, at full open/close. If it is stuck in a half-open it will restrict
coolant flow. Also, look at the pressure cap, although that's a reach if you aren't also
experiencing coolant loss.

As far as getting hotter at stop-lights, that is fairly normal. The radiator sheds heat
when fresh air is flowing through it. The fan is there to facilitate when the bike isn't
in motion. Since you are getting so close to the red-line, even with the fan assisting,
it leads me to think coolant flow restriction.

A thermostat is cheap, and not a bad idea for an older bike, anyway. If that doesn't
correct the problem, I would start thinking about the water-pump as the next step.
As opposed to electrical issues, since the only electrical system that directly affects
cooling is the fan, which you've already said works. So unless it is failing and not
spinning up to the proper speed, it shouldn't be a factor.

Hope these comments help, Ern