CBR250R over heating....Please Help

[Midge]

I know there is another thread on this but didn't want to just barge on in there.

I have just recently change the spark plugs in my bike and in order to do that i had to unbolt the radiator and take a pip off it of course spilling fuild. I topped it back up how ever its over heating. This is the first time it has over heated it was usually pretty good bike heating wise.

It doesn't matter if im riding it or just sitting there within a few minutes it off the clock on the temp gauge. When i look at the fan while its over heating it doesnt seem to be spinning, now im not sure if it only meant to spin while you ride it or if it does when your not? Could that be the reason? Or is it something else.

Cheers for any help guys

[R6_kid]

disconnect the fan and attach it to a 9v battery (the little square ones)... it should start spinning. If it doesn't then the fan motor could be dead. If it spins, but doesnt when the bike heats up you either dont have enough water in the radiator (but the temp gauge is going up?) and may need to bleed trapped air out of the system.

Otherwise your thermostat could be poked and rather than replacing it (generally the whole radiator) you can simply fit a switch for about $4 from dicksmiths... this will mean that you have to turn the fan on and off, but it should help with the cooling.

[Midge]

To bleed the air out i take it i just disconnect the lowest pipe let 1/2 the water come out??

will try these things you say today

[slimjim]

no sometime it does not pay to remove a pipe, it should have a rad cap on the radiator, remove thid like a car one and allow motor to run without the cap on ,in time you should see the water level lower a bit, thats cause the air should have been expelled , put proper coolant back in and fit cap tight, remember that it draws water from the header tank to return expelled water so don't over fill the header tank!!!! bad news if both things are over filled, could pop a hose or viens in radiator, fan works normally via a censor in water passage,so don't play around with this . if it aren't broke ,leave it alone

[NinjaNanna]

If you've removed the radiator and since putting in back in your fan no longer comes on, I have a strong suspicion that you either forgot to reconnect the Fan Thermo Switch, or haven't connected it properly.

The Fan Thermo Switch is usually screwed directly into raditator and should have two wires connected to it. When the water gets too hot, the switch closes which turns your fan on.

I'd be looking at this.

[Midge]

Cheers guys ill have a look at all these and get back with how i got on

[Paddy Blake]

As far as i know the temp switch is on the engine and the fan switch is on the
rad.If there is not enough coolent in the rad it might not be up to the level of
the fan switch and will not trigger it to make the fan come on.

Paddy.

[Midge]

OK so here's where i am at now.

I had a look at the radiator and there is no cap on top i fill it up from under the seat into a tube into the resivour. It does look like it has enough water in the radiator as the level has gone down since i last topped it up just before i found it over heating.

The fan does work however, i went for a quick run up and down the road to see if i may have solved the problem and just before the red line i stopped and had a look to see the fan going. When i brought it home i idled it to the red line and the fan was no longer going?? The thermastat plug thing i checked is in right.

She is still over heating any ideas?

Cheers

[Midge]

I guess the next question if nothing works out would be does anyone know of any good Motorcycle garages in Christchurch that specilize in hondas?

[NinjaNanna]

OK so here's where i am at now.

I had a look at the radiator and there is no cap on top i fill it up from under the seat into a tube into the resivour. It does look like it has enough water in the radiator as the level has gone down since i last topped it up just before i found it over heating.

The fan does work however, i went for a quick run up and down the road to see if i may have solved the problem and just before the red line i stopped and had a look to see the fan going. When i brought it home i idled it to the red line and the fan was no longer going?? The thermastat plug thing i checked is in right.

She is still over heating any ideas?

Cheers

I had a very similar thing happen on my 1995 ZX9 just a few months ago. The switch that turns the fan on went faulty. The strange thing was,

The first time that the fan should come on it did, after the coolant had been cooled slightly by the fan it would turn off as it should.

The problem was that each time the fan would turn on at a higher and higher temp than it was supposed to. I replaced the switch and it is fine now.

I was lucky, I was able find the correct switch by cross referencing it with the catalogue at Super Cheap Auto. They could have got it in within 2 days but I was lucky enough to find one at Repco. The switch cost me $40 not sure what it would have been through Kawasaki.

Also I doubt that your bike doesn't have a radiator cap (they aren't usually directly on the radiator like with cars), you probably just haven't found it. From what you've explained your reserviour probably has 2 or 3 hoses going to it. Follow each of them back and one will most likely take you to your Thermostat and Raditator cap.

Also has your bike always gotten close to the redline??? I'm not sure if this is normal, I would expect your fan to be coming on much earlier, but then again it might be normal for a CBR 250?


Cheers

NN

[R6_kid]

OK so here's where i am at now.

I had a look at the radiator and there is no cap on top i fill it up from under the seat into a tube into the resivour. It does look like it has enough water in the radiator as the level has gone down since i last topped it up just before i found it over heating.

She is still over heating any ideas?

Cheers

that is your problem dude. DO NOT RIDE IT UNTIL YOU HAVE THIS SORTED or you will blow up your engine (ask hurricane_r... i had to buy him a new one)

the radiator cap is under the tank at the top by the steering head. take the seat off, take the tank off (make sure you turn the fuel tap to off) and you will see the radiator cap there.

[Midge]

I have taken the whole radiator off and i swear there was no cap on the top of it.

Thanks alot guys i left it for a day cos i was fed up but had to take it to work this morning it seemed to be running fine so i figure ill take it for a quick blat after. It seemed to be normal back to its old self. What ever i did it seemed to help so cheers for all your help everyone. Thanks alot!