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Discussion Starter · #1 ·
My bike sat for the last 4 months or so, due to being dropped. It's finally back together so I took it for a ride, only to find that the fan isn't coming on. It got hot to the point of almost overheating. I shut it off and let it cool down. While cooling down, I noticed the fuse was blown. Swapped a new fuse and still nothing. After getting it home I tried spinning the fan by hand. It would only go so far then jam up. Pulled the fan out, bent the shroud back in place so it can spin freely. Wire back in and let it hang there. Started the bike up getting it warm. Once it got above the cold line I held it steady around 4,000rpm and the fan came on. As soon as I let off the throttle it shut back off. Even fully warmed up, or a little hot, it only comes on if I keep the revs up. The fan wont come on at idle. I'm on a really tight budget right now and don't want to spend money on parts I don't need. I'm thinking either the fan itself might be going or maybe the temp sensor. A local bike shop told me there is no relay for the fan but is there a fan switch?
Any and all advice is greatly appreciated.
 

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There is always a fan switch,its on the left side of the rad.I'm a bit confused,a fan shouldn't come on at certain revs,it comes on at a certain temp then shuts off once temp lowers past that point.
 

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partsguy said:
I'm a bit confused,a fan shouldn't come on at certain revs,it comes on at a certain temp then shuts off once temp lowers past that point.
agreed ............. presuming of course that the electrical system is OK ie there is enough smoke in the wires at low revs and the earths are OK.
 

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I agree with the above comments. It sounds like a possible battery or charging system issue. Can you put a meter on the battery while you repeat the above experiment and see what voltage you're getting at low/high rpms?
 

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Discussion Starter · #5 ·
Ok, just did a check with a multimeter. At idle, I'm around 12.2 volts. Holding the revs up between 3-5k I'm around 13.3 - 13.8 volts. Once again, while rev'd even before it was warm the fan is coming on. After I shut it off, I checked the battery and found 12.4 volts.
 

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Could it be a damaged wire or loose connection somewhere?

Im thinking that the engine revs are irrelevant, but its the vibration at higher revs that makes the electrical connection..... Just a thought???
 

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So you're saying the fan comes on at any temperature, warm or cold, as soon as the rpm's exceed a certain point, then shuts off when rpm's dip below a certain point, regardless of actual coolant temperature?
 

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Discussion Starter · #8 ·
So you're saying the fan comes on at any temperature, warm or cold, as soon as the rpm's exceed a certain point, then shuts off when rpm's dip below a certain point, regardless of actual coolant temperature?
Pretty much, yeah. That's what's happening. I'm thinking the fan switch (temp sensor) in the radiator
 

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Certainly sounds like the switch is frazzled. You could try measuring the resistance across the switch while varying rpm's. If it drops as rpm's increase you have your answer. It may also be a bad switch stuck in the 'on' position and an intermittent ground...
 

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shewie said:
It may also be a bad switch stuck in the 'on' position and an intermittent ground...
p19djg said:
Im thinking that the engine revs are irrelevant, but its the vibration at higher revs that makes the electrical connection
Combine those two and you have my best 'guess' based on the results of the charging test.
 

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:clap:2003 model user of a xx ... How much should I apply a mixture of distilled water and antifreeze fluid .... Thanks for your help in advance ... 50% - 50% of the mixture should I do? what brand of coolant should I use ... Thanks:clap:
 

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:clap:2003 model user of a xx ... How much should I apply a mixture of distilled water and antifreeze fluid .... Thanks for your help in advance ... 50% - 50% of the mixture should I do? what brand of coolant should I use ... Thanks:clap:
Most motorcycle coolants are now pre-mixed so no need for distilled water. If you find one that needs watering down follow the instructions on the bottle they are all different. Buy one that is compatible with aluminium and has rust inhibitors.
 

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theduck Thank you. normal driving is actually 140/160 km / h fast travel when I realized 80-82-84 degrees. I use a 98 degree fan operates in heavy traffic, but from time to time the 100/105/110/115/118 he rises, respectively. windy again to its former level immediately drops the traffic flowing I wonder should i worry about in any way? Is this normal or an abnormal condition or constitute Does your situation? the life of the cooling fluid, antifreeze wonder if this could not be completed? This problem may disappear in a new mixture? 2/3 of this mixture not changed at any time since years. in the meantime, please excuse my English. but thank you very much for your help.:clap:
 

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The temperatures you are seeing are not high, as long as the temperature drops to 86 or below when the traffic starts flowing everything is good!
The coolant should be changed every 2 years. This is worth doing since it stops corrosion as well as improving the cooling.

Your English is fine :thumb:
 

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I'm using Engine Ice which I doubt you can get there. However you can get Motul Factory Pro and the like and it's excellent.
 

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BB's have 2x different fan control systems depending on year - the early ones had a simple temp switch in the radiator that after a certain temp it simply earthed the fan and turned it on, later BB's had a more direct system driven by the ecu, so the first thing to check is which system your bike has, if it has the switch in the radiator then much easier to test and repair because it is independant of the ecu, you can simply earth the single wire going to the switch and the fan should come on regardless of temp or even if the engine is off
 

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My fan only comes on when im stoped in traffic for along time.It comes on when temp hits about half way on the guage and shuts down soon as im on the move and the temp goes to about 1/4 guage. It never comes on as im on the move with no traffic. I live in florida and it does get hot here.Im thinking thats how a fan should work.
 

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Jopa
Be advised this is an older thread. And it is also referencing a carby bike. They use a similar system as the early FI's but it also has a unique circuit that is tied into the choke circuit. When the choke is active the fan will trigger on. What i would suggest is pull up the service manual in the resource section here on the board. Walk through the checks they suggest and let us know what comes up. Also a detail description of your symptoms would help as well.
Good luck and keep us posted.
 

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... And it is also referencing a carby bike. They use a similar system as the early FI's but it also has a unique circuit that is tied into the choke circuit. When the choke is active the fan will trigger on.

Good luck and keep us posted.
The OP has a carbureted bike and the choke on those is all mechanical, so no circuit to tie into. I dunno about the '99 FI bikes: very different beast from the '97-98.

With reference to the original post, I suspect the fuse was blown because the fan blade was immobilized by the shroud being bent after the crash. After the OP freed up the blade, I don't think he reported a blown fuse.

Remember, the fan gets 12V as soon as the ignition is switched on (assuming wiring and fuses are good). All the fan needs is a path to ground for the motor to start spinning.

There are two "switches" that can activate the fan motor.The first is the fan switch that is screwed into the radiator. When the radiator gets hot enough, the contacts in that switch close, providing a path to ground to the fan motor.

The second is the "first idle relay". This relay is switched on by the ECM according to the wiring diagram. The following note is in the FSM on p 19-15: "The cooling fan motor will run automatically after 10 seconds, if the engine revs above 2,000 rpm with the transmission in neutral."

Don't ask me to explain why this happens or what it means. I'm just the messenger, but it seems to suggest that fan operation can depend on engine speed while in neutral irrespective of coolant temperature.

Perhaps someone can tell me what the "first idle" function is for?
 
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