Replacement Radiator fan

dolau

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OK- so I am not going to pay £300 for a new radiator fan and second hand ones are rare as hens teeth so ..... looking on Ebay there are various 'universal' radiator fans for £10-15- so I though might as well try one- what have I got to lose- if it doesnt work I can use it to cool me in the shed in summer

So- I need to measure the diameter of the fan and I will do that tomorrow but just wanted to check my schoolboy physics on the wattage of the fan

The Yamaha manual says a 20 amp fuse protects the fan and the system is 12 volts do to me that is 240 watts= 20ampsx 12 volts

Seems most of them have a <100watts motor I should be well in with the bike power system and maybe fuse it down to the correct wattage for whichever one I fit.

Thing is- will the inbuilt thermostat and ECU work with a fan that isnt the OEM fan or should I wire in a switch or a strap on (ooooh Betty - sorry thats an English joke from my generation) thermostat

Anyone else tried this money saving idea?
 

dolau

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Excellent find- i missed that

I have brought it- well £45 with postage and I would spnd £25 on a chance

Thanks for spotting it Yamaboyz- much appreciated

But that still begs the question.... will a cheapy alternative work?

Answers on a postcard
 

zoner

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My experience with dirt bikes has shown that fans are not highly technical. Just moving some extra air through the radiator for when speeds are below about 20 mph gets the job done. The only time I notice the fan running on my FZ is when it is left running while parked.
 

RJ2112

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Excellent find- i missed that

I have brought it- well £45 with postage and I would spnd £25 on a chance

Thanks for spotting it Yamaboyz- much appreciated

But that still begs the question.... will a cheapy alternative work?

Answers on a postcard

You would be well served to modify the installation, to include a deflector on bottom edge of the mount to keep debris out of the replacement. The fans die when they get jammed and burn out. (Not a very good design, IMHO)
 

YZF73

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dolau

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I knew I had seen that on here somewhere- that will be my winter project... that and a thorough clean and grease before spring

Cheers guys!
 

dolau

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Checking the other designs including gutter guard I am assuming that the pebbles get chucked up the back of the radiator and lodge under the fan housing not come through the radiator core.

Also another idea that was on here was a lower amperage fuse to protect the fan motor from future failure. I guess no-one wants to test their fan to destruction to see what fuse protects it and I guess from past experience Yamaha will not help with any information- shame
 

YZF73

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Checking the other designs including gutter guard I am assuming that the pebbles get chucked up the back of the radiator and lodge under the fan housing not come through the radiator core.

Also another idea that was on here was a lower amperage fuse to protect the fan motor from future failure. I guess no-one wants to test their fan to destruction to see what fuse protects it and I guess from past experience Yamaha will not help with any information- shame

I've been thinking about this recently. You'd have thought the fuse would pop before the fan gets damaged. When you get the new one, could you post up what is written on the label on the back of it? You never know, might show some specs...


Yamahaboyz


Edit: Just had a look at the specifications for the '01 R6, which uses very similar fan, and found that it has a 7.5A fan fuse compared to the FZ6's 20A. As the fans are similar I'd have thought the amperage would be similar, definitely not more than double!!! I think I'll test it starting with a 7.5A fuse and work up to the minimum rating fuse that doesn't blow... should provide the best chance of protecting the fan if it were to jam. I'll make sure I post the results afterwards.
 
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Motogiro

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Keep in mind that the impedance of the fan when it starts can be much different using more starting current as it starts. After the motor is spinning it will draw less current. I agree that you would not think there was that much difference in current draw between the r6 and FZ6 fans... :)
 

YZF73

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I've been thinking about this recently. You'd have thought the fuse would pop before the fan gets damaged. When you get the new one, could you post up what is written on the label on the back of it? You never know, might show some specs...

Yamahaboyz

Edit: Just had a look at the specifications for the '01 R6, which uses very similar fan, and found that it has a 7.5A fan fuse compared to the FZ6's 20A. As the fans are similar I'd have thought the amperage would be similar, definitely not more than double!!! I think I'll test it starting with a 7.5A fuse and work up to the minimum rating fuse that doesn't blow... should provide the best chance of protecting the fan if it were to jam. I'll make sure I post the results afterwards.

I've just tested the fan fuses as promised. 5A fuse blows the instant the fan is switched on, however a 7.5A has survived at least 7-8 fan start ups so far (with the bike stationary).

I can't yet confirm that this fuse will survive indefinitely as the fan would draw more current to start if there were more resistance to its movement in a certain situation (possibly the effect of wind on the fan whilst the bike is moving, I'd have thought this would actually try to spin the fan in the correct direction though rather than hold it stationary).

I'll keep everyone posted on whether it lasts, but it can be said that replacing your radiator fan fuse with at least a 10A, if not a 7.5A, is much more likely to save your fan in the event that it become jammed.

I'll start a separate thread later on explaining all this to try and draw people's attention to the issue, hopefully this might save some folks some cash on replacement fans!


Yamahaboyz
 

Motogiro

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I've just tested the fan fuses as promised. 5A fuse blows the instant the fan is switched on, however a 7.5A has survived at least 7-8 fan start ups so far (with the bike stationary).

I can't yet confirm that this fuse will survive indefinitely as the fan would draw more current to start if there were more resistance to its movement in a certain situation (possibly the effect of wind on the fan whilst the bike is moving, I'd have thought this would actually try to spin the fan in the correct direction though rather than hold it stationary).

I'll keep everyone posted on whether it lasts, but it can be said that replacing your radiator fan fuse with at least a 10A, if not a 7.5A, is much more likely to save your fan in the event that it become jammed.

I'll start a separate thread later on explaining all this to try and draw people's attention to the issue, hopefully this might save some folks some cash on replacement fans!


Yamahaboyz

Good work!

Some things that might be in the picture are that the fan's lower resistance and higher starting current are based on the impedance/resistance that are present when the armature hasn't gotten to it's speed. This causes higher resistance because of the time the brushes are running current through each winding on the armature. As the armature speed rises to it's intended speed, the time that current is flowing though each winding is decreased. There is also resistance when starting a static object to get it into motion as well as some hysteresis created from magnet field interaction on the motor's start up.

Hysteresis - Wikipedia, the free encyclopedia

The repetitive heat on the lower amperage fuse element may degrade it.

What might be a good project for the same protection would be a current limiting circuit that would limit current before it was at a dangerous level and output a signal to you that there was a high current problem with the fan. :)
 
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