Computer fan on dirtbike

I saw a couple of threads concerning fans on yz400 series dirtbikes

Since I own a YZ426 and overheating in trails became an issue I decided to give it a try.

I decided to use the 92mm fans. 12 volts and .29 amps each    they have a molex conecter (standart hard drive power connector)

they fit snugly on the top with alot a clearance.    they are held in place with a ty-rap going throu the rad with another one in the front to lock in in place (didnt want to dammage the fins)

Power is from a 12 volt gel battey rated at 4 amp (scooter type batteries) that is locked in place with the air filter, and the switch is on the handlesbar

To charge the battery is fairly simple    I fabricated a adapter to plug my changer on the molex connectersof the fans 

So far it's still holding good and when I overheated I flicked the switch on right away and the overflowing stoped almost instantly. I have around 6-8 hours of run time on the fans with the battery presently  

 

More pictures to come

 

When a fan breaks   I'll simply remove the shrouds,unplug the molex connector and cut the tyraps to replace it

 

fan mod.jpg

For now it's drop of idle and prestone overflowing throu the cap.   However when I know i'll be idlelling to wait for peopleI simply turn the fan on to be safe.

I'll probably be installing a temp guage soon on it

Ive been planning on doing this to my kx450f. Im interested in seeing/knowing how you wired the battery to charge from the molex connecter. Did you wire one conecter straigt to the battery and the other to the charger? Where did you get the battery and the fans?

A few points to ponder.

  • Computer fans are not water proof or made to operate in an hostile environment like found off road. A real radiator fan will last much longer and be cheaper in the long run.
  • A battery in the air box will hurt top end performance. The airbox is typically barely big enough stock. The air filter needs a free flow of air to not be restrictive. A better place for a battery would of been a fender tool bag. Not as clean but more effective.

 

If/as you develop this idea, you may find only one fan is actually needed. You can put switches on both and watch radiator temps with something as simply as temp strips, they are self adhesive strips that stick to the top of the radiator and change colors on a scale to give temperatures. Cheap and effective.

Battery came from a scooter/moped shop (so it is rechargeable with a 2 amp car charger) , fans are computer fans from an electronic store (4.99 canadian) with already a molex on them.    I took a molex fan connector from a broken fan and I hocked it up to the wires comming from the battery.   The fans have a male-female connector at each end so you plug everything in line. Next the charger. Plug + with + and - with - on another spare molex connector and you hoke it anywhere with the fan connectors to charge the system.

 

I'll get more pics soon of the setup

8cm-PC-Case-Cooler-Fan-4-Pin-Molex-KCF-1000-.jpg

Edited by MrFreez82

Allright, thanks! I have a RC car battery (not a cheap store bought one) that I might end up using since since it is lightweight and would be easy to place.

A few points to ponder.

  • Computer fans are not water proof or made to operate in an hostile environment like found off road. A real radiator fan will last much longer and be cheaper in the long run.
  • A battery in the air box will hurt top end performance. The airbox is typically barely big enough stock. The air filter needs a free flow of air to not be restrictive. A better place for a battery would of been a fender tool bag. Not as clean but more effective.

 

If/as you develop this idea, you may find only one fan is actually needed. You can put switches on both and watch radiator temps with something as simply as temp strips, they are self adhesive strips that stick to the top of the radiator and change colors on a scale to give temperatures. Cheap and effective.

Obviously i'm open to all new ideas.    the issue with standard fans is the amps watts they draw and you have to find them with a max of 100mm  (the ones I saw draw 40 watts)     they will kill the battery fast     . 1 fan might be enough but i prefer running 2. I do not expect them to last very long either   I'm prepared to have a faillure fast on a fan     (thats another reason to have 2).

Edited by MrFreez82

My uncle did the same thing on his KTM450SX-F, also due to overheating. He connected it to the electrical system of the bike though. However, it didn't last too long. The rain, mud, abuse, and even cleaning of the bike lead to a quick demise. He ended up buying a KTM kit, and it has worked ever since.

Electrical system of the bike wont allow me even a small led bulb  (no lights anything)   so i'm kinda stuck

Obviously i'm open to all new ideas. the issue with standard fans is the amps watts they draw and you have to find them with a max of 100mm (the ones I saw draw 40 watts) they will kill the battery fast . 1 fan might be enough but i prefer running 2. I do not expect them to last very long either I'm prepared to have a faillure fast on a fan (thats another reason to have 2).

(sorry if this is messy, I'm on the app) That is all true, I would test out the battery I have, but right now im waiting on a fan that a buddy is supposed to give me. Im probably going to get a fan asap and just wire the battery straight to a fan and see how long it lasts, if its acceptable ill work from there, maybe getting a second one.

Anyone else think topic was going to be a computer guru asking questions after buying his first bike?

Oh, how weird......... I was just about to make a thread to see if anyone has installed a fan on their radiators. Cool beans.

But, how does one know if their motor is overheating though? Do you have a cylinder head temperature sensor that reads out the temp or something?

when your sitting on the trail and your bike is pissing coolant that's how you know

Anyone else think topic was going to be a computer guru asking questions after buying his first bike?

lol no but I get it he's a computer "fan"

I installed a 120mm comp fan on my exc. It's already street legal so the battery wasn't an issue. As for reliability, mine has been good. Keep in mind that I live in socal so I mostly desert ride. Wet and muddy conditions most likely would kill a comp fan fast. I used small pieces of angle aluminium on the sides of the radiator to keep the fan from resting directly on the fins. Position it to be a puller fan, (backside of rad.) not a pusher (front of rad)  Zip tie the fan in place for easy removal to replace with new fan at a cost of 5 to 8 bucks a pop. OEM rads fans for the KTM run about $130. That's at least 13 comp fans and the power draw is less than the oem fan.

 

 

Edited by pterry

(sorry if this is messy, I'm on the app) That is all true, I would test out the battery I have, but right now im waiting on a fan that a buddy is supposed to give me. Im probably going to get a fan asap and just wire the battery straight to a fan and see how long it lasts, if its acceptable ill work from there, maybe getting a second one.

Single fan   after 16h I was down to 6 volts on the battery     dual fan after a good 4 hours I was down by less then 3 volts.

I'd figure that a ''regular'' motorcycle fan drawing 30 watts   I would kill the battery in less then 2 hours

Anyone else think topic was going to be a computer guru asking questions after buying his first bike?

Actually my YZ426 is my first bike    you know 'cause suicide with knifes are for &%$#@! XD

I got a pretty good deal on it to be honest    and the only thing I had to do was this fan mod and changing the key in the countershaft gear

My uncle did the same thing on his KTM450SX-F, also due to overheating. He connected it to the electrical system of the bike though. However, it didn't last too long. The rain, mud, abuse, and even cleaning of the bike lead to a quick demise. He ended up buying a KTM kit, and it has worked ever since.

The biggest problem with the oem fan is the fact it will flatten a battery real quick. I've had a computer fan on for 4yrs now with no issues. I hit mine with a pressure cleaner too.

Most fans are rated raterproof or resistant anyway. I think vibration is more of an issue then water and dust on a fan pulling air throu the rad

This is my setup on a '07 KX450F. 2 hr run time and fan is still working fine even with pressure washing. I ended up using HVAC zip ties and drilled holes in the seat pan to secure the sealed lead acid battery. I charge it with a Battery Tender Junior through the plug sticking out of the number plate.  

 

 

 

 

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I doo like your battery setup

This is my setup on a '07 KX450F. 2 hr run time and fan is still working fine even with pressure washing. I ended up using HVAC zip ties and drilled holes in the seat pan to secure the sealed lead acid battery. I charge it with a Battery Tender Junior through the plug sticking out of the number plate.

secure DSCF3881.jpgDSCF3879.jpgDSCF3880.jpgDSCF3887.jpg

Do you remember where you got the battery and fan? I saw another thread that you posted on about this and I reall liked it.

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