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cooling fan

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Just purchaced a 2012 ktm 300 xc. The starter, battery and cooling fan have been removed. Will a cooling fan work (when the bike is running) if I install just a fan.

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I have built several fan systems over the years for my bikes.  Not hard to do and are fairly cheap, depending on needs.  My 300 runs 4-12v light-med duty 3.5in computer fans rated for about 45cfm/min each.  I have them connected to a small 8-cell AA battery pack holder from Radio Shack and a rocker switch on my handlebars.  Only use them for gnarly stuff or if I'm slow pokin' around with my youngest who is just learning a clutch.  This setup ran me around $20 and the AA costco batteries were installed 2yrs ago.

On my 450R, I used stronger 130cfm 4in fans (1 per radiator).  These were 5v fans and I bought a small 5v usb battery pack with remote off ebay.  That setup was a little bit more, but still around $50 IIRC.  Points to remember: bigger/stronger fans make more noise and drain batteries faster, the 12v AA battery packs are cheap to build and can be replaced at any gas station, you don't have to order the expensive KTM stuff to get the job done.  They've held up well over the years in all types of weather or riding conditions, not to mention my boy and the his liberal use of our pressure washer.  

If you use the AA batteries, there are differences between alkaline and rechargeables, first being actual cell voltage.  Most alkaline batteries that I've come across in AAA, AA, C, or D-rating are 1.5v each.  The only difference in these cells besides their size is capacity.  Being bigger, the C or D cells will last longer while producing their rated 1.5VDC.  There is a carryover effect when these batteries are placed in series (increasing voltage, amperage remains the same).  1.5 x 8 should equal 12v, but with the carryover (I know, not the technical term), the combined voltage of 8 alkaline cells is actually just over 13.6VDC.  Keep this in mind because some fans are not designed for the extra voltage and may prematurely burn out. NiCad or NiMH batteries are between 1.2-1.3v fully charged.  NiCad discharge at a linear rate, while NiMH batteries maintain voltage until the very last minute before completely discharged. You'll also need more cells if you go with a 12VDC fan and a NiCad or NiMH battery pack.  In the future, I'll probably go with a small LiPo battery pack if I can find a fan that can handle the odd voltages and can maintain the cfm rating I need. If you go this route, be sure to educate yourself of the uniqueness of LiPo......they aren't for everyone and need to be handled appropriately.

Summary: Homemade is more affordable and performs just as well. Not all batteries perform the same. My bike is better than yours because its owner knows how to keep it cool and save a buck while doing so!

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