EX500 fan install project - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 5 Old 08-29-2014, 09:27 PM Thread Starter
4th Gear
Join Date: Oct 2013
Location: Chilliwack, BC, Canada
Posts: 1,481
EX500 fan install project

Following the lead of someone who posted that the EX500 fan assembly could be adapted to the KLR650 (forget who this was but please let me know so I can thank the person directly). It does look as though the EX fan with shroud and mounting could be adapted to the KLR but in my case, having an intact fan, motor and shroud, I saw no need to do this.


I removed my stock cooling fan assembly:

You will notice from the photo that I use some automotive door edging to seal between the fan shroud and the radiator core. This is done for two reasons: to prevent air from entering between the radiator and the shroud which reduces the amount of air being drawn through the radiator. This is not a minor effect because the radiator core offers significant restriction to flow so it is easier for air to enter the large gap between the shroud and radiator.

The second reason is to protect the radiator in the event of the shroud or mounting developing a crack. The edging is pulled back to make it more obvious. Find some at a self serve auto wrecker. It's that soft rubber cushion which seals the door to the door frame when door is closed.

I used an old hand held wind speed gauge to try to compare flow as below. You will notice that the EX500's motor is quite a bit smaller as it only draws 3 amps even with the more effective fan.

KLR fan has 6 blades, 5-1/2" diameter fan, 0.925" wide blade, 25 degree angle. 3.7 amps at 12 volts, 25 mph wind.

EX500 8 blade, 5-3/8" diameter, 7/16" wide blade, 55 degree angle, 3 amps @ 12 volts, 28 mph wind.

I next swapped the EX500 fan onto the KLR motor in KLR shroud, 30 mph wind, 4 amp draw.

Fan assembled 14.6 volts, 30 mph+, 5.0 amps tested on bench. Much more total air flow!

With fan installed onto bike with stock wiring, 14.6 volts at battery, 12.8 volts at fan, 4.6 amps. From this one can see that the fan already moves more air but can use help by improving the wiring.

Further testing revealed the following:

Vd in the positive side battery to fan relay white wire 0.310 volts. I soldered a shunt wire from the output of the (previously installed) Main Power Relay to White wire at Fan relay plug.

Vd fan relay Blue wire to fan plug Blue wire 0.385 volts. will deal with that later.

Fan ground circuit Vd 0.48 volts- will deal with that later.

Fan now 5.1 amps with battery at 14.6 volts.

Bent back the fan motor frame sheet metal and steel basket shroud to increase rear opening size. You can see that in the earlier photo. I was tempted to snip the excess sheet metal but decided it would be safer to retain it by bending it out of the air stream.

Much more air flow! There is a real roar under there with much more air flow.

I will improve the wiring between the fan relay and fan motor, as well as the fan motor ground circuit tomorrow but already see a very significant improvement. Likely it is closer to a Gen2's larger fan but may be better, given that one cannot seal the self ducted Gen2 fan to the radiator core.

The EX500's fan blade assembly fits directly to the KLR's motor. The photos I took seemed to have disappeared onto the internet between my camera and computer.

I didn't check to see if the EX500's fan can be purchased separately.
I'm up to 87 modifications on this bike. ;-)
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post #2 of 5 Old 08-31-2014, 10:04 AM
Join Date: Aug 2014
Location: Eldorado tx
Posts: 2
Was wondering if over heating problems was the purpose of this mod or if was done to solve another issue
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post #3 of 5 Old 08-31-2014, 12:43 PM Thread Starter
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Join Date: Oct 2013
Location: Chilliwack, BC, Canada
Posts: 1,481
You didn't specify as to whether you wanted an honest answer.

Sorry, just being silly because the modification list for this bike just hit #87 which seems a bit outrageous but not yet to the 95 mods on my previous one.

I've not had over heating problems but some of the reason may be that it is not nearly as hot here as in the south, I no longer do the hard, slow trail climbing at higher altitudes so there is even less need, likely, to improve my system that for my previous bike which was used in that way. I didn't have problems with it either.

I do some modifications in order to improve the way that the bike performs for my use, as do most people, but others in order to study the effects of the change. In the case of this bike, it has a 195 F thermostat, by-pass passage similar in function to the Thermo-Bob2, clean radiator, pipe insulation foam between the left side of the radiator and the plastic side shroud, the shroud is pulled out by a tie wrap through the lower corner to rest against the HT radiator protector in the intent to improve air flow by forming a wider scoop, the fan shroud has automotive door seal rubber to seal the shroud to the radiator core in order to prevent air recirculation around the shroud. Now: EX500 fan which increases air flow, + improved wiring to further increase fan power & air flow.

Tinkering, improving as have done with the other mods. I offer the information in the hope that it may be useful to someone who has an overheating problem which is based in insufficient fan air flow.

I have not measured the heat drop between top and bottom radiator tanks but may do that at some point because it would be simple enough to remove the door edge seal, re-install the original fan, and power the fan at the original voltage level. Your question suggests to me that I should do so at some point in order to close that loop.

Not certain that this was useful but happy to try to respond as needed. Even more interested in hearing errors or omissions.

I appreciate the suggestion inherent in the question,


Originally Posted by KS2014.5 View Post
Was wondering if over heating problems was the purpose of this mod or if was done to solve another issue
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post #4 of 5 Old 09-01-2014, 12:15 AM
Join Date: Aug 2014
Location: Eldorado tx
Posts: 2
thanks for the honest answer, was just inquiring because I do live in HOT environment and just bought my first KLR was looking to head off some problems-- as for reasons behind doing projects like these... why not!!! keep the posts coming
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post #5 of 5 Old 09-01-2014, 01:15 AM Thread Starter
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Join Date: Oct 2013
Location: Chilliwack, BC, Canada
Posts: 1,481
I should have used a pair of remote thermometers such as some Ebay ones to check top and bottom radiator tank temperatures but have not done that as yet. Perhaps you might try some experiments to see how various mods go towards increasing the heat extraction (temperature lost from the coolant) between the top and bottom tanks?

I have one in the dash measuring the temperature of the air near the right fork leg, just for interest while riding, so could move that to the top tank and add another to the bottom tank in order to measure. Will see if I have both time and ambition before the temperatures start to drop going into the fall.

My bike will be off the road until about the end of the week awaiting the new header flange gasket so can't do before that and am wanting to try a new MOSFET VRR just recieved + hoping to get the brake conversion done.
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