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4Strokes.com Honda Technical: XR650R Radiator Fan Installation by Andy Waddell
Page Jump Links: Cooling Fan | Fan Mounting | Drawings & Sketches | Electrical | Mounting to Bike | Fan Update
As many XR650R owners are aware, the bike comes from the factory very restricted in terms of jetting and airflow. This needs to be corrected both for proper starting, running and power of the bike, as well as to help the bike run cool. That subject has been covered well before, but there is a part of that issue that became important to my XR650R and me and also spurred the topic of this article, the addition of a cooling fan on the Honda XR650R.
I did all the modifications to my XR650R to uncork it, except one: moving the needle clip in the carburetor. Why? I guess I was reluctant to open up the top of the carb since the bike seemed to be running OK, and I knew that the o-ring on the carb cap was potentially a real pain to get back together. So, I left it alone. Well, long story short, on a ride late last year in the same conditions, same speed, same everything as two other XR650Rs, mine overheated and theirs did not. The only difference between the bikes? That needle clip position.
After thinking about it, it DOES make sense that the bike could overheat with the clip in the stock position. Sure, the pilot jet was changed to a 68s and the screw backed out. Fine for near idle. And the main jet was changed to a 172. Great for 3/4 throttle and up. However, I did not do a damn thing for the bike in the 1/8-3/4 throttle area, where I ride it most! That is where the needle clip position has the most effect. Anyway, I overheated in some tight stuff. We normally ride dual-sport where there is plenty of speed (read: airflow) to cool the bike. Well, the overheating in the tight was a real pain in the ass. Ruined my day, because even once I filled her with water from my backpack and we got out of the tight stuff and back into higher speeds where there was plenty of airflow, I never trusted the bike again for the rest of the day, and only wanted to get back to camp as soon as possible in case it got hot again. Not fun at all, especially when it is a long drive to get to that riding area, and you are only on day 1 of a 2-day ride. I am sure the other guys riding were not happy that we had to leave the tight stuff they were enjoying, either. So, the moral of the story is: move that needle clip from the stock 2nd position from the top to the richer 4th position from the top. The other two XR650Rs I was with that day have never overheated, and they have that change. (Now I do, too).
Being that it is winter in Michigan and the bike is just getting maintenance work until spring, I decided that adding a cooling fan would be pretty easy to do and pretty cheap as well, and would also give me some good insurance against overheating happening again. Even though I am sure the needle clip was the problem, for a few bucks I could have a cooling fan, too, just in case. Belt and suspenders.. why not!
XR650R Radiator Cooling Fan
I found a cooling fan at Newark Electronics online that looked like it would fill the bill. It would physically fit, would not pull much current, had good airflow, and was cheap, too! I cannot say yet how long she will last, but at only $20 total including shipping I can replace it every season if I have to! In the photo, there is a connector and wiring protector/conduit on it. I added that myself. The fan comes with 22-gauge leads.
Radiator Cooling Fan Mounting
I planned on mounting the fan on the right hand radiator, because it has tabs on it already for California bikes that have a Pulse Secondary Air Injection (PAIR) Control Valve mounted there. (I think most CA riders end up removing that valve as part of the uncorking, so these instructions should work for them, too).
PS: Note that the radiator shown in this picture and all the rest is one that is sprung a little bit from getting poked hard with a big branch; it has been replaced (you should see the front!). So, it is a little wavy looking, but you will get the idea!
Note also in the picture that one of the tabs has what is called a J-nut (shown on inset with screw) on it. This is what I used as the nut for mounting the fan bracket, as you will see later.
Radiator Cooling Fan Sub-Mount
The fan cannot mount directly to the tabs for a couple of reasons. First, the holes in the fan do not line up right (not surprising). Also, the fan needs to be mounted such that the face of it is no more than 1/8" away from the radiator itself. If you do not do this, the fan will suck air from around the edges, rather than through the radiator itself. So, we have got to make a mount for the fan that will both allow us to position it fore/aft so it is close to the radiator core, and also so it will fit the tabs. I used a material called G10 fiberglass, 1/16" thick. (I work for a hobby rocket company in the evenings, and they use G10 for the rocket fins.) Think "electronic circuit board material" and that is pretty much it.
Another consideration is that you want the mount to interfere as little as possible with the normal airflow through the radiator. You do not want a big plate back there for the air flowing through to hit against as that might restrict airflow. So, the mount needs to be as small as possible, yet strong.
I mentioned that we would have to get the fan as close as possible to the face of the radiator itself so it pulls air through the radiator instead of just around the space between the fan and the face of the radiator. I did this by using nylon spacers between the G10 bracket and the radiator tangs.
First, you need to mount the fan to the bracket. I did this using Nylok nuts; they are basically nuts that have plastic inserts that act like built-in lock washers so the nut does not move once you get it where you want it. I felt these were better in a vibrating environment like an XR650R than traditional lock washers and nuts.
You can see the nylon spacers that I was talking about for positioning the mounting plate near the face of radiator. To the right is another picture for a better idea of where we are going with this.
Now we have the cooling fan mounted to the bracket for attaching it to the radiator tabs. Here is what it should look like, in general.
Cooling Fan Electrical
Now we are ready to put the fan and bracket on the bike. I have not covered the electrical system on the bike itself, mostly because it is pretty darn simple (and because I did not take any digital pictures while I was doing it a few days ago!).
If you are considering adding a fan to your XR650R, you are fairly handy to begin with. You have had the tank off and the seat off, and you have seen how wiring is connected and routed from the front of the bike back to the under-seat area. Well, same thing with the fan wiring. My bike has a Baja Designs dual-sport kit on it, so I used the battery connections to connect the fan, but even stock bikes should be able to use the fan, though you will have to decide where and how to connect into the system. (Maybe the headlight feed? Fan takes only 4 watts, and the headlight is a lot more than that, so I think you could safely get the fan power from the headlight circuit on a no-battery bike).
Here is a quick drawing of a little jumper harness I made to be able to easily connect the new wiring into the existing bullet connectors on the XR650Rís electrical system. (I do not have a part number for the bullet connectors I used, but I am sure Radio Shack will have something that will work).
I used a Radio Shack Part No. 270-025 "2 Conductor Automotive DC Accessory Cable" to do the bike wiring. It has an inline fuse holder (I used a 5-amp fuse since the package said the harness was rated for 5 amps) and two-way connector already built in, so it was perfect, and for $2.49 it was the right price, too! (Remember, the fan is only 4 watts and comes pre-wired with only 22 gauge wire, so you do not need any honkin' thick wire to run it!). I had to add about 2 feet of wire in the middle of the Radio Shack harness to make it reach properly, but it is still a good deal at $2.49 since you get the connector and fuse holder you need anyway.
Run the wiring up to a switch and over to the right-hand radiator. Be sure to use some wiring conduit to protect the whole wiring system against rubbing. Make sure you set up the length over to the radiator area so there iís plenty of slack for the handlebars to be turned to full lock in both directions.
I used an automotive 12-volt toggle switch available at any Pep Boys, Murray's, K-Mart, etc. Nothing special here.. just a 12-volt automotive toggle switch (mine is a Calterm P/N: 41720, if you must know). I mounted my switch with a G10 piece again, using one of the handlebar mounting bolts. I would recommend a stout switch (i.e. metal), since you are probably going to be flipping it while moving, so you do not want any cheap plastic to break if you hit a bump while you are flipping it.
You may choose to use a thermoswitch (a switch that is plumbed into the cooling system, so when it sees a certain temperature it switches the circuit on), but as I mentioned, I do not necessarily know as I am going to need the fan as it is, so I am not going to get into drilling and tapping my thermostat housing for a thermoswitch just yet.
Cooling Fan Mounted to Radiator and Bike
Not a lot left to do at this point. The fan wiring/connector from the switch is down to the radiator area. Here is a photo of how the whole thing will look mounted up.
At this point there is nothing much to do but push the 3 J-nuts onto the radiator tabs, and mount the fan/bracket assembly to the radiator. Remember you need to make sure the fan is very close to the radiator core, but not touching. Mine ended up needing about 3/8" nylon spacers to do so, but you will have to test-fit and adjust yours to match what you are using.
Also, I do not have a picture of it but I put some of those little self-adhesive felt discs on the screw heads that attached the fan to the G10, where they are near the radiator. I wanted some kind of buffer between the screw head and the radiator. They will probably fall off the first time they get good and hot but they make me feel good for now that I have something protecting those screw heads from digging at the radiator if somehow they get too close.
Bolt the sucker up, connect the wiring, and tie-wrap everything in place. Put the shroud back on and you are good to go!
Hope this has helped you if you have decided that you want a radiator cooling fan on your XR650R. I do not think I will ever need it but for the 30 bucks or so it cost me, it is cheap peace of mind to know it is there!
Credits: Written by Andy Waddell and edited by 4Strokes.com
PDF version of this article: xr650r_cooling_fan.pdf
Newark Fan Update by Bryan
I installed the cooling fan from the "XR650R Radiator Fan Installation by Andy Waddell" article a couple of years ago. It got wet, (do not wash mud off in THAT location, I killed the fan!). That fan is no longer available from Newark. The replacement fan also from Newark is: SKU# 14M9058. This fan has a higher cfm rating than the one currently listed in the article. 55 cfm versus 77 cfm, and still has only a 0.48A draw. I now have the fan and a Baja Designs dual sport kit. The stock stator has no problem running high-beams, turn signals and the cooling fan. Anybody wishing to install one should know that since the Baja Designs headlight fairing is rubber mounted, the ground for the fan has to be tied into the battery ground. The positive lead can be sourced from the small running light.
Credits: Update by Bryan Simmons and edited by 4Strokes.com
4Strokes.com Technical: Honda Related