My bike:
1992 CBR 600 F2
D&D slip on exhaust
Jetted carbs
K&N Air filter
-1 in front / stock rear sprocket
28K miles
So I do a lot of inner city riding and the bike runs hot. It does not over heat or run in the red, but it seems to sit about 7/8 the way up the temp gauge, which is at the point that the fan kicks on. A little to hot for my liking. I went though the cooling system, but it was pretty damn clean (except the water pump fins looked a little crappy). I pulled the thermostat out and dropped it in 180 degree pot of water. It didn't open till about 196 degrees. So The stat may be a little on the stiff side. I rode (in town) without the stat and the needle still sat 7/8 up the temp gauge. Arg!!
Just adding a switch to the stock fan just seemed to easy. So I thought I would go my own route.
I have a 1990 F1 in my shop with a blown motor (rod though the block) Its been sitting for a few years waiting for a motor to swing my way
At any rate, I took the cooling fan off that bike and added it to my 92 F2.
I put that fan in front of the radiator and reversed the polarity so that it would suck in air from the front and shoot it at the radiator and motor. No since in fighting natural air flow when the bike is moving!! I hard wired it up so that when the key is on, the 2nd fan is on as well. Not really knowing what kind of draw it has on the electrical system, I wanted to have an on/off switch. Then I started thinking about the possibility of the two fans having different CFM (cubit feet a minute - amount of air that the fan moves) Which is not a big deal, except that the fan with the higher CFM will be bogged down by the fan with the lower CFM when they are both running at the same time. Which again, it does not really matter, but whats the point of having both fans run at once? It does not move more air, it only doubles the electrical load on the bike. So being the electrical geek I am, I decided to toss in a relay. I wanted the 2nd (salvaged) fan to run all the time, EXCEPT when the stock fan kicks on, plus I wanted the 2nd fan to also be controlled by a manual on/off switch.
Don't do this unless you know what your doing!! And don't come crying to me if you fry your electrical system. And as with all things on the net, your mile may vary. Not responsible for stupidity.. yadda... yadda.
YOU WILL HAVE TO MANIPULATE YOUR FRONT BRAKE LINES SO THAT THEY DO NOT TOUCH THE FAN!!!!!!!! I chose to use zip ties to hold them to the bottom of the triple tree in a way that will not restrict the travel of the front fork suspension, and will keep the from rubbing the fan blade when turning the wheel. This took a lot of checking and double checking. MAKE SURE YOU LEAVE PLENTY OF PLAY IN THE LINE FOR SUSPENSION TRAVEL AND ENOUGH SLACK THAT THEY DO NOT GET PULLED ON WHEN TURNING THE WHEEL!!! This is the most important step. You mess this one up and you may rub a hole in the break line if they touch the fan. If they are to restricted you may not be able to turn, or if your suspension travels more than what the brake line allows it will break something.
In general, I do not know the long term affects this may have on the bike!!!
You will need a 5 post relay to do this correctly. A 4 post will work but not recommended and DOES NOT follow the same instructions as below!!! So forget I even said 4 post!
Also, if you want the 2nd fan to be controlled by a manual switch, well... you will need one of those as well. This can be added later, but if your gunna do it, do it right the first time.
And, if you would like, you can include to add another "goober" to your bike. A led light to tell you when your stock fan is running. ~ Why? I don't know, but it is an option
I am going to write this all out as I don't have the time for graphics or pictures right now (later tonight or tomorrow maybe)
There is a thermostatic switch that controls the stock fan. This wire is a ground (-) wire. When the thermostatic switch gets hot enough, it grounds itself out on the radiator and closes the stock fan circuit and the fan kicks on. Splice (a.k.a. Tap into) that wire and run it to the 85 post on the relay. Spice into the HOT (+) wire of the stock fan and run that to your manual fan switch. This is the switch that you want to control when the fan is on or off manually. Now run a wire from the other side of your switch to the 30 AND 86 post of the relay. Now doing this will run a few amps through your switch, but most 12v switches will handle the draw. Take post 87a and run it to the hot (+) wire of your 2nd fan. If you opt to add that led to tell you when your stock fan kicks on, run the (-) side of the led to any ground on your bike, then run the (+) side of the led to the 87 post of the relay. And dont forget to ground your 2nd fan. I chose to ground it where there is a wire "bracket" that loops round the horn/blinker wire harness. There is a bolt that holds that "bracket" to a metal bar that spans the width of the front end, that is what I used.
That is all it takes!!
For those of you who don't want to run the amperage though your manual switch. Take the hot (+) stock fan wire and tap it into post 30 of the relay. Find any hot wire on your bike and run it to your switch. Your switch will not create a noticeably draw, so it can be tapped into just about anywhere. Run the other side of the switch to post 86. The reason I chose to jump the 30 and 86 post together is to keep all this on the same stock fan circuit, which is protected with the 15 amp fuse in the the little fuse box. Doing this will eliminate problems down the road if any should occur in the electrical system. I know that all my wiring is on the stock fan circuit and does not affect anything other than the fan circuit.
In regards to mounting the second fan. I got mine from my '90 F1. It has 3 bolt holes on the outside of the shroud. This made it easy to zip strap to the plastic "grill" in front of the stock F2 radiator. This is only a temporary thing. When time permits, I will take that plastic grill off, cut the center out a little bit so that the 2nd fan can sit flush with the radiator. Having it on the outside of the grill allows air to escape and not do its job.
Just a little recap; maybe easier to understand than the above:
Relay Post #
30 = (+) FROM hot (+) stock fan wire
86 = (+) FROM the manual switch
87a = (+) TO 2nd fan positive wire
87 = (+) TO LED if you want to know when your stock fan is on
85 = (-) FROM stock thermostatic switch on radiator
Ground the LED and the 2nd fan
Wonder how it all works?
What is happening is that the thermostatic switch is neither positive or negative in its normal state. Once the radiator fluid gets hot it trips the thermostatic switch and grounds it out. This makes that wire turn into a ground wire. With your manual fan switch ON, it supplies hot juice to the relay. When the relay has both power (86) and ground (85) it trips and connects (30) with (87). When the relay does not have power (also called "natural state") its default is to connect (30) to (87a). The reason I used a 5 post relay is so that the 2nd fan will run when the relay is in its natural state. When the relay is juiced it shuts the 2nd fan off. As soon as the stock fan is done running, the relay will be unjuiced and return to its natural state and the 2nd fan will come back on, of course, unless the manual switch is turned off.
I will make a wiring diagram and post it later.
[how to] Add a second fan
Linear Mode
