Author Topic: Adding A Manual Fan Switch to a 4 Valve K Bike  (Read 27895 times)

Offline frankenduck

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Adding A Manual Fan Switch to a 4 Valve K Bike
« on: May 06, 2012, 12:39:41 PM »
Some people like to add a manual fan switch to their K bikes to help keep the bike's operating temperature down on hot days.  Adding a fan switch is really quite simple. The Motronic control unit triggers fan operation by grounding a blue/yellow wire that triggers the fan relay.  If you tap into that blue/yellow wire and have the switch ground that wire then the fan will come on.

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Offline sh00ter

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #1 on: June 04, 2012, 11:45:33 AM »
Does this grounding of the wire need to be done via relay or will a smallish (3a or so) switch work?  In other words is the full load of the fan going through that wire or are we just activating a relay which is then carrying the load of the fan?
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Offline frankenduck

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #2 on: June 04, 2012, 12:09:37 PM »
blue/yellow wire that triggers the fan relay.

Very small load.
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Offline sh00ter

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #3 on: June 04, 2012, 02:58:22 PM »
blue/yellow wire that triggers the fan relay.

Very small load.

SO RTFP ...  :laugh :laugh   Thanks!
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Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #4 on: July 08, 2012, 09:30:27 PM »
Does this also apply to an 85 K100RT?  My electrical box does not look like this.  The wire stated does not seem to control the fan.  I will try to post a pic tomorrow of my box.  I would like to do this mod as when it gets real hot out, my bike will shut down.

Offline frankenduck

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #5 on: July 09, 2012, 12:18:45 PM »
No, an 85 K100's fan is triggered by the white temp relay.

What you'd need to do is add a relay that sends 12V+ the violet/yellow wire to the fan.
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Offline Inge K.

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #6 on: July 09, 2012, 06:21:24 PM »
A second possibility you find at post #11 in this thread.

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Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #7 on: July 11, 2012, 08:31:01 AM »
That helps, also, when I put the violet/green wire to ground the fan comes on (as does the temp light on the dash)  But I think I'll try the +12vdc to violet/yellow.  I hope this cures my shut down when hot.

Offline frankenduck

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #8 on: July 11, 2012, 08:37:06 AM »
If your bike shuts down when it warms up then that's typically a symptom of a failing Hall Effect sensor.
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Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #9 on: July 11, 2012, 11:47:41 AM »
It only shuts down when its really warm out (85+), but then if it is let set for 5-10 min, will start and run for undertimined time.  But again only when outside temp is high.  Otherwise, no worries. :confused: :dunno

Offline frankenduck

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #10 on: July 11, 2012, 12:12:02 PM »
It only shuts down when its really warm out (85+), but then if it is let set for 5-10 min, will start and run for undertimined time.  But again only when outside temp is high.  Otherwise, no worries. :confused: :dunno

Certainly sounds like the symptoms of a failing Hall Effect sensor.  Cary some water with you (cold if possible.)  When the bike quits pour the water on the HES cover plate to cool it down.
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Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #11 on: July 11, 2012, 12:15:27 PM »
I have heard of this, will this allow the bike to restart right away?

Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #12 on: July 11, 2012, 01:35:59 PM »
Are the hall effect avaliable (ebay, else where, price?)  Found on bike bandit for $500+

Offline frankenduck

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #13 on: July 11, 2012, 02:04:55 PM »
www.kbikeparts.com (me) - search for 12111459033
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Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #14 on: July 11, 2012, 03:26:12 PM »
Running bench test;  Outside temp - 90 deg,  RPM - 2800,  Large fan blowing on Bike, ran for 40 min then shut down.  Cooled HES cover with 40 deg water til cover was cool to touch (10 min) bike will not start.  Run power to PUR/YEL wire for fan, run fan for 10 min then bike re-started.  Bike ran for 15 min then shut down.  Run fan only (no cooling HES cover w/water) for 10 min, bike re-started.  Suspect ICU overheating.  Thoughts?

Offline EJ

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #15 on: July 12, 2012, 08:47:17 AM »
Test continued:  7:30 PM,  Out side temp 77 deg,  rpm @ 2800,  large fan blowing on bike,  bike fan in normal mode,  ran for an hour w/no issues
 :dunno2: :dunno2:

Offline BexarWolf

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #16 on: July 20, 2013, 09:03:49 AM »
Just to be sure I'm splicing correctly, is this the right way to cut in a switch for the manual fan switch?

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Offline Scott_

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #17 on: July 20, 2013, 11:34:55 AM »
Looks right to me..... Go for it.
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Offline Filmcamera

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #18 on: October 03, 2016, 11:41:40 AM »
My fan is wired directly to the 87 pin on the fan relay so it is always on (it is the yellow and purple wire in the photo). 

I assume that means the whole temp circuit has been bypassed altogether.  I would like to try and get it back to how it is supposed to be and then add a manual override.  Where should I relocate that wire to put it back where it came from?

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Offline Inge K.

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #19 on: October 03, 2016, 02:00:48 PM »
I have mentioned in another thread that you have two ABS warning light relays, while you should only have
one................both of the relays you have is placed in the wrong socket.
One of them is placed in the socket for the fan relay....that's why your fan is running all the time.

The ABS warning light relay is a NC relay, while the fan relay is a NO relay.....if your bike reaches a high
enough temp (with the continously running fan) the fan gonna stop, at the point it normaly should have
started.
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Offline Filmcamera

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #20 on: October 03, 2016, 05:44:18 PM »
Inge when I replaced the blue fan relay with a yellow one as I think you had suggested all I did was blow a 15 AMP fuse...
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Offline Laitch

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #21 on: October 03, 2016, 06:18:16 PM »
Inge when I replaced the blue fan relay with a yellow one as I think you had suggested all I did was blow a 15 AMP fuse...
I think it would be helpful to post photos of the relay—the side with its identification and the side with the pins showing how you wired it.
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Offline Filmcamera

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #22 on: October 03, 2016, 06:47:43 PM »
Well I haven't actually wired anything yet - the fan is always on which was done as a mod by a mechanic just after I got it because on the first ride home when it overheated  yet the fan never came on.

 I understood from from Inge that the fan is always on  was because the blue relay in the fan slot is a normally closed relay when it should be a normally open one. That would indicate that all the mechanic did was switch one type of relay for another. So I removed the blue relay from the slot and put one of the yellow ones in its place.  As soon as I turned the key the fuse blew.

On the relays I have there is no wiring diagram but I get a resistance reading of 114,2 ohms on the yellow one when I go from pin 85 to 86 and on the blue when I get 95.9 ohms when I go from the same pins 85 and 86.

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Offline Inge K.

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #23 on: October 03, 2016, 11:56:12 PM »
Doesn't look like OEM relays, which explains a lot.....take a picture from the top also please.
Measure between 30 and 87 to determine if it's NC or NO relays.
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Offline Martin

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Re: Adding A Manual Fan Switch to a 4 Valve K Bike
« Reply #24 on: October 04, 2016, 12:04:52 AM »
HMC could refer to Honda Motor Company I've had a couple of Honda's and it looks vaguely familiar.
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