BMW K bikes (Bricks)

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Viper357

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Hey fellow brickers

Please excuse if this is a really newbie question but exactly how does one install a manual switch for the cooling fan to come on? I have a K100RS

I have a bit of experience in mechanical wrenching but electrics are a bit of a mystery to me

Any easy to read diagrams or tips would be greatly appreciated

Cheers
Gary


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1985 BMW K100RS
    

RicK G

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Connect a switch between terminal 15 green/brown wire and terminal A2 violet/yellow wire on the temperature switching unit.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

Viper357

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Thanks Rick

As I said I am easily confused by electrics............................ lol!


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1985 BMW K100RS
    

brickrider2

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Please excuse me if this is an obvious/stupid question. Why is a manual switch needed?

    

Viper357

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hi brickrider2

Not really needed at this stage - I was just inquiring about the switch as here in Australia , particularly in the outback areas, it can get over 42deg C in summer.

I was considering a round Australia sometime in the future and I thought a manual switch would be of some help reducing the heat etc etc

Where I live in Tasmania is the most southern state and as such there is no need - its nice to have the warmth from the motor lol!

cheers
gary


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1985 BMW K100RS
    

indian036

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brickrider2 wrote:Please excuse me if this is an obvious/stupid question. Why is a manual switch needed?
Theoretically, it shouldn't be needed.

When I bought my bike the fan motor was fried. I put in a manual switch while I had it apart so I could check that it was still operating, rather than let it get gunked up bearings without me being aware of it, and getting fried again.
It could also be used as a pre-emptive strike to slow the temperature getting to normal fan trigger temp. Could be handy if I were riding today at high 30s temps. Not strictly a 'need', though.

Bill


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1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

K75cster

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Yep around 38ish here at present, a mild westerly fanning the fire across the valley floor, Good to see the Summer heat start to dissipate hey.


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

Born Again Eccentric

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I fitted a fan over ride switch to both my LTs - not because we get anything like those kind of temperatures in the UK, but it doesn't take much for the fan to start kicking in when caught in slow moving city traffic and I have had problems in the past where the fan didn't kick in when it needed to and I suffered a boil over.

Just a thought though, particularly for those riding regularly in high ambient temperatures, is the fan motor continuously rated? By that I mean, is it designed to run continuously for long periods of time? I have noted from previous fan posts that many fan fails are associated with the plastic melting in the vicinity of the brushes - is this due to too many start stop cycles (with the fan frequently cutting in and out) or is it due to prolonged running (switched on and stays on). Depending on the answer, a fan over ride could be friend or foe. As I understand it, and as explained by Duck on a recent thermostat question post, the engine gets all the cooling it needs due to the air flow over the radiator while moving at a decent speed (the necessary speed is not that high either, in my experience). The fan just provides the air flow when the bike speed is very low and/or the temperature is high.



Last edited by Born Again Eccentric on Thu Feb 25, 2016 7:14 am; edited 1 time in total (Reason for editing : spell autocorrect is not my friend!)


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Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

duck

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And if you want to know what you're doing when you install the switch:

Grn/Brn comes from the #7 radiator fuse

Vio/Yel is 12V+ power to the fan


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Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

indian036

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Born Again Eccentric wrote:
Just a thought though, particularly for those riding regularly in high ambient temperatures, is the fan motor continuously rated? By that I mean, is it designed to run continuously for long periods of time? I have noted from previous fan posts that many fan fails are associated with the plastic melting in the vicinity of the brushes - is this due to too many start stop cycles (with the fan frequently cutting in and out) or is it due to prolonged running (switched on and stays on).
Melted plastic brush mounts was the obvious problem with my fried fan, but in addition the bearings were not allowing rotation.
While I have no proof that this was the reason, a non-rotating armature means that the significantly higher current required briefly to start an electric motor, (normally reducing to a fraction of that when it is running,) would be the constant current level. The heat induced by that, combined with no airflow cooling from the fan would melt the brush mounts.
Based on that theory, I run mine from the switch occasionally to keep the bearings free. It hasn't happened yet, but if I hear the fan running more slowly than usual I will lubricate the bearings.

I don't think it is due to stop starting or prolonged running. I would be very surprised if the motor was not rated for continuous running.

Bill


__________________________________________________
1985 K100RT Red. VIN 0028991K100RT ENG 104EA248523386
1985 K100RT Blue. VIN 0029036K100RT ENG 104EA25852071
1990 K100LT Black. VIN WB105060310190452
1984 K100RT White. VIN. 0023022K100RT ENG 104EA32848523
    

robmack

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The fan motor is rated for a continuous duty cycle. It's not under a very large load so the size of the motor is adequate. What causes the burnt brushes is stalling due to bearing seizure, as mentioned above.


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

Holister

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I think the only reason you'd want a fan switch is to be able to switch it on in stop/go/slow traffic and probably a good idea to install an LED to remind you its on. I would imagine the bearings and brushes would wear out much quicker if left on needlessly for long periods.

In high ambient temps, my feeling is that the fan won't provide any more air movement than you'd get from travelling at speed. Just because the fan may cut in while you're travelling along doesn't mean you're getting extra air movement and extra cooling. When the force of air from travelling at speed (i'm guessing 40 or 50 klm) exceeds the amount of air the fan can move, the fan becomes redundant whether it switches on or not.
If the fan comes on while you're travelling at speed then it could mean a couple of things....
- The ambient air temp is really high and the radiator cooling is not as efficient.
- Your engine is overheating possibly due to running lean (air mixture/leaks etc), valve clearances etc. Oil plays a big part in cooling the engine as well. Old oil or a clogged filter will hinder oil cooling.

I've been seriously considering looking at fitting an oil cooler this winter. Summer temps seem to be getting hotter and hotter here in Oz lately.


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

brickrider2

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It wouldn't surprise me to learn the temps are rising, Kap'in. The scientific community has been sounding the alarm for some time. Locally, our hottest part of the year is August when we often see a number of days that exceed 100 degrees f. Despite being developed in a rather cool climate, I think BMW did a good job sizing the K-bike's cooling system in general. Okay, the fan motor must have been the idea of the bean counters, but....
With my after market Spal fan in stop and go traffic, the needle of the thermometer begins to drop within seconds of the fan cycling on. It's a welcome sight to see on a hot day! cheers

    

Viper357

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Thanks everyone for the tips and advice

fantastic to have discussions like these on forums - I am always grateful for any advice I can get

If anyone is coming to Tassie anytime just let me know and a warm welcome will be definitely in order


cheers
gary


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1985 BMW K100RS
    

Born Again Eccentric

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Hey Viper, there's a gathering in the making in April....don't think I can get to Tassie this time around, but if you could get north....it'd be a great chance to meet some of the krew from home and away.


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Paul

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurancewrite-off rebuild Feb 17
"Donor" K100LT 1990 (Red) (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike). June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

Viper357

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Thanks born again eccentric 🆒

Can you give me some details just in case I can get away for a few days???


cheers
gary


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Holister

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Northern Visitor inbound - Sydney:16 - 22 Apr 16

Gary, If you view the Latest Topics on the Portal tab you'll see ALL posts in order as they are posted to the forum... easy.
The Forum tab categorises posts and you then you need to look around to find new posts in each category... easy to miss something.

If you make it to the mainland with your K let us know.... any excuse for a meet-up and ride.
Maybe you could pencil in next year's Snowy Mountains Run.

Cheers



Last edited by Kaptain Holister on Sun Feb 28, 2016 6:34 am; edited 1 time in total


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

Viper357

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Thanks Kaptain I will have a look


cheers
Gary


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1985 BMW K100RS
    

Rabidchiwawa007

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Personally, I run a manual fan switch on mine because the computer stopped sending ground signal to turn on the fan at the appropriate temperature. I like the control, really. And, of course, since it's a K engine, even on the coldest days, you feel the heat and wonder why its so hot all of a sudden as soon as the heat gauge gets to the half way mark (aka, before anything bad is even close to happening).


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1968 BSA Lightning
1991 BMW K100RS 16v with K1100LT fairing
    

charlie99

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yep another manual switch user here

works a treat

as I said one time ...no way am I heading off into the hills without ensuring that thing is working properly ...or even to work ....grin

recon the exercise keeps it moving all proper like ....grin


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

Gaz

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While people are thinking about our radiator fans can I pose a question?

Has anyone ever set up a Go Pro or similar movie camera to video the fan movement when riding? I am curious to know at what road speed does the air flow spin the fan blade (if at all) when the fan is not powered.

The reason for this curiosity is that I have heard a number of people state that the reason for a manual switch is to force some fan movement every now and then to help make sure the bearings (bushes) in the fan motor don't seize up from lack of movement.

Just thinking out loud!

Cheers


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Gaz
95 K1100LT 0232224; 90 K75 6427509; 87 R80G/S PD 6292136
    

Holister

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In this heat my fan is getting plenty of exercise GazLaughing
I had a look today to see where I could fix the sport camera to get a clear shot of the fan but I'm thinking it may be too hot for it so I'm going to have a go at rigging the end of the borescope in there tomorrow and run it back to my tablet in the pannier.


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1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

Gaz

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That's a good idea Kaptain. Hope we can learn something from this.

Thanks


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Gaz
95 K1100LT 0232224; 90 K75 6427509; 87 R80G/S PD 6292136
    

charlie99

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gaz ... id have a guess that little movement til up around the 40 kph mark

nature is an amazing thing .. and some good engineering science has let us appreciate riding things that would normally get super hot ..real quick

but to the question at hand ....old gerty had a near seized fan ..(well I could turn it ...if I used a stick ) .and no there was no rotation at speed on this one, just not enough torque was achieved with the air gap between the blades.....just to lossy ...this could be desirable

consider the fan at riding speed ...even if its rotating ...it is acting as a brake rather than an enhancement ...to air passing through the radiator ...

but for me id much rather know the fan is working before I go up that hill, that starts ...about 70 ks away ...and no phone reception at all ....and know I should get home before dark ...not sitting on the side of the road waiting for her to cool down andfurry grasshoppers about to take over the roads

idle at start ...switch on ...it works ...go for a ride.... if it doesn't ...roll back in the awning and cover on .


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

Holister

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Kaptain Holister wrote:In this heat my fan is getting plenty of exercise GazLaughing
I had a look today to see where I could fix the sport camera to get a clear shot of the fan but I'm thinking it may be too hot for it so I'm going to have a go at rigging the end of the borescope in there tomorrow and run it back to my tablet in the pannier.
The video is not worth posting so I'll just report. The fan did not move much at all. At around 70kph the blades were moving a few cm and then stop. Checking my fan after with a finger I find it doesn't spin freely, so quite possibly the bearings are dry/gummed up/wearing out. I got the impression that it wanted to spin so I'd say a newish fan would and probably at a reasonably low speed.
Cheers


__________________________________________________
1988 K100RT VIN No. 0094680
1989 K100RT VIN No. 0097367 (naked)
1996 K1100RS VIN No. 0451808
Fuel: 95 Octane
Engine Oil:Nulon Full Synthetic 15W50
Gear Box Oil: Nulon Synthetic 75W90
    

Gaz

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Thanks for the feedback Kaptain.

From memory when I replaced the fan motor on my K75 those little motors only have a bronze bush rather than a rolling element bearing so next time you have a chance to get at it a good flush around those bushes with WD40 or similar might free it up nicely for you.

Cheers


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Gaz
95 K1100LT 0232224; 90 K75 6427509; 87 R80G/S PD 6292136
    

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