I don't have the wiring diagram, but I think there is a fan relay in the relay box.  If you put a switched bypass across the contacts, you can turn on the fan with the switch.

On my K75S I got a piece of aluminum about 1" wide and 3" long.  I put a hole for a toggle switch in one end and a hole to put it under the top fork pinch bolt on the left side.  Bend the aluminum to get the switch in a convenient place.

I Polack engineered the connections to the relay by pulling the relay out of it's socket and sticking the stripped end of the wires in the sockets and putting the relay back in.  Strip about 1/4" of the insulation off the end of the wire and twist the strands together.  Make sure all the strands go in the socket.  You don't want any loose ends causing short circuits.

lucki wrote:Is their a temp senser to active the fan, if so where is it and how to test?
I would like to have both the auto on off and a switch. How did you guys wire this?

Here's a diagram describing how the on/off switch will be wired in the temperature switching unit located in the relay box.

Located the relay. Can you use light gauge wire of the same thickness as the wire going to the relay?

Just tested fan again by jumping a2 to 15, fan works.
However when I jump from a2 to 31 to test the temp bulb on instrument cluster the temp warning light does not come on, seems unlikely a bulb, anything else?

Jump 31 to A3

31 is ground (BRN)

A3 goes to the temp warning lamp (VIO/BLK)

lucki wrote:Fan works! Did not think it would. Fan was stuck a few days ago, soaked fan shaft near blades and worked it free it became easier and spun quite free before.I put power to it.
I will put a switch in.

Is their a temp senser to active the fan, if so where is it and how to test?
I would like to have both the auto on off and a switch. How did you guys wire this?

The temp sensor on your K75S is in the stand pipe on the left side of the engine just behind the radiator.  It has two functions, one of them being the sensor that operates the fan.  To override the temp sensor and turn on the fan whenever. you like, wire a SPST switch between terminal "E" on the temp module in the relay box and ground (Duck referred to the pin as "A3" in the post above; check your temp module):

This will have the added advantage of turning on the Overheat lamp in the cluster to show you that the fine is operating.  With this setup, you have the full auto on-off capability of the temp module when the switch is off, and full manual fan control when the switch is on.

IMO there's no need to add a fan switch. If the thermo relay is operating as it should then the fan comes on when it's needed and keeps the engine within the designed operating range of below 103C and above 85C where the thermostat operates. I suppose if it's cold you can blow more heat onto your legs though.

I have read a lot of posts on this subject . When I found my fan blades seized I thought for sure it was burnt out. Just luck the bike did not call for the fan to go on when the blades could not move! As I understand this would burn the motor. The switch seemed like a good idea so the fan could be run from time to time to keep it free. So the switch goes in tomorrow. I do however appreciate all views expressed to me.

lucki wrote:I have read a lot of posts on this subject . When I found my fan blades seized I thought for sure it was burnt out. Just luck the bike did not call for the fan to go on when the blades could not move! As I understand this would burn the motor. The switch seemed like a good idea so the fan could be run from time to time to keep it free. So the switch goes in tomorrow. I do however appreciate all views expressed to me.

As shown by K bike fans that "atrophy" from lack of use, a K bike doesn't really "need" a fan. As long as the bike is moving the fan never comes on. For example, back in 2019 I brought a K1100LT back from the dead. I forgot to test the fan. It wasn't until several thousand miles of riding before I even knew it when I got stuck stopped in construction traffic in 90+ weather and the temp warning light came on. I just hit the kill switch and restarted the bike when I could get moving again.  Didn't worry about it. It wasn't until a couple of thousand miles later when I got home that I bothered to replace it with a SPAL fan. And that's on a K1100 that generates more heat than a K75. It does have slightly bigger radiator than a K75 but not by much.

If you're not in stop-n-go or stopped traffic in hot weather then a dead fan isn't that big of a deal.

Duck
Not knowing sqat about how these bikes behave you are probably right. I am thrilled by the idea that the fan will blow hot air over my old arthritic legs!
Still testing trying to get the temp warning light to work.
New battery on the way. With the bike running on the work bench I was able to run it through all 5 years that's good.

lucki wrote:New battery on the way. With the bike running on the work bench I was able to run it through all 5 years that's good.

When you ran through the gears did you notice any looseness in the shifter?  The feel of the shift lever is normally nice and positive.  If there is more than an inch of free play at the end of the shifter it indicates that the grub screw that holds the linkage to the shaft is getting loose and will need to be tightened.  It's not an emergency, but makes the riding experience a little nicer, and will help prevent false neutrals.

Temp warning light works, much maligned fan switch in and working.
Was pleased how it shifted .up and down. Just waiting for battery before I give it a road test.

I did not malign the fan switch, just gave my opinion that it is not really necessary.

Add half of a 50g tube of LiquiMoly 2019 gear oil additive to the transmission for smoother shifting.

Duck
Just having a little fun. I was going to forget the switch until you mentioned the heat on the legs! The coldest I have been has been on a bike. It does blow nice.

Found this in the tail light storage. Are the any giod? Anyone used one?

Tire inflater kit for tire repair.  Except for the package it looks to be in good shape. 

I have never used them so can't comment on how effective it may be.

Besides the inflator I'm finding lots of stuff that tells little stories.I

The fairing belly pan was painted black to cover a fiberglass patch.

When mounting the front tire inside the run was written , 92 k75rt so maybe a crash but shocks look okay. 

When changing the brake fluid has to use a heat gun to remove screws. Once inside the rubber #4 was 1/3 it's original size, took forever to bleed the bits out.I

But all in all I am happy with the bike, starts, run, idles great.

Got tires the other day, front okay, they sent wrong rear, be in Tues. Should give it a bit of a road test mid week.

Sure like the blue colour, waxed up well.

Forgot to ask. Left #4 out when done with fluid cbange. Problem?

Yes. 

Just undo the three screws and refit it.

Any on line sources for parts that you guys use? Nearest dealer to me about 60 miles.

lucki wrote:Nearest dealer to me about 60 miles.

The nearest dealer to me is 25 miles away. I buy o-rings and crush washers from him just to keep him in the loop, but the one from which I buy most of my Brick's parts is 172 miles away. That is MAX BMW. Another is Motobins in Surfleet, UK and there is a reliable private vendor in Michigan who has helped me out a few times. eBay can be a friend but using it sometime requires fully-committed engagement with scary 21st Century technology, like PayPal. 

lucki wrote:Once inside the rubber #4 was 1/3 it's original size, took forever to bleed the bits out.

You should replace that diaphragm soon. It reduces the amount of space in the reservoir for infiltration of moist air and reduces agitation of the brake fluid when riding.

Yikes just ordered the boot from bmw dealer in canada! 43.09 tax and shipping. Will price this part from sites in the US. Will make a list of stuff needed, go to the US often. If out of state no tax and often free shipping, before tax and shipping boot was 21 cdn. Live and !earn.

Try https://www.motobins.co.uk/

Checked out motobins in uk. Say on a 10US part what's your estimate for taxes and shipping from UK? Also looked at max site, registered there.

lucki wrote:Checked out motobins in uk. Say on a 10US part what's your estimate for taxes and shipping from UK? Also looked at max site, registered there.

They use Royal Mail 1st Class (under a certain weight) which doesn't cost a lot and usually gets to me in the US in a week-ish. No VAT or US taxes.

Take a look at A&S BMW too. They do free shipping on ConUS orders. Don't know how much shipping to Canada would be.

duck wrote:I did not malign the fan switch, just gave my opinion that it is not really necessary.

Add half of a 50g tube of LiquiMoly 2019 gear oil additive to the transmission for smoother shifting.

In our climate the fan can end up unused.....until you need it.

It needs to be run occasionally, otherwise it seizes from lack of use. I have quite happily run K bikes without fans for years but hotter climate needs it working. I have some of mine wired manually too and would recommend it if you live where the sun dont shine enough to give it a regular workout. I have replaced a few fans too, in each case seizure from lack of use was the issue.

92KK 84WW Olaf wrote:

duck wrote:I did not malign the fan switch, just gave my opinion that it is not really necessary.

Add half of a 50g tube of LiquiMoly 2019 gear oil additive to the transmission for smoother shifting.

In our climate the fan can end up unused.....until you need it.

It needs to be run occasionally, otherwise it seizes from lack of use. I have quite happily run K bikes without fans for years but hotter climate needs it working. I have some of mine wired manually too and would recommend it if you live where the sun dont shine enough to give it a regular workout. I have replaced a few fans too, in each case seizure from lack of use was the issue.

I've run in hot weather for long distances with a non-working fan. It's not a big deal. Just hit the kill switch when stopped and restart when you need to get moving again. The only time you actually NEED a fan is in superslow stop-n-go traffic. That's why it's not worth it TO ME to add a fan switch.

lucki wrote:Checked out motobins in uk. Say on a 10US part what's your estimate for taxes and shipping from UK? Also looked at max site, registered there.

Attached is what a brake reservoir bellows costs from MotobinsUK, according to its shopping basket software. You can calculate Canadian tax using this site. This information is easily acquired. Not a whole lot different from your Canadian price quote.

Latch
Thanks for the extra effort on this. Looks like maxbmw is my best bet while in the US.
Just waiting on new rear tire then 'll give it run down the road!

Changed fuel filter today. Last done 2015! Interesting stuff. Old bmw filter hard to blow thru.hose clamp exiting filter loose, hose clamp at pump loose. Filler cap on wrong . 180 degrees out, overflow plugged, sucked out 2 tablespoons of crud from low point in tank.I
How did it run?

Sounds like you're getting some good stuff done!

Say, is there any way you can tell if the pump is original? The reason I ask is finding the hose clamp loose coming out of the pump I can't imagine the factory doing that.

It should be a 13mm hose clamp:


The top of the OEM fuel pump looks like this:


It also has BOSCH and some numbers stamped into the side of it but you have to take it out of the rubber vibration collar to see that.

Took a close look, identical to your picture. If mine is original being a 1987 and having 122000 km on it is it on borrowed time. No idea how long these last.

They last as long as they last. Not a part that's particularly known for failure unless it sits for an extended period in ethanol gas that pulls in water from the atmosphere and when the water settles to the bottom of the tank it rusts the innards of the fuel pump.

If it's running now then don't worry about it.

Now I know what all the fuss is about! Took the bike for an 80km run today. I see now why folks like these bikes for the highway runs, cruised along nice at 110 to 120 kmph. got it on the centre stand now to check for leaks.
Trying blue devil sealer in oil some Lucas fuel injector cleaner in fresh gas.
Once again I would like to express my thanks to those that helped me and to those that someday will.

How did you make out with the rear shock?  Were you able to get it rebuilt?

Point
I hate to say this but. No the chap that promised to do it didn't - yet.
Modified a 64 buck cheapie from china, not in the ditch yet. Will get progressive or yss when in the state's.

found out my fan did not work when it started spiting boiling water out of the header tank , engine was undamaged and i now fit a over ride switch .