Today was the day I was to replace the non operating fan on my 1985 K100RS.  Alas, I've run up against a wall. I thought the fan could be replaced by working from the backside of the radiator.  However, I can't access the screws that secure the fan to the radiator.  I cannot get to the lower left one, and the upper one I can't even see, much less touch. 
Now, the obvious question: Is it necessary to pull the radiator out (from the front of the bike) to remove the fan and install the Spal fan, or is there some secret that would allow me to do this working from the rear side of the radiator?
As you may imagine, I'm not keen on pulling the fairing bits off.  They are not fun to line up to re-install. The last time I did that I ended up breaking one of the mounting tabs
I'm always taken back by those here to offer the off hand comment that these K-bikes are easy to work on.  Even pulling the air box off a 1985 K-100RS will have me running through my vocabulary of not-too-polite words!

Just did the Spal retrofit on my RS.  Yes, you do have to pull the radiator and all the surrounding tupperware to do it.  My secret is to leave every screw as loose as possible until they are ALL started before tightening any of them.

I park the bike on a piece of carpet, and wear some old clothes that I don't mind rolling around in and then get comfortable laying under the bike.  It's the only way I can get all those darn screws around the forks and the radiator started. 

Turn the radio way up so no one can hear you cussing.

brickrider wrote:
I'm always taken back by those here to offer the off hand comment that these K-bikes are easy to work on.  Even pulling the air box off a 1985 K-100RS will have me running through my vocabulary of not-too-polite words!

Brickrider - I hear your pain, but all things are relative. Removing the fairing (certainly the lower sections and the radiator cowl) is not technically challenging but sadly it can be fiddly getting it reassembled (aka PITA at times). As it needs to come off for many jobs, practice does make perfect - eventually! As point75 says, getting all screws/bolts started before tightening any of them is sound advice. I use the positive mental attitude of "if it takes me 1 - 2 hours just to remove and replace the fairing, that is a whole lot of money saved in labour costs by not getting a "professional" to do the job for me". I could happily skin my knuckles and cuss all day long if I think I am saving serious dough in the process. Also, there is no guarantee that the "professional" actually is familiar with the K bike and doesn't go and break something - for which you'd be billed (cos its old and the plastic is all brittle and other such BS).

I had my latest acquisition (Gretel) in pieces yesterday to fit GPS mount and electrics, fit an over ride switch on the fan and, while I was in there, deoxit all electrical connectors under the fuel tank and clean/tighten the main earth point. The philosophy being - while the fairing and tank are off...what else can I do that will stop me having to repeat the performance all over again in the near future. 

AFAIK, the only way to get to replace the fan, is to remove the radiator from the bike. I have done this job (when trying to get to the water temperature sensor on the inside of the bottom left stub) and it does take a bit of patience. So in addition to removing the lower fairing and radiator cowl, you need to drain the coolant (which implies the fuel tank has to come off in order to refill the radiator later on) and remove the cooling hoses. There is a pesky allen screw bolt at the top front of the radiator which is a PITA - it took me a while to find it as it is hidden under the mounting rubber along the top of the radiator. You also need to unplug the fan from the wiring loom as it is too short to extract the radiator with it still plugged in. Once all that is done...the radiator simply tips forwards and lifts out. You then have full access to the old fan (at which point you test it on a direct 12v supply and find that it does work after all and wasn't the problem!!!!!! While you are in there, it is worth cleaning up the water temperature sensor and electrical connection. But technically - none of this is difficult and well within the capabilities of the home mechanic

Remember, every hour spent is an hours labour cost saved - yesterday, I saved myself a fortune doing stuff at the front end of Gretel. Today, I am going to save even more by doing jobs at the back end (Gear Position Sensor clean up - it's being erratic) - no fairing to come off, but needs the swing arm removing...so while I'm in there, standby to grease the splines. Do one job, get one job for free!

It's a labour of love. 

"It's a labor of love."

I am reminded of a friend I knew a long time ago when I rode enduros who told me that maintenance wasn't work so much as it was foreplay for Sunday's race, and that the successful guys looked at it that way.

Since most shops charge using the flat rate manual which inflates the time estimate, I usually figure my time at around $85-100 per hour.  It's pretty easy to save upwards of $1000 in a single weekend of tinkering about with my bikes. 

I shudder to think what the work I do in the winter would cost me at the dealer.  And that doesn't even factor in the parts I'm using off of eBay.

Wise words of encouragement guys.  Thanks.  A new day, a new resolve.  I'm set to remove all the plastic and pull the radiator out the front.  Yesterday I serviced all the stuff under the tank and behind the radiator, so today could be a less frustrating 6-8 hours. 
I continue to be amazed at how tight everything is sandwiched in there.  I'm thinking now of the lack of room to do something as simple as disconnect the wires from the fan.  One really needs tiny hands at times.
I completely agree and understand the advantage of keeping in mind all the money saved by doing such work personally.  When I first bought this motorcycle, I thought I'd be thrifty and have a mechanic who, though certified, worked out of his home, do the install of the temperature gauge. Big mistake!  I nearly fell over when he presented the bill for his services.

Hi,I am also experiencing fan problems.I have pulled it all apart and the brushes were fried.I have ordered a used fan from eBay.
Whilst I have got it all apart I have decided to fit a manual over ride switch.On the fan side of the fan relay I have fitted a switch to the blue and yellow wire connected to earth.This gives me 12v at the connector plug for the fan when the ignition is on.Will this interfear with anything else and will the fan still cut in automatically when the correct temperature is reached.

Thanks badger100.

You want to attach a SPST switch between terminal "E" (Purple/Green) on the temperature relay and ground as in this diagram:


I don't see a blue wire on the temperature relay in the schematic; don't know where you've attached this switch. Blue with tracer wires on the bike are generally power wires, which means you might be creating a beautiful short to ground.

I'm pleased I installed the Spal fan instead of the OEM cooling fan!  The intervening years have brought along fan development.  The Spal is quiet, powerful and it's considerably smaller that the OEM version.  Of course, beginning  a project on an old machine invariably leads to "as long as I'm in here" moments, and this was no different.  I cleaned up a good number of electrical connectors and a bit of grunge I found on the engine case where the light doesn't shine.  I treated the grill over the radiator to a fresh coat of paint too.
The job took far longer than I ever imagined it would, even understanding my modest shade tree mechanic skills I think I wrestled with the front section of fairing a good 2 hours before I finally persuaded the bits to line up and accept the fasteners! I had to walk away twice for a break to avoid becoming the owner of a naked bike.
Now, the job is finished; the old girl passed the road test with honors and I'm a happy rider again.
Now, what to do with those "extra" bits I have left over? 

You should always keep those extra bits because you will need them next time and will need the container for the other extra bits left over.

badger100 wrote:On the fan side of the fan relay I have fitted a switch to the blue and yellow wire connected to earth.This gives me 12v at the connector plug for the fan when the ignition is on.Will this interfear with anything else and will the fan still cut in automatically when the correct temperature is reached.

From the avatar it looks like you have a 16V...and it's safe to ground the
blue/yellow wire between the negative side of the fan relay coil and the
Motronic unit. The fan gonna function as normal when the switch is off.

Thanks Inge,I thought it was OK on the 16v rs.I have zip tied an old 12v computer fan as as temp measure.Until my replacement arrives.It would be interesting to see how it copes.I think two of these wired in parallel could be an awfully cheap fix worth future thought.

Inge K. wrote:From the avatar it looks like you have a 16V

I wouldn't have picked up on that detail. I saw the Badger100 in the sig and thought it was a K100.