Wires cut by mouse? What are these for

[gard]

Digging into a cooling fan issue on 85K100RT, I disconnected the wires to the temperature sensor, resistance of both is about as expected. I tugged on the wiring harness a little from the left side of the bike.  There are 2 cables each with 2 wires that exit the end of the harness that feeds the fuel injectors. One of the cables goes to the temperature sensor, the other appears to cut off, one of the wires is hot. I can not see where it goes, it was sort of tucked up next to the radiator. Not sure I got the photo attach to work. I am going to pull the tank off and continue the fan troubleshooting but this cut off wire has me a little worried.

[Laitch]

This diagram is from the Clymer manual. It's labeled for K100RS 1985–1988. Check for continuity. The coolant temperature sensor itself is grounded by its threaded connection.

[gard]

Thanks. I will make sure I have the correct resistance at both the L-Jetronic connector and the temperature switch before it goes back together.  I got to the temperature switch in the relay box and applied 12V to the A2 connector wire that leads to the fan. It draws about 15A and the fan does not move.  If I poke at the fan blade with a long screwdriver it turns pretty stiffly so pretty sure its bad, I need to figure how to remove it and source a replacement. Also need to replace some fuel lines. I always wonder if this is the time to jack up the seat and replace the rest of the bike. 142k miles

Any idea what the spare wire is that is near the temperature sensor? I stripped back the insulation a little. I guess I will just tape up the end and try to forget about it LOL. The picture I attached is also from the Clymer book but they don't say what the connectors go to.

[Laitch]

If I poke at the fan blade with a long screwdriver it turns pretty stiffly so pretty sure its bad, I need to figure how to remove it and source a replacement.

Any idea what the spare wire is that is near the temperature sensor?  The picture I attached is also from the Clymer book but they don't say what the connectors go to.

Take off the radiator to remove the fan. Do a search on the site for Spal 6.5" puller fan. Here, for example, site member frankenduck, who is a semi-bonafide Adr-ninistrator, gives a cordial lecture on what's up with that. The Spal is much sturdier than the OEM fan.

When posting photos of wires for identification, clean off the wires and take a closeup photo so viewers can determine if the wires have a stripe or are one solid color. A color-coded wiring diagram would be helpful to you.
From this distance it looks like the choke switch wire colored violet/white and a ground wire colored brown. Post a new photo.

From Clymer:


The picture from Clymer is not an instructional diagram. It is used in BMW's parts fiche by vendors to help clients identify parts for sale by BMW part numbers.
From the parts fiche:


I use Max BMW's parts fiche. Delivery time of parts in stock to Vermont is a usually just a few days.

[daveson]

If you agree that one of those wires is brown and the other one is violet with a grey stripe, that's for the vacuum switch. You can run without it but you want to make sure that the vacuum hose is blocked. A lot of people disconnect it, but I can't see an advantage in doing that. The vacuum switch is next to the fuel rail, unless it's been removed. I'm guessing your brick is the earlier model, which for example has the earlier fashion foot peg plates, and the vacuum switch.

[frankenduck]

85s have the extra vacuum switch which was pretty worthless so they got rid of it for 86+ models.

[Laitch]

If you agree that one of those wires is brown and the other one is violet with a grey stripe, that's for the vacuum switch.

85s have the extra vacuum switch which was pretty worthless so they got rid of it for 86+ models.

From Clymer—K100RS & RT Early engine and frame showing vacuum switch wire as violet/green :

[daveson]

The earlier diagrams from '85 has it as grey, Clymer, page 686 in my edition. Although that's not the earliest, I think it is for the US. Haynes also has it as grey, as well as the BMW rider's manual. Grey and green both start with gr in German as well, and the German wiring diagrams has gr as the colour code. And they wonder why a bloke bangs his head against a wall.

I think the draughtsman at Clymer might have had a bit of help from our good friend Jack Daniel's that night. For example look at page 696 where he spells switch as swiych. That's how you spell switch after a few Jacks, and that's how you pronounce it too. Nowadays instead of head banging I prefer a bit of tub thumping pissin the night away.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.youtube.com/watch%3Fv%3D2H5uWRjFsGc&ved=2ahUKEwjZ58D75LiMAxUPT2wGHYFVDsAQ78AJegQIFhAB&usg=AOvVaw0Q-6qEbg_kObrDSA_EqHyH

It's only had 94 million views, what is wrong with people?

[Laitch]

And they wonder why a bloke bangs his head against a wall.

Only gard can save us from this doom loop by skillfully using a camera and/or a multimeter. 

[frankenduck]

FYI: I have the BMW wiring diagram software (SLP) and for whatever reason all of the K100 diagrams are drafted 5/85 or later so none of them include that vacuum switch.

[gard]

Well I think it is to a missing vacuum switch, I have a hard time determining colors especially on small wires this old. For sure one is brown the other could be violet/grey. The cut off wire was tucked up next to to radiator. Also found the clymer photo showing the vacuum switch and one of the two screws is missing see attached photos.

When I attach files to the post I see something like attachment id=1 but I do not see any thumbnail or photo when I hit preview button. What am I doing wrong? a little slow going in the garage today, its about 15F out there

[gard]

trying again, this is as close as I could get my phone and still be in focus

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[gard]

Plus the photos are rotated from how they appear on my computer?
Middle picture is upside down.

[gard]

Back to other problems on this bike. As expected the radiator fan is toast, the brush holder is melted and brushes pointing off in unnatural directions. I will probably go for the SPAL retrofit. The fuel return hose is deteriorated do most people just pick up fuel line at the auto parts store or should it be BMW? Same with the vacuum line that goes to the pressure regulator.

The wiring harness shows some deterioration in some places, worst is probably the connector to the gas tank, the copper wires look OK. Is there some kind of rubber coating I could glob on there to seal the insulation? I was thinking I could use RTV but something that is paint-on might be better?

KIMG2702.JPG (40.62 kB . 768x576 - viewed 259 times)

The inside of the air plenum looks pretty nasty, I guess when you go uphill the oily crap will drain back into the engine. I have some old diesel tractors where the piston blow by overwhelms the crankcase ventilation system. The temporary solution is run the crankcase vent onto the ground or into a catch container. I don't think the bike is that bad yet because it smokes some but uses very little oil.

More disturbing is there seem to be serious cracks in the 4 intake manifolds that are bolted to the block. If I lift up slightly they separate. Prices on the web seem to range between US $50 and $120 and I need 4 so that hurts a little. Any repair or aftermarket options? Can the air plenum be removed without disturbing the fuel injection?

KIMG2704.JPG (48.37 kB . 768x576 - viewed 259 times)

[frankenduck]

I use  5/16 (7.94mm vs OEM 8mm) generic fuel line but be sure to get fuel line rated for fuel injected systems.

I've used generic vacuum hose line but some auto parts stores now use the same line for vac lines and windshield washer fluid which has a much larger outer diameter that doesn't fit in the vac line outer "spring" which I think is there to keep the vac line from melting on the engine block.

Don't know if it's still around but somebody used to make a paint-on electrical tape goo. Try Goggle to see if you can find it.

Click here:  Replace throttle body boots


 

[natalena]

Kpartsholland and Motobins has the airbox-TB and TB-inlet rubber in stock, with expected lower end prices. I'm a Motobins customer and they're good to deal with. EME is worth checking too.
The Oetiker clamps work great, or worm drive .. I never plan on fiddling the job again so went with Oetikers.
Good luck. Cheers

[daveson]

Yep, the vacuum switch has been removed. At throttle body one there are two vacuum barbs, make sure both are plugged.

The outer coil for the regulator vacuum hose, I've just thought it was to prevent sharp bends which with a bit of vacuum help, might result in the hose collapsing. One day I started my bike, I was gearing up, and I noticed smoke on the left side. I stopped it. It turned out that a wire with a tiny tiny crack in the insulation was touching the coil, creating a dead short to the throttle body. Because it was so tiny, it didn't blow a fuse.

The smoke problem you have, there are many possible innocent explanations there. If your brick hasn't been started in a long time, it might be smokey for a while. You might have the oil level higher than usual, or a problem causing the oil level to rise. If you park it with the side stand, or it's normal park spot is leaning left a bit, or leaning forward a bit, these things can result in smoke for a while, but eventually clear up.

[Laitch]

Exterior fuel injection hose is SAEJ30R9. Gates is the most common brand. Fuel injection hose clamps must be used with it. You could get the exterior hose at NAPA, Autozone, Bailey's or most other well-stocked auto parts stores. Submersible fuel injection hose within the tank is SAEJ30R10 or BMW NBR/NBR. Max BMW in NH is the cheapest place I've found for that type of hose.

Blow-by oil from the crankcase enters the airbox via a z-shaped hose behind the #4 throttle body to be mixed with the intake air into the throttle bodies. That hose probably needs to be replaced. The whole air intake system from the snorkel to the airbox needs thorough cleaning and the filter should be replaced. It's probably constricting air flow—it and the mice nests and spider nests around it.
 

[daveson]

I've been waiting for someone else to say this, but if those wires were cut by a mouse, that would be a very smart mouse, like the ones that have dinner with a fork and knife. Over here in Oz our mice aren't that smart, but we do have the smartest kangaroos in the world. But they're a little bit slow when it comes to boxing.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.facebook.com/LADbibleAustralia/videos/man-punches-kangaroo-to-rescue-dog/637334188467962/&ved=2ahUKEwjn2PGx6LqMAxVXqVYBHa-xE3UQu6AFegQIFxAC&usg=AOvVaw33R792zDbhwLDX1hFo_lEa

[frankenduck]

We have eager gnawing squirrels here in Washington. The ceiling light stopped working in my upstairs bedroom when I was a kid. My dad grabbed a flashlight and we went attic exploring to check the wiring. Where the wiring went down into the ceiling we found a dead squirrel who had offed himself by gnawing through the wiring insulation and getting a full dose of 110V AC.

[gard]

Each spring I pull a mouse nest out from the top of the engine. A couple of years ago I was on the interstate when a mouse popped up from under the tank and ran up my arm. Have also found the muffler filled with grain in the spring. Makes a nice popcorn smell driving down the road. Air filter box full etc. We have chickens so we have mice, chipmunks and squirrels. Its a never ending fight. The chickens love getting up on the workbench and knocking tools and small containers of parts off onto the floor.

I just assumed that if was an unused wire, BMW or the dealership tec would of or should of taped up the ends.

I have had the bike since new and it has 142,000 miles, it smokes a little more and drips oil a little more now than 40 years ago.

[Laitch]

It seems like the increased starting speed control (choke) wires have been cut. If that is the case, it wouldn't have much effect on anything else. My opinion is that anybody who needs an instrument cluster light to tell when the "choke" is turned on doesn't have sufficient attention span or focus to operate a motorcycle safely for the long term. The "choke" lever light actuation in the instrument cluster was eliminated during Brick production sometime in the late eighties.

Good luck with your restoration.

[frankenduck]

The strangest mouse thing I've found in a K bike is a mouse nest filled with poison!  This is from a K75 that spent years on display in a bike museum. When I removed the airbox I found this mouse nest filled with light blue pellets of D-Con which is a US brand of rodent poison. Mice are supposed to eat this and die, not take it home and make a bed out of it.

[natalena]

Mice! Damn Mice. Release the Buff Orpington's lest we lose every brick!

[Laitch]

Mice are supposed to eat this and die, not take it home and make a bed out of it.

It's the color; it goes with almost any decor. They just can't bring themselves to eat any of it.