Bringing K75 back from the dead.

[The Mighty Gryphon]

1980 R100RS? 

I think you will find that there may not be very many of the members here who can answer your questions and provide any useful information.  I know that I have absolutely no experience with your bike. 

[daveson]

I'll guess they told you the truth, if it's got three cylinders ( or three coils) cause a three cylinder boxer is as rare as you can get.

[Sopp]

Now I'm really confused.  Looked up a bunch of images of an R100 RS.  Mine looks nothing like an R100 RS.  VIN last 7 numbers are    6223203.  What I have looks just like a K75.  I'll take some pics tomorrow and post them.  I will also recheck the VIN ( I'm sometimes a little dyslexic ).

Nothing is ever easy for me...........

Sopp

[Laitch]

Drilled the cap per specification in the link, but still can't get it open.  Try again tomorrow.

If you drilled it exactly as the post described, put a screwdriver or rod through the hole with its handle angled like in the attached photo then push forward. The end of the screwdriver—or rod—is inside the loop of the latch. If this isn't working for you, the screwdriver might not be deep enough or your angle needs to be changed some.

[Laitch]

Now I'm really confused.  Looked up a bunch of images of an R100 RS.  Mine looks nothing like an R100 RS. 

Is this the same Brick you had in 2019, Sopp. Click here to confirm. If so, its identity has been known since then and we still can't convince you the key didn't have a chip.  If not, post a few photos of it.

[frankenduck]

If you drilled it exactly as the post described, put a screwdriver or rod through the hole with its handle angled like in the attached photo then push forward. The end of the screwdriver—or rod—is inside the loop of the latch. If this isn't working for you, the screwdriver might not be deep enough or your angle needs to be changed some.

There's another method for drilling the gas that I've read about. (But never personally tried.)

You could also drill a small hole up near the front and use a screwdriver or other tool to push back the tang at the front that holds the gas cap closed. Note that pushing down on the gas cap makes it easier to slide that back.

[The Mighty Gryphon]

Do you have the BMW folding key?  If so, I suspect the missing "chip" is probably the small BMW roundel.  It has nothing to do with unlocking anything, it's just a "Stinking badge".*

Like others here, I am eagerly looking forward to when you can post a couple recent photos of this bike your are working on. 

*semi obscure movie reference

[Sopp]

1. Rechecked VIN 6223203
2. Yes this is the same Brick as the pictures from 2019.
3. Measured twice, drilled once in gas cap.  Probably not pushing hard enough, since it hasn't been opened since 2019.
4. Key is still MIA

From the 2019 pics.............What have I got?????  If it's a K75, why dose the VIN say it's an R100RS from 1980, and what do they mean by "for European Market"?????  Dose not meet U.S. specs?

I'm going out to work on it.....................
Sopp

[Laitch]

From the 2019 pics.............What have I got?????  If it's a K75, why dose the VIN say it's an R100RS from 1980, and what do they mean by "for European Market"?????  Dose not meet U.S. specs?

You've got a K75 just like you had in 2019. Where is the VIN located that gives you that number—on the frame or on a piece of paper somewhere? Have you looked on the frame to the rear of the coolant tank? European market means that it was made for purchasers in Europe. It would have different light switches that didn't need to conform to USA always-on standard and maybe some other minor differences depending upon which state, province or country was its destination. It was likely shipped into the Western Hemisphere by somebody who owned it.

[frankenduck]

Euro bikes have some minor differences. For example, Euro (and other non-US bikes) have a headlight switch while US bikes don't and have that circuit shorted so that the headlight is always on. US bikes have a high altitude plug that adjusts the mixture for the less dense air. Non-US bikes don't have that.

Euro switch:



Where did you get that VIN? Look for the VIN stamped into the frame on the right side.

[Laitch]

Post a photo of the number on the frame. Based on the usually accurate information from Snowbum's BMW motorcycle site, the serial number range for the K75RT model would be able to include your Brick's number if the number was actually 6229209 or any variation to the last three digits numerically earlier than 305. With that in mind look at your ride's frame. Maybe the nines were worn down into threes, or some other mutation.

[Sopp]

Total VIN on right side stamped in is   WB1057307N6223203
The number the left side paper tag is  WB1057307N6223203  Not sure if that tag is really paper but it is applied to the frame.

Pulled the springs out of the forks today and dropped tree down lower on the spring tubes.  Will reassemble the bag mounts tomorrow and the front should be done. If it looks presentable I'll take pics to post.

Sopp

[Laitch]

Total VIN on right side stamped in is   WB1057307N6223203
The number the left side paper tag is  WB1057307N6223203 

Thanks for that.

Those numbers don't conform to any of the K75 records I've found. The fourth digit in all K75 622 series serial numbers is 9, not 3, except for one number-6220000. You've got yourself a mystery there, Sopp, but according to the photos you posted here in 2019, it was a K75 until you got a hold of it.  I'd still like to view photos of the frame stamp and tag but am looking forward to any updated photos of the Brick that you can provide.

[frankenduck]

That's a weird VIN issue.

The decal on the left frame is required to show that the bike meets NHTSA eligibility requirements for import.

[Sopp]

The mystery is over.  The VIN is actually.........................6229203....................that 9 is rather scratched up.  1992 K75RT US market.
And it still won't start.

Sopp
 

[Scott_]

Like any motor, you need air, fuel, compression and spark.
You say you have fuel, and obviously you also have air.
The battery power goes thru the ignition switch, then thru the kill switch to the +side of the coils. The - side is switched on/off by the ignition controller, that gets input from the HES on the front of the engine.
That's about as simple as it gets for what you have left.

[Sopp]

Printed out a copy of the wiring diagram, blew it up big enough to read, and spent the last 3 days going over every wire with a magnifying glass.  Everything works as it should except: The turn signals don't work, and I have no spark at the sparkplugs.  Never failed to start back in 2019. Nothing changed since then. No wires chewed on by mice, all connections tight.

Any ideas on what and how to test the system would be greatly appreciated.  Been a backyard mechanic all my life, EXCEPT on these damn computerised systems.  My old cars are fixed by me. I don't even change oil on my newer stuff, afraid I'll screw something up.

Thanks to Laitch for combining the earlier thread with this one. Don't know if I mentioned this before but the reason for the 3 wheel conversion is that I have no sense of balance.  People won't even take for a ride since I'm also a terrible passenger.

Sopp

[The Mighty Gryphon]

Since the signal for the injectors is coordinated with the engine rotation by the signal from the Hall Sensors, you can check if they are working properly by cranking the engine and listening with a long screwdriver for the injectors pulsing.  That will give you alittle idea of which half of the spark system is giving you trouble.

[Martin]

Once you have a blown up diagram get it laminated. Stick it on your wall and use China graphic pencils to mark out your circuit. They can be had in various colours. When you're finished the pencil traces can be easily removed  with wax and grease remover.
Regards Martin.

Wiring Diagrams Laminated.jpg (45.66 kB . 768x432 - viewed 186 times)

[Laitch]

Since the signal for the injectors . . . you can check if they are working properly.

Not any more. Sopp's Brick has a carburetor.

[Sopp]

Went through damn near every wire on that trike and everything works properly.  I have power everywhere it should be with key turned on.
Except it still won't fire.  Only 2 places that could be the problem: the H.E.S.  or  the I.C.U..  Does anyone know how to check these items?  I have power to each coil via the GnCe wire, and power to the ICU.
Does the H.E.S. ever go bad?
Does the I.C.U. ever go bad?
Can't help but think it's in the wiring some place, ran beautifully last time I tried to start it ( 4 years ago ).
Is there someplace else on this board I should be asking these questions?
Took some pics of the air suspension, now that it's up and working, but can't find the pics when I try to attach them to a post. Will try again later.
Sopp

[Laitch]

Does the H.E.S. ever go bad?
Does the I.C.U. ever go bad?

Yes.

Four years is a long time to leave a motorcycle idle. Oxidation befouls connections. It isn't surprising that it doesn't start despite starting years ago. It's a story that has been repeated here often but your story is unique because you've changed the fuel system from injector to carburetor. You need a fully-charged battery and you need to spray fogging oil into each cylinder before starting because the rings could be seized in their grooves and not sealing the cylinders well enough to provide sufficient compression for ignition. That is old-school stuff and you probably have taken appropriate measures, but I'm mentioning it anyway because I can. 
There are tests for both in the K100 2V Troubleshooting Guide link at the bottom of this post in the Repair Guidance section.
You should perform the so-called Ignition Module Tests in the troubleshooting guide to compare your ICU setup with the test's voltage and resistance figures in the table. There is also an HES test. Many functions are similar in the K100 and the K75. For the HES test, a 12V LED with pigtail is required.

[Sopp]

The front air bag is done, for now, upper attachment will be covered later.

Still won't fire.  Been checking grounds and every connection I can find.  Might have to start replacing $$$$ stuff next.

Sopp

[Sopp]

IMG_20230719_142945658.jpg (99.41 kB . 768x576 - viewed 121 times)

Could this be my problem???  That looks like a burn to me.  When I cleaned it off there didn't seem to be any connection between pin and any other "line" in the mother board.

Anyone have an extra I.C.U. they would like to sell?  One on Ebay for $75 and free shipping, but I thought I would check here first.

I need to replace it before I stick any more money or work into this brick.

Thank for all the help I have received from everyone.

Sopp

[daveson]

Don't remember the details, I'll have a squiz at your thread on the weekend.

I think it's cranking but not running. I'd go to the basics. I think you had spark, spray some starter fluid down the carby while cranking to see if that fire's it up.