Only K75 & K100-8V use an in-airbox AFM. K100-16V use Motronic 2.1, K1100 use 2.1 & 2.2, and K1200 use 2.2. Mine is later the K11 loom with O2 sensor, Motronic 2.2 and 38mm K12 TBs. Suffice to say it's all K1100 electronics in K100 clothing but with the mechanicals of a K1200RS. Not new ground, but the garden needs weeding.

I've finally had a chance to have a more detailed squiz at the electrics, continuing with the crank but no spark or fuel pressure theme. Here's what I know: I actually have a very late K1100LT wiring loom, but still pre 7/93 when all manner of things changed. I do have an O2 sensor and an ignition amplifier. However, I was told the loom I bought was from a 1994 model, therefore I eBayed an ECU from that model year, and it's different. How did I suss this out? I noticed the sidestand switch was missing and that little two-pin connector was sitting there all lonsesome and needing to be plugged into something - or be jumped pin to pin. Some will know that if the sidestand switch is fecked, or the stand left down, even with the clutch lever pulled in, she'll crank all day long until the cows come home, but never fire. Trouble is on a '94 the stand switch wires to the Motronic relay and the fuel pump relay should be brown and brown/blue. Not mine, they're green/yellow and green/red, a sure sign that they're for an earlier model than 7/93. My eyes are crossed at staring through various wiring schematics looking for distinct patterns.

I have a later 13 61 1 464 717 Motronic ECU. I need an earlier
13 61 1 464 649 Motronic ECU.

Another question: does anyone know, when checking for 'opens' on the ignition amplifier, when probing pin 4 with an Ohm metre (isolated from the harness and the coils), and finding only a reading only on pin 2 and pin 7, does that mean she's karked it? The rest of the pins show no movement on the analogue voltmetre. I'm still having fun!

just a heads up twb .....some of the analogue meters put out 9 volts ( or more ) when on the resistance scale ....with some of the newer ecus around this may exceed the protection circuits - on inputs and outputs of these later ecus (mostly  at 5 volts working voltages )....also the loading to the circuits on some of these analogue meters  when on the voltage range is quite low in value and may effect readings on certain circuits

I know you knew that   but just be careful that you don't have a feed going into the ecu via an unexpected path when using the analogue meter

it is hard to tell if you have a low value on an input to an ecu ...without knowing the designation ...and likewise for an out put ...without the ecu being active ...

best I can think is to fire it up (turn it on ) , then measure the voltage applied to the input or output via probing the connector

far better to use the digital for some of these things ...

keep at it mate ...im sure you'll find a solution

Thanks, Chaz. I'm actually probing the terminals on the separate ignition amplifier and it's isolated from everything. I'm just checking for opens.

The battery's flat on my digital so I'm jusing a nice, heavy old Radio Shack analogue metre made some time last century.

Whilst sitting with my morning cuppa in pyjamas and slippers I twigged to the fact that I have a '93 K1100RS sitting in the garage that just might have the ECU I need. Yep, sure enough.

This arvo I've swapped the ECUs and attempted to fire the bike. I now have a fuel pump that screams, and decent fuel pressure, but still no spark.

Second go, I swap in the other bike's ignition amplifier. She fires as well as screams, will crank over rapidly but won't start. I release one of the quick release fuel connectors and there's heaps of pressure as they come apart with a hiss of fuel. But that pump is making some sort of racket not befitting a new girl.

Third go, I peer inside the tank at the screaming fuel pump as I turn on the key (brand new from EME) and isn't the fuel bubbling out of the crack between the two terminals and the fuel hose. A brand spanking new pump and she's got a crack in her. No wonder she screams. The other bike has a perfectly good fuel pump and I want to hear the project bike run. Today!

Out comes that screaming like a banshee, split pump and in goes the secondhand pump. Let's see how we go.

I'm reluctant to stick my hands into the full tank of petrol, or have to drain it, in order to remove the other bike's fuel pump. I've contacted John at EME and we'll see what he says about a replacement. It's a two to three day shipment from Colorado to Washington state. I can wait.

Two Wheels Better wrote:Whilst sitting with my morning cuppa in pyjamas and slippers I twigged to the fact that I have a '93 K1100RS sitting in the garage that just might have the ECU I need. Yep, sure enough.

This arvo I've swapped the ECUs and attempted to fire the bike. I now have a fuel pump that screams, and decent fuel pressure, but still no spark.

Second go, I swap in the other bike's ignition amplifier. She fires as well as screams, will crank over rapidly but won't start. I release one of the quick release fuel connectors and there's heaps of pressure as they come apart with a hiss of fuel. But that pump is making some sort of racket not befitting a new girl.

Third go, I peer inside the tank at the screaming fuel pump as I turn on the key (brand new from EME) and isn't the fuel bubbling out of the crack between the two terminals and the fuel hose. A brand spanking new pump and she's got a crack in her. No wonder she screams. The other bike has a perfectly good fuel pump and I want to hear the project bike run. Today!

Out comes that screaming like a banshee, split pump and in goes the secondhand pump. Let's see how we go.

I'm reluctant to stick my hands into the full tank of petrol, or have to drain it, in order to remove the other bike's fuel pump. I've contacted John at EME and we'll see what he says about a replacement. It's a two to three day shipment from Colorado to Washington state. I can wait.

Swap the whole tank and hear it roar?

There's no hole in the tank. Besides, you do know how many acres of solid, German Tupperware have to come off to get to it? A whole lot.

You should be able to lift the rear and bring the tank straight back then remove the fuel lines. It's only those ugly old heaps the K100 that you need to strip the faring. I can get the LT tank off like that so the RS should come. Unless of course it's got some duck feathers jamming it

Two Wheels Better wrote:There's no hole in the tank. Besides, you do know how many acres of solid, German Tupperware have to come off to get to it? A whole lot.

My bad grammar is now corrected.  

RicK G wrote:You should be able to lift the rear and bring the tank straight back then remove the fuel lines. It's only those ugly old heaps the K100 that you need to strip the faring. I can get the LT tank off like that so the RS should come. Unless of course it's got some duck feathers jamming it

It was the cleverest late night after drinking way I could include both spellings of the word!

In retrospect, a mere 'thank you for the idea' would have suffised.

Two Wheels Better wrote:

RicK G wrote:You should be able to lift the rear and bring the tank straight back then remove the fuel lines. It's only those ugly old heaps the K100 that you need to strip the faring. I can get the LT tank off like that so the RS should come. Unless of course it's got some duck feathers jamming it

It was the cleverest late night after drinking way I could include both spellings of the word!

In retrospect, a mere 'thank you for the idea' would have suffised.

No problem, it made me laugh once I figured it out.

Fuel pressure is a curious thing.

I sat and pondered my 'invisible crack' in the fuel pump end theory.

Why would a new pump scream so? It must have been coming up against resistance of its own. I'm using a plastic K12 fuel rail instead of the square shaped K75/K100/K1100 metal version. It has its goes-inta fuel hose and it comes-outta fuel hose connections the other way round. I reinstalled the new pump and swapped the fuel hose quick disconnects.

The key is on, the new pump primes quietly, as they do, the starter button pressed, the pump remains running, and in five seconds or less of cranking the engine over it stumbled, hiccuped, cleared its throat and roared into a steady idle.

It lives!

Patience, Grasshopper.

Woo Hoo!! Way to go, TWB.

YAY !!!

This rough as guts 30 second clip is a part of the first start up in the garage this arvo. I'll clean it up and post something better as the assembly progresses.

Now it's time to mow the lawn and then go have a beer. 


It's a balmy 22c here today!

You don't see the smoke from the tailpipe in that clip. It fog banked the garage so badly I had to place a box fan in front to clear the place. A big blue cloud covered the driveway and front lawn just as the local high school track club ran past. Half their heads turned! I slipped back into the shadows. After a while, as expected, it went clear. Just a Springtime mozzie clearing.

After fiddling with the hall sensor she idles steadily. It's roarty and loud at rev, which I'll correct with another baffle. The 50A charging system works. The ignition switch is fiddly, even after a recent going through. It cuts out randomly. I'll be ordering one of those from Germany - none in stock here. Next stop, my mate Dean's place for grinding, cutting & fabricating of the subframe.

Then was an extra spring in my step, so I mowed the entire lawn in an hour then enjoyed two thick and foamy Guinness' at the waterfront under the sun in Old Town Tacoma. It truly is 'Good for You'.

The engine was cutting out randomly as I was testing/idling/revving it the other day. A few wiggles of the electrical portion of the switch revealed it to be inconsistently connecting. I'd had it apart for a cleaning and dielectric greasing a few months back and it seemed to be OK to use, but at one stage with the key in the 'off' position the fuel pump would run. In spite of a search for a new ignition switch turning up none in the US, I've managed to procur one quickly.

There's nothing like a new K bike teile to definitively tick another box of the to-do list.

My replacement Motronic ECU and ignition module should be here today whether rain, sleet, snow or hail. It's sunny, in fact, going up to the low 20s this arvo. The postie ought not have too much trouble.

The eBay replacement Motronic box ($99) and ignition module ($40) arrived by post today from Wisconsin and Florida, respectively, in three days from either place! I plugged 'em in and voila!, she burbled to life. It's alright when you pay for an unknown quantity and they work. I can honestly say that only once have I had an item not be as advertised that's been sold to me by a fellow Beemer rider or wrecker/breaker selling BMW parts. Now I can whack the loaners back into the blue K1100RS for a ride this weekend. S'posed to be sunny and warmish.

The new ignition switch, out and in in five minutes, fixed the intermittent ignition drama, too.

I am anxious to get the Big Block out on the road, and I'm sure you mob are tired of hearing about it!
:suspect:

Never TWB!
Very envious and following along closely.
Cheers, Dee

+1 with Dee Why and am hanging off of every word.

K75cster wrote:+1 with Dee Why and am hanging off of every word.

+2, its great watching a project unfold.

I'll throw my hat in the ring as well. Love reading about these builds.

Two Wheels Better wrote:.......
I am anxious to get the Big Block out on the road, and I'm sure you mob are tired of hearing about it!
:suspect:

ZZZZZZZZZZZzzzzzzzzzzzzz..... whaaat??

Just kiddin'. Eggselent read

Just elbowing to see if you're awake.

RicK G wrote:You should be able to lift the rear and bring the tank straight back then remove the fuel lines. It's only those ugly old heaps the K100 that you need to strip the faring. I can get the LT tank off like that so the RS should come. Unless of course it's got some duck feathers jamming it

True...but I modified the ugly only heap of a K100LT to be able to get the tank off without removing any plastics. Its worth the effort too. All it took was longer fuel lines and relocation of the clips on the ends of the fuel lines. I have since traced some quick release connectors to locate near the fairing vents to eliminate any unscrewing.

RicK G wrote:You should be able to lift the rear and bring the tank straight back...unless of course it's got some duck feathers jamming it

I haven't seen him round lately. Word from some of my customers is that he seems not to answer email queries about K parts, too. Hope all's well up there.

He did just drop out of here for no reason I could see and I cant find any recent posts on the motobrick forum either.

In case some of you thought this BBK project had died a death, and it has come along slowly lately due to work load, family gatherings, and just plain warm weather laziness (mid 20s to 30s for over a week here and no rain in a coupla months!), it is still underway.

I have managed to sort out the later K11 wiring loom and got the Motronic 2.2 running, sans O2 sensor still....the black cloud out the pipe when I give the throttle a bloody great big stab is proof she's rich as. I'm gunna take Kiwi Malcolm's sweet little custom-made exhaust connector and get a mate to weld a bung for the O2 into it facing inwards discreetly just above where the stands would come to rest.

That sorted I'm onto a local marine upholsterer down on the docks who can make me a lightweight plastic seat base then cover it with dense foam of the sort what goes in high-end yachts and such, then a marine grade, non-slip grippy vinyl to cover it all. I'll attempt to replicate the profile of the F800S seat I was gunna use. The rear of the frame will now only require a sawing off just where the skinny bit attaches to the fat bit. The skinny bit will become a handle cum number plate, indicator holder, angled upwards for the pillion to grab ahold of.

Just for fun I came in from mowing the lawn, hot evening, sun setting, still near 90F degrees, sipping an extra cold Guinness, and as I walked past I switched on the key, flipped the 'killswitch' to vertical, pulled in the clutch lever and gave the green go button a quick stab. She leapt to life with a growl befitting a caged beast whose mechanical growl spoke plainly and with some urgency, saying, "Ride me the f#ck out of here and down the road like it was meant to be, will you!?"

keep at it Dazza

not too far to go now

charlie99 wrote:keep at it Dazza

not too far to go now

Thanks, Chazza. I appreciate the encouragement.

Of the four bikes in this garage only one is ready to head out at a moment's notice. That, unfortunately, depending upon your perspective, is the Oilhead.

The K1200GT has a blown rear shock which I'm swapping out today for the K1200RS' manually adjustable rear shock so I can ride the GT down through to Bend, Oregon and into Idaho's Snake River (Hell's Canyon) over the coming Fourth of July long weekend.

The RS I've got the ABS module out of (shipped today!) being refurbed and I'm waiting on Spiegler braided brake hoses.

As you see I've my hands full, but that's what we enjoy about it.

Hell's Canyon during the 4th of July weekend?  Yer kiddin' us, right?
Do you understand what the temperature is likely to be during that time?  
Tu eres mas macho que yo.

I would not be concerned about that, Daz carves a canyon with the precision of a surgeons knife.

The GT has had a suspensionectomy, up the back end, at least! Also drained and flushed the coolant, changed oil (Mobil One 15w50 full synthetique) & oil filter, checked pad & tyre wear, torque all exposed fasteners to spec, fixed a rocker cover oil weep, then gave her a wash. Good to roll Thursdee noight.

Yes, the Oregon/Idaho border should be hot as Hades, but there's this (Snake) river running through it. We are paddling, too. The weatherliars are calling for low 90s here, high 90s in Oregon so reckon on a hunnerd or more out there. That's one reason I'm taking the streamlined liquid-cooled K over the air/oil-cooled, barn door RT. The fans keep it under control.

I just found this mate...what a  super cool custom build!  I'll be watching your progress with the Frankenbrick closely.  

OG

I'm happy you like it, OG, and welcome back to the forum. I have not seen nor heard from you in a fair while. Glad you're back.

After a coupla months of being very busy, summertimey things in the way, that Yellow Peril K to finish up on, I'm back focused on the BBK. Tomorrow it's lights all round, indicators, tidying up the wiring, battery tray and ECU. I hope to have it rolling on the road by month's end. There's two gritty/café bike nights round these parts (Tacoma's Grit City & Seattle's Backfire) 2nd and 3rd Wednesdays and next month I'll attend both.

BTW, I rode it round the neighbourhood last week just before dark for the first time for a coupla hunnerd metres. It leaps at the first release of the clutch, but I run out of road before I can shift to third gear, it's that light and limbre. I am looking forward to a trip to redline through all the gears on an open road.

I am so jealous TWB. Good on you for a build well executed!

Today was a good day. I spent it in the garage....well, half spilt out into the driveway as it was only 25c and sunny - not as hot as it's been round here lately.

I knew it was gunna take some time, and was putting off the inevitable, but I went at the bar end indicators. The Pro Taper 'bars are 14mm ID and the K&S LED indicators are about 16.5mm OD. It's not a good fit. So out came the drill for a centre hole to feed the wires through then the heavy duty Dremel-like impliment was put into action to grind away the aluminium insides of the 'bars. I have wanted a tidy look without the clutter of indicators round the headlight or mounted to the forks. It took ages but worked.

Next up was the cooling fan. As I've used those four massive 44mm intake sleeves to mount the 38mm throttle bodies onto I had to sacrifice clearance for the OEM radiator cooling fan motor. I turned to the cheap and plentiful source - eBay - and obtained a 7" reversible, slim, shrouded fan and motor. Bloody hell if it too won't clear. I looked at mounting it to the front of the radiator and reversing the direction of rotation...what an incongruous lump of a thing sitting up there all exposed. Nuh, it's getting hidden away like God intended, at the back. I'll nip and tuck the shroud to make it clear the 'gooseneck' and hoses.

The other thing was the seat. I've not wanted to use anything like an original seat shape or seat pan. I like the shape and profile of the original BMW F800S/ST seat. I have attempted fibreglas, aftermarket seats from a Ducati, was even offered carbon fibre as an option, but they all come up short. I twigged to the idea of using a polyethylene cutting board - off-gas for the arse!?

I found a professional restaurant supplier down the street and bought a 24" x 30" piece in white, a 1/2" thick, and went to work with a black magic marker and a fine-toothed jigsaw. Once I'd got the rough outline, following the contours of the rear frame as it drops then rises to straighten out towards the back end, I clamped it into place with six carpenter's clamps and pointed the heat gun at it for a spell. Lo and behold it drooped and sagged (eventually, and with some force) and is now more or less following the intended bend.

The local marine upholsterer will contour and sculpt a bit of hard seat foam for me then whack a non-slip cover over it, rivet it down and we'll hope that it looks motorbikish enough.



At the mo' the bike is in parts and pieces again. I had wanted to have it ready for the annual (and top secret, ssshh) Isle of Vashon VME gathering this coming weekend. Ain't gunna happen, lest I wanna perch on a slab of plastic and keep moving lest it overheat....but at least I've got indicators, and a cutting board on which to cut the olives for my martini as I await the towie.

Polyethylene cutting board seat pan in profile. I left it overnight clamped to the frame and she isn't about to 'spring' back into her previous shape.




Sturdy, metal-framed, low-profile, double LED bar end indicators which just might survive a gentle tipover and can be seen allround, front and rear. No need for a dash mounted warning lamp!

I like those indicators!  They prompt a question, though.  The K1200 bikes relied on rubber mounting the engine to the frame, didn't they?  With the (light) indicators on the ends of the bars, you wouldn't have the dampening effect of bar end weights.  Do you foresee a need for something to tame the vibes of the "big block?"
I'm enjoying this report tremendously.  I can't wait to hear of the final result.  Thanks for putting it up for us. 

There's a rubber expando sleeve inside the units which when I tightened them should isolate the fragile LEDs to a degree, and I ground away the 'bar so that it's not an interference fit between the LED mount and the inner 'bar. Let's hope that is enough for a vibe-free long lasting existence.

LEDs are pretty tough.  Actually, I was thinking about the effect of vibes on the rider's hands.  More than one K-bike rider has commented on their hands going to sleep due to vibes felt through the grips.  A bigger bore engine could become something of a paint shaker.

Well, we'll see soon enough. I have never intended it to be a super tourer, just a runabout that points and shoots. From the few hundred metre runs up and down my street it doesn't feel much different, vibe-wise, to a standard K.

"Awesome Project"

Enjoyed following the build and write up looking forward to the conclusion TWB if she goes as well as she looks you have a winner mate.

BIG D

After a much-needed pause to catch my breath the Big Block project has been bumped started. The roller is down at a mate's workshop geting some subframe slimming done, as well as having a fibreglas seat pan fabbed up, foamed and upholstered. Pictures soon.

The simple thing to do was to simply slice a cut halfway through each of the rear frame sections 10cm behind the shock mount, vertically, bend inwards the frame rails, then re-weld for strength. No weight will be supported back there but the number plate, turn indicator/tailight combo and the rear half of a slim mudguard. The bucket-type seat will angle into a fastback style allowing just enough room for a pillion for short hops. The flat-footed reach to the floor is a cinch for short arses. At the front end the seat will slope up against the petrol tank ala stock, but not as high up. It's held in place by a wingnut secured to a stud embedded into the fibre and attaching at the cross rail mid-subframe, and another wingnut at the rear loop, which has been welded back on after approximately 60mm was removed from the length of each side of the frame rail. The seat/subframe ends just slightly at the outer radius of the back tyre, for a balanced look - my eye is not too terribly pleased aesthetically by tyres protuding out into empty space. No accommodation has been made for the line of the angled petrol tank to match the seat or frame rails. This is a budget job.

The Motronic unit is housed in a stamped sheet steel box under the rider's portion of the seat between the rails, for ease of access. A 12A lithium battery will rest on its side under the intake sleeves/throttle bodies in a rubber insulated housing. There will be air seen through the back end of the bike. No serious attention is being paid to looks. It's just an incongruous lump of a driveline, a place for a backside, a set of 'bars, a tank and two wheels.

This year's monthly Grity City moto night in grimy old Tacoma is coming up and I hope to have a plate lashed to the bike for a shakedown run to the event. Anything that's fallen off will be my telltale Hansel & Gretel story so I know the right way home.

The next Grit City is on the 13th of April.

I just read the entire build thread and am now on the edge of my seat awaiting finished pics!

Thanks for documenting and sharing TWB!!

Glad to read that you enjoyed it. It's taken a fair while but that's because life, work, travel and other bike projects get in the way. Won't be long now. It's gunna be a blast to throw a leg over in earnest and get along down the road!

Two Wheels Better wrote:Glad to read that you enjoyed it. It's taken a fair while but that's because life, work, travel and other bike projects get in the way. Won't be long now. It's gunna be a blast to throw a leg over in earnest and get along down the road!

Yes. I've very much enjoyed the documented journey (so far), details of your discoveries, challenges and solutions and the humor (humour?) with which you share it all.

I may have to saddle up and ride north to "squiz" your creation when all said and done.

Thanks again...

In the rough...

The seat will be skinned by Friday, the Motronic 2.2 ECU is attached by rubber mounts under the fibreglas seat pan, out of sight, the bung for the O2 sensor has been welded into Malcolm's excellent exhaust collector, the aluminium number plate panel is screwed onto the rear loop of the subframe and the turn indicators/tailight assembly and headlight are being electrifed this arvo. I just need a the front half of a K11 rear mudguard (fender) to keep the splashy stuff of the sparkie bits.


Just before re-skinning, the fastback-type seat is perfect for the low-slung cruising riding position I was going for; feet flat on the ground and a short reach to the Pro Taper ATV 'bars. We fabbed the fibreglas seat pan to dip down into the curve in the rear frame above where the ECU and battery would usually be located. The foam is dense enough and shaped to form a saddle-like bum holder just forward of the frame's cross brace. The side view of the seat is not too imposing and it looks like we pulled it off. The telling will be in the finished product, a pebble-finish, non slip, stretchy material commonly used on boat upholstery.

This I am Jonesing to ride!

Arse end...


Next stop, battery hidden, lights, indicators & number plate bracket.

Lookin' good TWB, but you've gotta get rid of those chicken strips!