It's begun. The requisite bits in the garage now are: an '89 K100RS frame, complete K1200RS engine (anyone need a six speed gearbox and bell housing?), complete K12 wiring harness, K1100 bell housing, K1100 gearbox, Paralever swingarm & K1100RS final drive, K100-16V Marzocchi forks, 3 row radiator, K100 petrol tank, front 3.5 x 17" & rear 5 x 17" five-spoke wheels, 305mm GS front brake discs, four-piston R1100GS calipers, '86 on K100 footpeg assemblies, exhaust, seat & miscellaneous other bits 'n' pieces, with the rest on the way, still being hunted down, or being spied on at current auctions, etc.

The idea is to put together, using as many stock BMW K bike parts (and from other BMWs) as is possible, a minimalist K100 standard with a generally relaxed seating/foot peg position, using a K1200 engine - hence the term big block, though we all know it ain't much bigger. It'll be a northern hemisphere Winter project. I'm not in a rush.

It's not meant to be a swift and sleek touring machine, a rakish sportsbike, a knobbly dualsport, a sit up and beg cruiser, or any sort of trendy café racer. Just a basic bike with a prominent engine, wheels with modern radial tyres, 'bars with a slight rise and pullback, and a comfy place to perch my derrière. Though I'm sure I'll flog it down to a café or two.



Let the midnight oil burn.

Gees mate you sure tempting me with that 6 speed

Looks very interesting, please keep us informed on progress as I am sure you will have a few very interesting challenges.

sweet !

this could be a very interesting thread dazza 
keep at it mate ......and post those pics

Thanks for the encouragement, ladies and gents. I know it's gunna be a challenge and that there'll be roadblocks and head scratching, back aches and dirty fingernails, questions needing answers and technical difficulties to overcome. I have the tools, a welder, and a painter and powdercoater nearby. I'm up for it. I have a vision and it involves a particular and favourite model BMW of mine (or ours in the collective?) done just a little bit differently. I look forward to eventually lofting the front wheel but I'm also hoping it doesn't come off mid-flight. 

Better show photos of cable ties to be used....Blakey must approve this modification.

ainsjac wrote:Better show photos of cable ties to be used....Blakey must approve this modification.

Someone tell Herr BlaKey, only the highest quality blue cable ties will be used so as to match the new hue of the frame. OK, maybe a few red ones 'cause I like Ferraris, and it's a BMW Motorsport colour. But so is white...............
Hmmmm.

Looking forward to watching your progress TWB.
Enjoy.

Definitely keeping an eye on this thread.

You are setting yourself up for a fall if you can't colour match the zip ties and the frame colour. :suspect:

Full steam ahead Dazza!

This looks to be a really interesting project.  Please make sure that you post all of the gory details, as to me this represents one of the main reasons why the K is such a great bike: as standard it came in many different flavours so that it suited plenty of tastes, and you are taking the concept another stage further.  I love it when people take the time and energy to subtly alter their machines to become precisely what they want. Best wishes with it.  

I am very intrigued and will certainly be following along.

Good luck with the build.

Cheers.

Colour matched cable ties are easy. First buy the cable ties that you prefer then get the frame powder coated the same colour.

Al

The engine being stripped of gearbox, clutch and flywheel, bell housing, TBs, fuel rail and hoses, alternator and starter. The starter nose cone was quite stuck and gentle tapping with a rubber mallet caused the nose to snap off clean before the o-ring. Good thing I'd found a clean, secondhand starter a month or so ago before going home to Australia for three weeks. Bad thing is that I brought the starter with me to OZ and it's there in my shed now. Doh!



Six cog 'boxes are quite a different animal to the five speeders. A handy person could fab up some fancy frame bracketry to turn their K100/K1100 into a six speed if so inclined...benefits are better overall gear ratio choices for cruising and hydraulic clutch actuation. It would be some kinda work to accomplish.



Due to the narrow top transmission rubber mounting points, and for later on, the lack of suitable footpeg bracketry using even an extensively modified version of the K100/K1100 frame (as Larry Romestant has done here) I reckon it's beyond what the average shadetree mechanic is gunna attempt. But, armed with cutting tools, a frame jig and suitable welding equipment, it could maybe kinda sorta might be able to be done. After a good squiz at my options scattered about on the garage floor, I'm going on the (relative) cheap and five speeds will do me. It's going to be a roadster, not necessarily a long distance mile burner, but it oughta be quick off the line...



And this would be required, too.



It's suprisingly clean inside there. Though I'm going to have to tape off the open intake ports before literally scraping off 12 years of accumulated oil and dirt sludge on top of the block before removing the timing chain cover and cam cover to check the chain/tension, chain guides and valve clearances before resealing it. The engine is reported to have under 65K miles on it. There is a minor rash on the forward lower edge of the magnesium cam cover where it had fallen over. I'll also have to replace the crank cover lest I wish the radiator hose to flop about out in front. I've found a black K1100 crank cover in good nick (which has the passage for the hose) for cheap and may purchase it to keep things tidy and less vulnerable.



It's a filthy bloody dirty thing. I love it!

No pain, no gain

Number 4 in the diagram has, internally, about twenty small 'feet' held in place by the tiniest little coil springs atop each one. One of the springs had escaped its confines and was floating inside the 'bell housing'. I was surprised I could actually see it, I'd not have noticed any of them missing. I carefully pulled apart the alternator drive coupling and attempted to replace the spring which holds in the equally tiny bloody little feet. Not a chance. I'll need a set of jeweler's screwdrivers and Hubble telescope level of magnifying glass. No complaints. This is heaps of fun. The many hidden wonders of a K bike motor are revealed as it is reduced from a brick to a stone to a pebble to a grain of sand.

I'm looking forward to seeing the progress, Nice project Dazza !

Great idea in great hands.

There is something about the idea of building your own perfect custom utilizing parts from 3 generations of the same basic platform. Very cool.

Those little springs are such fun

Two Wheels Better wrote:
as it is reduced from a brick to a stone to a pebble to a grain of sand.

Nice analogy. very eloquent

ssj_Gill wrote:

Two Wheels Better wrote:as it is reduced from a brick to a stone to a pebble to a grain of sand.

Nice analogy. very eloquent

Sometimes I go like that. Long-time forum members know it's habitual.


We now have the correct transmission to engine block flange (bell housing), five speed gearbox, Paralever swingarm, both driveshaft pieces, and an RS final drive and torque arm, all in black. Does anyone have a K100-16V/K1100 clutch pushrod available? eBay has a few but.

Two Wheels Better wrote:Does anyone have a K100-16V/K1100 clutch pushrod available? eBay has a few but.

PM sent.

38mm TBs before cleaning. I am replacing all of the rubbers, the O-rings at their base to the cylinder head and using new clamps. I recognise that using the original K12 airbox is out of the question due to space limitations so a rack of K&N-type tapered air filter pods may be my best choice, keeping in mind that there's nothing like a voluminous airbox to help make tractable power and to keep intake noise to a minimum - though the incoming air rush might sound so sweet!



The fuel injectors, rail and built-in fuel pressure regulator before cleaning.



Stock footpeg brackets from a post-'85 model. I'm going to drill and machine to lighten them and make them as airy as I can while retaining the necessary ribs for strength. If the bike is indeed used primarily solo then a nice set of BSK Speedworks rearsets might be in order.



The main wiring loom is a plate of spaghetti mess and also huge in weight and size so it will need to be paired down to something manageable while retaining its usefulness. The large, plastic box which houses the ECU and acts as a junction for the harness will be tucked up and away under the tank and main frame backbone in a custom aluminium box, partially hidden from view.



No leaks from any seals and very tidy splines (liberally slathered in lube) on all of the components such as output and input shafts, and driveshaft, indicate that they were maintained regularly. I want few surprises! Best part is that every component will have an eye and hand upon it before final assembly. Talk about getting intimate. My riding partner is wondering how I can spend so much time in the garage of a night, and even early mornings before work. It must be a mistress suddenly has all of my extra attention. Yep, and she digs dirty fingernails and the smell of petrol, cleaning chemicals and used sump oil.

robmack wrote:

Two Wheels Better wrote:Does anyone have a.....(name the part need)?

PM sent.

This forum is awesome. With just a few words in a time of need, the K brethren step up and assist. Thanks to you all. If there's anything I can do in the way of spares....just ask. Cheers.

More goodies have arrived. Yesterday a petrol tank from Canadia, along with some K1100LT calipers.



Here's what I am hoping I can get it to look like after a bit of elbow grease is liberally applied.






A radiator, which was bought solely for the fan as I have already a three row radiator, and a 16mm K12RS front master cylinder, came from Calithumpia. If anyone needs a clean two row (sans fan) then this one is available.

I've also located a seat which I think will do the job. It's got a good 'basin' for my bottom, is low enough for a flat feet stance, and shaped to a point at the back behind the pillion for a streamlined look. There's also a bit of a bumstop which we refer to as the pussy pad. There's a coupla points at the front which don't allow it to seat (pun intended) up against the back of the tank so they'll be modified. The back of the frame will be channeled to suit the seat's contour.



While I was at it I grabbed a secondhand 'Superbike' handlebar, bought cheaply ($10) for its bend to see if it suits. It's a 7/8" job so it's not a straight bolt on and go 22mm version but obtained for checking angle and width. A pair of LSL or Renthal will be the final choice.





The RS final drive I intend using is a 31/11 ratio (2.81) and if it doesn't settle the revs enough at speed I can whack in a set of secondhand ring & pinion gears from a used R1200C 33/13 (2.54) FD that's laying about at work.



I like the look of this H4 headlight and ears, see here on a Speed Trip, and available through Spiegler USA's catalogue. What do the collective think of it?

Yes, that is a nice light, it was one of the ones I was debating using for my build.

I think the headlight will look pretty good.

After sifting through the used bins at work for spares, or opening many crushed or damaged parcels from eBay and such, only to find grimy secondhand parts that the seller could have at least half wiped off with an oily rag, it's quite loverly to open a box and see something shiny and new for the Big Block project.

These are objets d'art, no?

Back to reality. The starter/alternator clutch assembly has some previously mentioned tiny little coil springs and accompanying one way 'feet'. I'd noticed an errant spring floating in the oil residue of the engine back cover, the 'bell housing', if you will. Upon closer inspection I saw that several of these springs had come loose and then spotted that the cage holding the bits together had actually fractured, causing several of the feet to slip out. The cage is in bits as evidenced by this piccie here. I managed to locate a clean used assembly for under $60 shipped. I am still missing one spring from the original - see them at the end of the small screwdriver in the pic. All of the the engine covers are coming off anyway so I hope to see it sitting in sludge at the bottom of the oil pan. I'm glad I looked. A spring like that could do some damage if it actually managed to reach a soft bearing shell. Unlikely but possible.

Remember that tiny coil spring that was missing, the one of twenty that sit inside the alternator/starter clutch housing at the top of the motor in the back under the 'bell housing'?



Here it is, or most of it. A smaller bit was captured in the residue at the bottom of the oil pan.



I discovered it here whilst removing all of the K12 engine's covers for a general tidy up, valve clearance check and oil sludge removal. It was stuck right into the screen of the oil pickup. Three cheers for fine mesh!

     

Always a relief to find nasty bits like that!

Aye Dai, it is good to get into the nitty gritty before it gets into you. With the block, head and water pump still intact I think now I'm going to strip it down and replace the gaskets and seals, freshen up the valves/seats, possibly hone the cylinders and replace the rings as needed. The bike had 65K unknown owner/rider miles on it - with excellent compression to be sure. But as there are small chunks of carbon in the oil pan it's worth a good going over. I want it to be fresh as since I'm putting some effort into this Winter project. I have the time and the tools.

The light and seat would go well together I.M.H.O. as they say. Those wee springs are very wee indeed. Rather you than me on that one. Are you planning a professional polish of the tank?

88KE wrote:The light and seat would go well together I.M.H.O. as they say. Those wee springs are very wee indeed. Rather you than me on that one. Are you planning a professional polish of the tank?

The seat will go over a modded subframe - I have an idea about an aluminium version bolted to tabs welded to the main part of the frame. No straight lines back there.

Yeah, those springs are indeed tiny. The new alt/starter clutch assembly is intact and going in this weekend.

The tank will be polished to the nuddie, dunna how professional it'll be though as it's me doing the rubbing.

Once I get the bellhousing, gearbox, swingarm and final drive screwed together then I'll 'dry build' it all to see how things fit. If satisfied it's off with the clothes and down to the beauty parlour for a proper prettying up. Then back together she goes before a night on the town.

All items removed are going on the scale and their weight recorded. It's about horsepower, of course, but mainly it's about lightweight and simplicity. If it has a purpose then it stays, otherwise it's off to the glue factory like a crippled horse in days gone by.

Luv it! Your attention to detail (and description) takes me back.. And makes me excited about this thread!

theApehouse wrote:Luv it! Your attention to detail (and description) takes me back.. And makes me excited about this thread!

Yeah, Greg, still a bit wordy rappinghood. That'll likely not change anytime soon. We two do have some history and Beemers have been a huge part of it. Good luck on yer own project. Let's see some piccies.

Just for clarification for the other members. TheApehouse and I knew one another back in the '90s in New Mexico when I lived there, and riding was what we all did. We just happened to reconnect here in the best li'l forum in the Kingdom! There's also a bloke on here I went to high school with back in the mid-'70s who rides a K. Small bloody world.

Whodathunkit!?

I started tidying in the garage today. It was 11c degrees in the shadowy sun so I threw open the double doors and aired the cold, Wintery place out. I now have almost everything I need, parts-wise, for the build to begin. A machinist mate is fabbing a 20mm axle to fit the 17" front wheel & Marzocchi forks based on the bearings & spacers, and from the axle diagramme available here on the forum. The engine has been stripped of its covers and the innards cleaned out. New gaskets and seals are in. A timing chain tensioner was procured along with the plastic guides. At 65,000+ miles they sorta needed it.

Once I have the new axle in hand the forks will go onto the frame will go onto the engine will go onto the bell housing will go onto the gearbox will go onto the swingarm will go onto the final drive. On will go the brakes then the wheels. She'll at least be a rolla. I can then lay the wiring loom and switches, throttle bodies, hydraulics, tank and pump, mock up the rear of the frame to place the seat into position before cutting and re-shaping the 'subframe' to accept the F800S parallel twin's dual seat.

Once it's aligned and things are in order I'll strip it down again for paint and powdercoating. It feels good to get moving in the new year.

As with all things in life it's good to have options. I have worked out which 25mm ID wheel bearings will work in a five spoke front wheel from a K12 series bike (see another post on the forum, dunno exactly where at the mo')....but desired to also have a workable axle solution for the stock dimension 20mm ID bearings. Here is the preliminary design in brief.


Here the roughcut axle protrudes from the fork leg. This end will be lopped off approximately 20mm from the outside edge of the fork leg and a 10mm hole drilled through for easy axle removal with a 'Tommy bar'. The metal is 4140 and has been tested for strength at a metals specialty firm which electrically tests for hardness and stretchability. Since it's not stainless steel the exposed end of the new axle will be etched and primed, and the areas of the axle inside or under collars will be slathered with anti-sieze compound to minimise corrosion.


This end eventually gets tapped for the 10x20mm screw that 'pulls' all of our early K bike's axles and seating collars snug, and in concert with the four fork leg bolts, pinch the axle. Note the 25mm OD sleeve which takes up the slack around the 20mm diametre of the new axle. How do we intend to secure this end of the axle if it doesn't tighten sufficiently? We don't want the end screw and the opposite ends pinch bolts to have to do all of the work. We'll slice this 25mm collar from end to end so that it becomes a shim and is able to be tightened against the axle by the two fork end pinch bolts - but only if it requires it. We'll know this when the axle is fully machined and the threads tapped. The stock, internal 20mm axle centre spacer between the original bearings is utilised. New bearings are going in when the axle is fully ready.


Here the OEM axle spacer has been shortened about 40% from stock so it just slips inside the wheel seal and seats against the inner bearing race.


Here the stock axle collar seats neatly up against the entire outside edge of the sealed wheel bearing. No adjustments need to be made to this side collar since it's the wide end of the axle where the fork lower 'floats' or self-centres.


Here the heads of the rounded Torx screws which hold down the 305mm brake discs to the wheel (from an F Series GS, same discs as an R12 Series GS) have been machined down about 1.5mm so they clear the inside edge of the Marzocchi fork legs as the wheel spins. Clearancing the fork legs a few mm's right where the screw heads pass by is an option as well. You decide which is tidier.

The ABS sensor bracket will be ground away cleanly, the forks refinished and the incongruous ABS warning sticker will be removed as this bike is gunna be sans ABS.


The entire fork assembly, brakes and wheel are clamped down to a work table to facilitate access - a few big words for making things a whole lot f*ck*ng easier. The wheel and discs centre into the middle of the callipers. Any minute adjustments to centre things up as needed can be made by adding or removing those wavy shims behind the brake disc mounting points.



The bloke who's fabricating this axle for me is a machinist for a Tacoma firm that makes hatches for nuclear subs and valves for nuclear power plants. This is kinderplay and he's enjoying it - will save the plans for making additional axles as needed by anyone else. He rides a coupla different Beemers, a new R1200GS Wasserboxer, R1200ST, as well as a Guzzi and several Harleys. The bloke who has volunteered his workshop space is currently a K75S rider but has had a few Airheads and a K100RS. They're happy to see this idea through. I will owe them both a bottle of something warm and peaty, preferrably single malt.

I've found the perfect brake disc hold down screw from BMW. It's a T30 Torx, part number 34 11 7 700 989, with shoulder, 8 x 27mm x 1.25 thread pitch, from any late model R, K or S Beemer.



No machining's required and they clear the inside of the fork legs by a country mile.

good find dazza

charlie99 wrote:good find dazza

It's the smallest things what brings the most joy, sometimes, Chaz.

Any grinding flat of the probably cadmium-plated original screw would invite rust or corrosion anyway. These are easily 2mm flatter than stock and are gobbed with threadlock goo. It helped to have a relatively quiet day at work, the latest ETK catalogue and several drawers full of hardware for various Beemers to compare against the originals.

Axle done.



Noice.

"It helped to have a relatively quiet day at work, the latest ETK catalogue and several drawers full of hardware for various Beemers to compare against the originals."

Like a kid in a candy store.
 
You would have to be the envy of everyone on this site!

Living the dream. I do say my thanks for the situation at times. I mean, I love motorbikes, I really dig BMWs, I have just under four hundred thousand dollars worth of new Ducati and BMW spare parts to look after for the boss, and more than a little bit of them, by some coincidental chance, fit early K bikes... Go figure.

Nice,  I wonder if they have enough mass to trigger the inductive sensor I have running my speedo.  I have hex head bolts and they look out of place.

Their flat head is about 17mm wide so they should have plenty.

Back to the brake disc screws for a mo'...



The flat, wide surface of the new screw works far better than the domed (which I'd machined down a bit) original screw. They're both the same internal length and thread dimension. There's barely 1.5mm between the fork leg's inner thigh and the domed screw and this increases to over 2mm using the flat screws. Minutiae, yes, but oh-so-important. Now there's no need to hack away at a perfectly good fork slider.

Handlebar bling...


At the perfect angle...a ProTaper 'bar of 28mm centre, tapered to 22mm (it's actually in inches but the hand controls slide onto the 'bar ends without tension, as is usually the case with a 7/8" diametre end. The 'bars fall to hand easily without an unnecessary twist of the wrist.


A 'dashpad' won't be used, and the ignition/lock cylinder flange is to be machined off. These will go elsewhere. The forks, frame, wheels and driveline are going together over the coming weekend.

If you desire a 17" five spoke front wheel from a K1200RS/GT/LT series motorbike for your earlier K with either three spoke or Y spoke wheels, these are the accurate dimensions. R1150R/RS/RT series 17" five spoke front wheels require a different dimension on one end - to be determined by me at a later date. R1150R-Rockster & R1100S wheels don't use a speedo drive so they are the same as the K12 series wheels.

20mm axle for K1200RS/GT/LT (& R1100S) 17" front wheel on K75/K100/K1100 forks using original size of bearings from the K1200RS/GT/LT/R1100S/R1150R-Rockster wheel.


Overall length is 265mm (camera angle distorts image). Turn down axle diametre to a whisker under 20mm where it passes through ID of bearings. It's essential to have a bearing, new or used, to measure inner bearing race tolerance against the axle shaft.


The 30mm end of the axle can be 75 to 80mm in length as desired for protrudence beyond the fork slider. A 10mm cross hole was drilled for the use of a 'tommy' bar for easier axle removal. Machine down axle diametre just a whisker under the fork slider's ID. Again, the camera distorts the angle.


Machine down the original 20mm non-stepped, aluminium, preload axle collar to 17.5mm. The other end's collar doesn't need to fiddled with, length-wise, at all.


No adjustment is necessary to the original 20mm stepped collar at this end. The 10x20mm screw and seat can be used as original from your early K bike.


Machine a collar of 52mm length, 30mm OD and 20mm ID to be fitted to narrow fork slider end to take up slack between axle OD and slider ID. There's no need to slice it end to end as previously thought since it is well clamped and allows sufficient tightening of the two fork pinch bolts. It can stay inside the fork slider when removing axle, but can be easily knocked out with a punch if service work is required.


Here you have a visual of the width of the fork slider end for an idea of how long the internal collar needs to be.


Here's a complete axle. It works as original with the wheels centred between the forks, 305mm discs centred in the four-piston Brembo callipers, an easy slide in with a firm push by hand to fit and no bearing clearance issues.

Dimensions once again are - overall length 265mm. 20mm x 185mm. 75 to 80mm x 30mm OD stepped end. 17.5mm original aluminum collar length. 52mm x 30mm OD x 20mm ID fork slider collar. No adjustment made to stepped collar. Drill 10mm cross hole for removal tool then tap 20mm deep for the original 10mm end screw.

Th'th'th'that's all, folks!

It's a lonely job, but someone has to do it.

Makin' progress.

She's about a roller.



I'm putting her together loosely...see how it all fits, then stripping it back for paint, powdercoat and fine detail. The K1200RS 5X17 rear wheel clears the Paralever swingarm using the stock 2mm spacer with about 3 or 4mm to spare - plenty. The 170mm Metzeler ME880 on the rim is just there to move the bike about. A set of Pirelli Diablo Rosso II are waiting in the wings. They are sizes 120/60ZR17 and 170/60ZR17. The bike sits low and the riding position feels neutral, with just a slight lean forward. The rear shockie I'm having made will be length-adjustable. The front mudguard will be trimmed and slimmed and painted not red. Sorry, Blakey!

Here, in the red oval, the frame will be cut and lifted, then tapered to suit the (BMW F800S) seat's shape. At the front the seat will be shaped to fit up against the back of the tank and wrap around it as well, just so.