Things'd have to be serious before I disturbed anyone's sleep. Get studying those eyelids!

Ref. the alternator - nope, it was all perfectly clear after I read your posts. Cheers.

Bike now modified to travel everywhere by railway line, per the miniscule steering lock as is traditional with cafe racers/clip-ons/Avon fairings.

Love the photo Chris - looking very cool indeed but I miss the "Make Life A Ride" mug strategically positioned in many of your early photos of this build.  We are getting closer to your first ride report and I'm really looking forward to see what you feel about the many design decisions you have made along the way.

"Many design decisions"

C'mon, that makes it sound as though this thing was thought out. You've seen the sticky tape and stuff!

The bike is really only about cutting and shutting the frame to match the missing 78mm that was taken out of the '100 engine to make the '75. The rest of the girly cafe racer/poncey silver frame is just copybook show-off stuff!

Cheers though, and yes it should be ridden soon.

Edit:never noticed the logo on the mug! it's just what my mate brings me coffee in. I'll try and track it down.

Well after a near enough five month hiatus (time seems to fly in the latter part of your sixth decade, or maybe I'm just not paying attention to stuff anymore) things have started rolling again. Loom and paint is all that's left to do. Here's the loom, slowly growing like knotweed over the bike:



And here's one of the reasons for the hiatus:

Name's not Larry, is it?

Cute little Hiatus, You planning on using a K1100 tank by the look of those frame tops? That's 1994 onwards dual top tube formula.

Well I'm chuffed that Larry-the-Hiatus showed an instant interest in getting hold of my hand tools. In order of preference: hand axe, cordless screwdriver, hammer. I've had to ban the wood chisels; even I have limits. In the pic he's cleaning the outside of the house, with the car-washing brush...

Top frame - yep, ihe thing was made from two K1100 frames, because of the steeper rake/head angle that the K1100s have over the K100/K75. Probably make no difference to the finished item whatsoever  

  Wait till he gets the Autosol onto the roof and guttering

Suddenly got guiding light again with this one, can't wait to prod that starter button.

Bearing in mind this is/was just about a wreck of an engine, bought for fifty quid from under some guy's bench where it had done nothing for years. Strip down indicated a lot of previous poor workmanship, worn cam, mad valve clearances, and a seized/wrongly assembled big end, topped off with an asthmatic oil pick-up. I rebuilt it within my abilities/financial indifference, and fitted it with a nonsense intake system and a straight through exhaust, plus a make-it-up-as-you-listen-to-the-radio wiring loom and a motley gathering of injectors, ECUs etc etc

...dare I video the attempted start up/explosion/fire?

YES of corse

Yes, but yours started...

Personally, I need some stimulation these days since all the local watering holes are shuttered.  A few explosions and a lot of smoke would go a long way toward satisfying that need.

Yep we wanna see if it goes Zip when it moved and Bop when it stops and Whirr when it stands still. We'll never know if you don't dare and press that starter button.

Things to do in lockdown when you're bored...

Well the workshop, and the project, are at my mate's house a couple of minutes walk away. With this lockdown I can't really justify tripping up there just to finish the wiring loom, so to keep my K mojo spinning, I've been finding things to fiddle with in my shed.

These are some over-the-top bezels that will mount a couple of warning lamps into those big, convenient holes in the KTM top yoke:


And here's some end caps to smarten up a couple of refurbished gear position senders - I'll seal them with RTV and they should look a lot smarter* than the bodged up items that I normally turn out.


*Yep, 'cos they're really on show on the assembled bike aren't they 

As forewarned Chris, the following is my thread hijack....

Since my own project is coming along nicely - parts on every flat surface, hung on the wall, some of it bagged and labeled, some of it not and some of it even spilling over into my (wife's) living space - I thought it time to hit you up for specifics on your air box mod.  Nothing against the OEM unit which came on my K75 but yours is so very elegant and trick looking and efficiently using a discrete amount of space that I decided I need one just like it. For a nano second I thought to reverse engineer it but the slovenly part of me overruled that thought and compelled me to hit you up for your knowledge and guidance instead.

How did you make it?  What parts did you have to purchase?  Anything you would do differently on a 'version 3' release?

Cheers,  Woodie

Hiya Woodie and thanks for the interest.
I'll be doing a grocery delivery tomorrow (groceries for the workshop owner), so I can photograph some airbox leftovers to give you an idea.
As with most of my stuff, it was minimum expenditure and maximum messing about. Oh, and dubious benefit too  

Well here's a couple of pics showing the airbox in situ - to help you make your mind up if it's what you want/worth all the work. This is the K75k remember - the airbox was firstly made for the Madass, because the new frame didn't allow fitment of the OE airbox, so it was a needs must affair. The K75k on the other hand has a 'normal' frame so the daft airbox just isn't necessary at all. I just liked the look of it, no other justification.

Unless, for some reason you need to mount the Jetronic ECU under the frame beneath the tank as I have done in the pictures. This was just a convenient place to put it, after it was evicted from its normal abode to make room for the battery. So, the pictures show how there's room to do this, and still leave plenty of daylight above the engine/beneath the frame. 




I should make the point that neither the K75k nor the Madass have a cooling fan. So the airbox wasn't designed to clear one. Having said that I do think clearance wouldn't be an issue, but I could check with a spare fan? Note also that the FPR is relocated onto one of the frame downtubes to allow the airbox to sit right up next to the throttle bodies.

The next pics are just general views of the airbox fitted. The view of the left side shows the fuel return hose to the FPR - the side of the airbox was just a convenient place to clamp it. The 16v throttle cable bracket (and cable quadrant) isn't completely necessary, I just preferred the cable routing that it allows.



Next up is the airbox removed. Note the tops of the throttle bodies - they have been smoothed to allow the elbows to slide on (quick job with a file and then a scotchbrite wheel)


This next pic shows the AFM removed. The AFM outlet stub slides into a bore in the side of the airbox, which is fitted with an O-ring seal (hence the red rubber grease everywhere!). The airbox side just happened to fit into the 4-jaw of my lathe which allowed me to machine the bore and the groove for the O-ring. The AFM is a good secure fit and this method provides its main support and mounting. Note also the radiator hose (the thermostat bypass hose) passing across the front of the airbox - this explains the concave indentation on the front.


These 3 pics show the other means of mounting the AFM and securing it in place. It's a bit simple and consists of a bobbin screwed into a convenient threaded hole in the top of the engine block, with a corresponding radius filed into the AFM flange as a location. There's also a rubber support (the bottom half of a cut down M8 rubber bobbin/isolation mount) screwed into another convenient hole - 3rd pic. A bit unglamorous, bit is seems to work (but nowhere near as well as the OE setup! oh well) The 3rd pic also shows the sole screwed mounting for the airbox - a tang on the base to pick up another convenient threaded hole in the engine block. 




This pic shows the rear of the airbox, which fits closely over the contours of the engine block. The rear-facing 'nose' is necessary to accommodate the inlet runner for cyl no. 3.


Here's some general pics of the airbox showing its construction. Basically, the sides and base are shaped from 12mm black nylon plate, and screwed together with M4 cap screws. The skin is 1.0mm aloominum sheet, carefully folded and riveted in place. All sealed with tigerseal before assembly.




Now for some plumbing. The elbows started life as cheapo PVC solvent weld plumbing fittings. The one in the bottom of the pic has been modified in the lathe: turned down and shortened at one end to match the larger of the two diameters of one of the rubber boots nicked from the top of a standard throttle body (on the left of the pic) and bored out and o-ringed at the other end so's it will slide snugly over the top of a throttle body. A bit tricky to hold in the 4-jaw, but PVC is easy enough to machine once you've got it held square (ish!)


The next pic shows how it all cobbles together: The turned-down end of the elbow fits into the top of the rubber boot (once you've removed it from the grotty throttle body) and the rubber boot then slides over....
....actually you can't see it. Inside the airbox are three inlet runners nicked from a K1100/16v airbox. They just happen to be the right diameter, and they're straight, unlike the 8-valve ones. I shortened them by about 30mm or so, so's the total runner length was something like the total runner length on an unmolested K75. 
3 holes were bored in the airbox side to be a snug fit on the K1100 runners, which were sealed in place (tigerseal again) and fitted with just enough protrusion to suit the stepped inner dimensions of the rubber boots, which were then slipped on to them.
I've just noticed that I've forgotten to install the stainless clips on these.


Here's a not very good pic trying to show the inlet runners inside the airbox

Oh, I forgot your last question.

'Version 3' is a Microsquirt and 3 cone filters!

Would you be offended if I asked you to remove the air box, drill out all the rivets and give me a peek inside?  I know I would be if someone were to be dumb enough to ask.     

This is fantastic Chris, thank you for taking the time to document everything.  I will have a go at building this - after I spend the requisite time cleaning the beast.  My shop is filled with the stink of old gas (and not mine, wonder of wonders) after having broken the bike down into its many constituent parts last weekend.  I brought home a gallon of degreaser which will be put to good use tonight and hopefully will begin fabricating the new bits soon.

Cheers,  Woodie

Nah, but I'm not going to do it - the tigerseal's too good!

I'm sure I've got at least one spare K1100 intake runner/trumpet kicking around somewhere that I can photograph. In the absence of a functional memory, I've reasoned that: A I've used six trumpets on two bikes, B I must have acquired at least 2 K1100 airboxes to do this, C K1100s all come with 4 cylinders, D 2x4-6=2 left over. There's one more place to look, which is at the bottom of everything I own. It's always good to do this, because I invariably come across loads of useful stuff that I've no idea I've got!

I can easily post some dimensions, O-ring sizes etc. The nylon sheet is really versatile stuff but it can be a bugger to machine if tools aren't sharp (it rubs, quickly overheats, melts and gives a poor finish) I found that the 12mm stuff was thin enough to bandsaw at a slow and steady speed, and you can finish it up on a miller (as I did) or, surprisingly, on a small bench linisher (as I found out afterwards)

The inside faces of the nylon sides and base (which you can't see cos I'm not taking it to bits!) are actually milled out to lighten it and slightly increase the volume, just leaving full width around the inlets and outlet for the O-ring fitment. I don't think I'd bother doing this again, because the removal of material allowed the nylon sides to creep and deform a little.

An alternative construction would be entirely of aloominum or 2mm nylon/ABS/your favourite engineering plastic, sealed and rivetted to ally angle section for the corners. You could then turn up flanged adaptors for the inlets and outlets and seal these to the thin sidewalls with tigerseal. You'd have to be creative if you wanted curves on the outer profile of the airbox though.

I'd say it was an enjoyable job to do, kind of kids' stuff creative, and it's really 'only' an airbox - what can go wrong!

Chris, a mate showed me a trick when machining plastics. Probably one of the few uses for WD40, spray it onto your cutting tool and it keeps the plastic from sticking on the tool and back onto the job.
Regards Martin.

I bet that would work well on the bandsaw blade..
cheers 

"An alternative construction would be entirely of aloominum or 2mm nylon/ABS/your favourite engineering plastic, sealed and rivetted to ally angle section for the corners. You could then turn up flanged adaptors for the inlets and outlets and seal these to the thin sidewalls with tigerseal."


This might well be the route that I take as I don't have the nylon squirreled away out in the shop.  I'll definitely be trying the WD40 next time I'm working with plastic as well.

chris846 wrote:I bet that would work well on the bandsaw blade..
cheers 

I use it on mine, sparingly. I’ve never set the drive wheel spinning against the blade but do worry that I might.

One question for you Chris:  what became of the Z tube/crankcase breather?

It just vents to atmosphere - like in the olden days

Wide open to the elements or with a cap similar to the one on the transmission?

Cheers!

I think a Lucas rubber boot (for the ht lead onto a coil) fits snugly onto the crankcase stub, then some rubber tube down to the somewhere near the sidestand - or into a beer can if you're desperately cool. The can isn't necessary though, almost nothing comes out of the breather unless your engine's poorly.

Awesome Chris, thank you.  I now have a plan for a mystery drain tube that I found on the K75 which I don't have on the K100.  If I don't use the tube then I will perhaps use a whiskey flask.  I'd go with the beer can but I think BMW's require more refinement than that.  

It’s a tough job, this custom bike building. The colour is a VW bug colour from the sixties: ‘VW Gulf Blue, With Flies’.

EDIT: using new windows 10 PC & the photo I wanted to add is on my Iphone, totally forgot that Apple & Microsoft conduct this ongoing battle for total ownership of our minds and lives...
Edit2: here’s the pic, finally

Managed to polish the flies out. Golly the paint dries quickly in this sun.

Paint looks great Chris. Sorry the avi still scares the wits out of me .

Whatcha using for paint Chris? Acrylic 2K or (say it quietly) cellulose?

Very very quietly!

...Well I thought; seeing as it's a 1960's colour, I could use 1960's paint. It means a twit like me can keep sanding and painting, and sanding and painting, and sanding, and painting, until the flies get fed up of landing on it.

Being a 'modern' cellulose, it seemed to dry really quickly - either that or the 24 degrees sunshine burning through a sky devoid of jet fuel meant that I could chuck the paint on this morning and set about it with a machine polisher this afternoon. It's far far from perfect, but it's damn good for rattle cans.

EDIT; Is an avi an avatar? Not everyone is lucky enough to get wrinkles.

Was slightly perplexed to receive a consignment of steel wire armoured cable..
..wrapped in ‘FRAGILE’ tape. Hmmm



(Still part of the build thread - just - I’m rewiring the garden in between waiting for paint coats to dry)

With all that cabling, looks like you are going to rival Blackpool    

Mike

There's an oddity in UK law (specifically DEFRA) that states if a vehicle is classed as Classic, Vintage or Veteran then you can use cellulose paint on it, otherwise it has to be acrylic. However, there is no official definition of Classic, Vintage or Veteran - that seems to be down to what the insurance companies decide between themselves.

Talking of which, Carole Nash now classify any bike over thirty years old as vintage and 20-30 years old as classic Have no idea if that's going to affect my insurance renewal next year.

That means every one of my bikes is either classic, or vintage. I don't really mind, but I'm not sure that I'm ready to feel like this fella!


BTW, I didn't realise that celly paint was actually banned - I thought it was unpopular with the pros cos' it was rubbish! Thanks for the tip.

Every time I see a picture of an AJS 350 G5 I want to see the registration plate to see if it's the one I had on loan many decades ago. It was so much FUN riding that bike!!!


Actually, come to think of it, I can't remember the registration any more

chris846 wrote:Managed to polish the flies out. Golly the paint dries quickly in this sun.

Chris, followed your lead and gave the sidecar a quick refresh in the sunshine, what polish did you use to shine that top coat? Come to that what is the mop on that grinder.

The mop is a soft sponge, and I used some cheapo scratch remover as a cutting compound. I wasn't expecting much but it turned out alright and so I've ordered some Farecla cutting compound. The trick with these polishers it keep it slow, and stay away from the edges. There is a bit of a knack but it's not hard to learn, definitely worth the investment.

What I like about it is that it doesn't use the disk on top so you can use the face, which is also what I need to mirror my tank.

Not sure whether you've already got a polisher, or if you're thinking of getting one. But, the one I have is a bottom-end Silverline brand which does 600-3000 rpm. I use it the lowest speed, with the softest grade of sponge mop. The risk with these things is overheating the paint, which then softens and cuts through almost in an instant. That sounds scary, but if you keep it on the slow speed and keep it always moving over the paint, things are safe enough. Polishing 'on' to an edge is too risky, but polishing 'off' an edge with light pressure is okay. A lot of this is kidology - just polish the big, obvious areas and your mind will see what it wants to see i.e. a lovely shiny job - you don't have to do too much in the tricky corners and areas.

Of course it was all easy enough on celly paint - there's no lacquer topcoat to worry about cutting through. And, if you cut too much paint away then, being celly, you can always spray some more on and start cutting again, yeehah.

Not sure if this would work too well on DIY 2 pack. If your basecoat is rough, then there's no way that you could overcome this by polishing the lacquer topcoat.

- that's not to say it isn't successful on professionally-applied 2 pack though. I have a weary-looking Honda CR-v with ten year old black paint. The polisher did a great job on that recently with just Autoglym standard polish.

Clearly I'm an amateur idiot, so if any of the above makes you wince....disregard 

Thanks Chris that’s a useful sense check for me.
I assumed that was an angle grinder (which I have) and was wondering how you kept the sponge speed down.
TBH my original intention was to just black out a tacky looking red strip around the chair and cheer it all up a bit.
I got carried away as always and thought it looked so nice with minimal prep that I might go back and do some sanding and filling and make a proper job of it.
But actually I’m happy with OK and will just add some protective wax by hand.
Would rather spend the time and money on reliability/usability than glam.

Cutting compound, then polishing compound, then t-cut.

Or in the old days, 1000 grit, 1500 grit, 2000 grit, then t-cut, followed by a new pair of fingers.

I've painted four bricks so far, and used 1K acrylic enamel base with 1K and 2K clearcoats, mostly from rattle cans.

I use a cheap Harbor Freight DA orbital buffer with a set of 3" foam pads to apply 3M Perfect-It #2 and #3 after wet sanding from 1200 t0 2500. 

I run a bit higher than the lowest speed, but keep the pad moving over the surface.  Moving quickly with light pressure gives the most uniform results.  Perfect-It works pretty well on almost everything.  I've even used it successfully on urethane clears.  The only stuff that it doesn't seem to work on is the seriously hard industrial stuff like Awlgrip and Imron non-clearcoat systems.

Edges aren't too much of a problem.  I keep the machinery away from them, and just do a light hand polish to knock down the worst of any orange peel.  When putting the clear on, I consciously try to put more on the edges.  Besides adding protection from buffing through, the extra clear helps the orange peel flow out.

it doesn't always work out.
I've just spent this afternoon painting the front mudguard. I got as far as the filler primer over etch primer, and it all started crazing through. Turns out someone else has painted it before, oops. Sanding and more primer was the wrong choice. So after that I reached for the acetone, and I would have photographed the sticky gooey melted mess that I created, except my hands, and pretty much everything else in this part of the world were stuck to everything else with yeuch. You'll just have to imagine it.
Tomorrow is another day