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1Back to top Go down   K75 Madass Empty K75 Madass on Tue Nov 14, 2017 6:17 pm

chris846

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Well it wouldn't be my choice of a name, but it worked for Sachs...

Hi, I posted in the introductions section about a K75 project. Here's some more detail:

K75 Madass Madass10

I came across two of these in a dealers a few years ago when a pal was having a tyre changed. I thought they looked great. Always had a mind to get one for fun. Thing is, they're not brilliant quality and they seem to be silly expensive for a pumped-up step-thru (it's a honda cub/C90 in beachwear).

Sooo, when I retired and needed a project (having rebuilt my K100 for the umpteenth time after yet another prang) I had a daft idea to see if I could make a Madass out of God's own motorbike - a 'K'...

Pretty soon it started to get Not Daft, there seemed to be a few serendipitous aspects to taking a K in this direction. Here's the sum total of the extensive computer modelling, ahem...

K75 Madass K75_7511

Basically, when BMW conceived the K75 they left out the front cylinder and bent the front frame legs back (it says this in a book I've got!). I thought I'd shunt the K75 engine forward back up to the front wheel, because this would make room for the line of the frame/petrol tank as it skimmed the top of the bellhousing. Turns out this 'making room' would also even up the weight distribution (the finished bike is 103 kg front/102 kg rear), shorten the wheelbase (I moved the rear wheel forward by 25mm) and lengthen the K's swingarm (I decided on a highly-technical 50mm for the extension, because that was the size of ally billet I'd got to make a spacer - us shed-builders know how to deal with tricky decisions). I have a thing about the K's stubby swingarm anyway, all that jacking up of the back end can unload the rear wheel half way round a bend - if you're daft enough to overdo the rear preload and cane it with just 10mm of static sag...but that's another story (and rebuild, as it happened)

Never mind all this pseudo insight, the extra gap between the rear wheel and the swingarm front means I can have a Ducati style underseat exhaust! that's what really counts!

Now where's the hacksaw?

chris



Last edited by chris846 on Wed Nov 15, 2017 3:46 pm; edited 1 time in total (Reason for editing : it was wrong...)

    

2Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 12:59 am

charlie99

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K75 Madass 723598


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75 Madass Au-log10
    

3Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 2:52 am

chris846

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Hi-level computer modelling and analysis is all well and good (okay, Microsoft Paint) but it was time to move this technological breakthrough into the state of the art 3d modelling facility that I bought at Batman's garage sale. I skipped the consumer research stage on the fairly solid grounds that my mates said that it was a s***t idea, and why didn't I build a proper bike anyway?

K75 Madass 01412

...early versions considered a revolutionary means of attaching the wheels to the frame by invisible force field. This was soon binned on the grounds that I have absolutely no idea how to achieve this, and it's probably impossible anyway. Other ideas under consideration were the use of A: Propane or B: electricity as a fuel. These were also discounted on the grounds that A: the propane bottle was empty and B: the electric flex wasn't going to be long enough.

    

4Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 2:57 am

charlie99

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K75 Madass 44271


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75 Madass Au-log10
    

5Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 3:10 am

chris846

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Hi Charlie99, I think I'm going to need your skills on this one. Actually, anyone with any skills would be useful..

    

6Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 3:21 am

chris846

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Close up view of the difficult bit, showing what can achieved with laser cutting, 3d printing...and No.12 woodscrews:

K75 Madass 01911
Replacing the battery with a cardboard equivalent offered some great weight-saving advantages, but it was difficult to get it to hold any volts. We took the cat food out first.

That engine was REALLY grimy. The fact that I hadn't bothered to clean it first, belies my actual lack of belief at that stage.



Last edited by chris846 on Wed Nov 15, 2017 3:48 pm; edited 3 times in total (Reason for editing : grammar)

    

7Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 3:48 am

charlie99

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fell off ma chair chris ...your phrasing of the technical merits is making me giggle way to much to be serious ..."3d printing...and No.12 woodscrews:"


but if I can contribute ...please ask away

btw ...love the paint caps over the throttle bodies inlets ...well perhaps  one and a half of them ...grin


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK75 Madass Au-log10
    

8Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 8:56 am

Dai

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@chris846 wrote:Replacing the battery with a cardboard equivalent offered some great weight-saving advantages, but it was difficult to get it to hold any volts. We took the cat food out first.
I see you believe in buying in bulk too...

This is just my sense of humour. Keep going!


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

9Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 3:21 pm

chris846

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Yep, the paint caps, not even a matching set..

After several weeks of heavy duty ebaying, here's how it was looking:

K75 Madass 05911
By this stage I'd settled on 2 parallel 3 1/2" steel tubes for the main frame/tank, and good old 4x2" box for the bit above the gearbox - I suppose you'd call it a yoke. This stuff is lying all over the ground in a stockholders yard near where I live, nothing fancy in this neck of the woods! My fabrication 'skills' come from a lifetime (I hope) friendship with a former maintenance fitter at the Coal Board, so it's all Big And Strong (no cutting corners underground!). Downside is the weight, but I do have a half-plan to remake the frame/tank in ally if it turns out not to be a complete disaster (I have absolutely no idea how to make something like this in ally). 

The wheels are 16v KRS, another bit of serendipity because they are 3 spoke like the Sachs and, like the Sachs, the rear is bigger than the front (18" rear/low profile on the 16v KRS).

The forks, yokes, bars and front mudguard are KTM 640 Duke. I think I chose them because A: they keep the front end tall, and B: they were cheap on ebay (mainly 'B'). The steering head was made from scratch to suit the KTM stem/bearings. Here's the CAD department busy at work (do they still have CAD?, has it been seen this century?)
K75 Madass 00112
Note the happy mixture of metric and imperial dimensions, and the over-reliance on scribble.

The front calipers are F800 - definitely not Brembo. This is because F800 calipers seem to be a lot cheaper than Brembo calipers on ebay.... Funny though, they do look like Brembo P4 65mm. The front discs are 320mm from a R1100s, mainly because A: they were in the drawer (there is no B).

    

10Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 3:24 pm

chris846

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Around about this stage, BMW's head of design called in to have a look...

K75 Madass 06810

    

11Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 4:00 pm

chris846

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I never thought I'd see a German cry. He was so happy, and really nice. Before he left he said:

"Sie und ihre idiotischer freund sind in Deutschland nicht willkommen"

Which I think was a lovely invitation (my German isn't great).

    

12Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 5:33 pm

Gaz

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Absolutely love the project Chris from many perspectives.

Your design studio CAD looks just like the output from mine,
The design is heavily based around the choice of materials available i.e. scrap,
The computer modelling direct approach i.e. clamp up some chunks of timber in place and walk around it a few times.

Keep up the good work!

Cheers


__________________________________________________
Gaz
1990 K75 6427509; 1987 R80G/S PD 6292136; 2010 G650GS ZW13381; 95 K1100LT 0232224
    

13Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 5:47 pm

Dai

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@chris846 wrote:Note the happy mixture of metric and imperial dimensions
Oof - been there, done that. I always remember measuring up for some particularly critical piece of hardware on our dive boat and the answer came out at 'six inches plus a centimeter'.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

14Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 15, 2017 5:49 pm

chris846

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Cheers for the replies fellas, I knew I wasn't the only one with this approach!


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The Longest Lunch
    

15Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Nov 16, 2017 5:24 am

chris846

chris846
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Re. the front discs. It would have been way too easy to use the discs that were designed for the wheel. It would also have been sensible. That meant it was never likely to happen. I have a R1100s, so that's the reason there were some discs knocking around (it's great living just over the hill from Motorworks). So, time to fire up the CAD system again:
K75 Madass 00114
The sharp-eyed might at this stage start to be worried - the casually scribbled out "t=4", replaced with "t=5" might indicate someone who hasn't either: A, a clue, or B, any wit or regard for braking design. This would be a fair observation. Fortunately the same design (as ever I use the word in its loosest sense) seems to be one of the few things that I haven't so far managed to break on this:
K75 Madass 05710

    

16Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Nov 16, 2017 5:59 am

92KK 84WW Olaf

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Chris

Its a great thread with the right amount of humour and wit appropriate to an analogue CAD department.

I just hope when you were mocking it up that it never gave the feeling that it wooden work.

But it does and to be honest I do think when [see, not a pessimist saying 'if'] you get it competed its worth remaking in alloy!

All Ks should have a Kat- My cat sleeps on my K [well 1 cat on each K] and has the seat prewarmed for me when I take it out. Its a very useful feature and even better doesn't add weight.

We might even send you a Christmas pudding!!


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

17Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Nov 16, 2017 11:41 am

jbt

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Good idea, I like it.
But the main issue you'll have to cope with is the place of the air filter box and its flowmeter...

    

18Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Nov 16, 2017 1:44 pm

92KK 84WW Olaf

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@Dai wrote:
@chris846 wrote:Note the happy mixture of metric and imperial dimensions
Oof - been there, done that. I always remember measuring up for some particularly critical piece of hardware on our dive boat and the answer came out at 'six inches plus a centimeter'.

Sounds a bit like an Airbus......wings made in imperial land and other parts made in metric land. Now we finally know how they are mated.

So what happens after brexit? Airbus take to making rockets?


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

19Back to top Go down   K75 Madass Empty Re: K75 Madass on Sat Nov 18, 2017 5:00 am

chris846

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"Wooden work" - ouch!

JBT you called it - by trying to keep the frame line as close as possible to the 'headstock-swingarm pivot' line, some sacrifices were called for. This wasn't the odd lamb and a couple of stringy calves either, oh no, this was full blown Mayans-getting-pissed-and-throwing-all-the-virgins-in-the-volcano type sacrifices.

K75 Madass 01710
The 'important frame line' and the alternator had a battle for the same space. The alternator lost and joined the plenum chamber in the box marked 'nah, we can live without this'.

Much more worryingly, the top bellhousing mount went the same way....

Now I'm open to any views on this, but I convinced myself that the frame takes its strength from the CDS, not the other way round. The remaining four mounting points seem enough for the job, and the oddball (see how I'm subtly dismissing it already) assymetric top mount -might- have been to stabilise the frame against the forces from the rear suspension top mount. And -maybe- to offer some triangulation to the parallelogram shape of the front part of the frame, neither of which were needed on the Bike Of Doom.

Phew, almost convinced. if anyone is feeling nauseous with worry at this point, that's okay, I understand. Here's another picture:
K75 Madass 02011
The frame in this picture went to Jesus, but the engine/bellhousing/gearbox - all the CDS, all lived another day. I looked at this and thought, "nope, that CDS doesn't need to ask for any strength, from anything" (the tree survived btw, trees always do)

If you can zoom in you can make out the remains of the Jetronic ECU. I say remains - I rivetted the cover back together and it still worked. These are all reasons why I love these tough old Ks.

    

20Back to top Go down   K75 Madass Empty Re: K75 Madass on Sat Nov 18, 2017 8:24 am

chris846

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Here's another picture of the decapitated bellhousing:
K75 Madass 01912
It shows the soozooki alternator (small and cheap) on the made-up mounting that uses the old battery tray mounting holes - the 2 on the right side were tapped out to M8. I think the 5mm section angle for the battery tray base is a bit over the top, but it's part of the whole alternator bracket that I didn't want falling to bits. The original cush drive cup was kept and grafted onto an extension shaft, so that the alternator could go rearwards enough to clear the underside of the frame 'yoke'. The alternator came with its own cush drive flange still on the front, so I used that too. Its super-cushioned.

The picture also shows the alteration to the clutch release arm. This was another frame-related sacrifice: the rear left mounting on the frame obscured the clutch cable slot in the gearbox casting, so a new cable bracket was made that bolts onto the two holes you can see on the battery tray.

    

21Back to top Go down   K75 Madass Empty Re: K75 Madass on Sat Nov 18, 2017 2:47 pm

Dai

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I know someone in Norfolk who does things 'just because he can' too. Shocked Shocked


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

22Back to top Go down   K75 Madass Empty Re: K75 Madass on Sat Nov 18, 2017 3:02 pm

chris846

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Here's the clutch cable bracket - and the 'Ducati' routed exhaust!

K75 Madass 01310
And here's a couple showing the missing bellhousing mounting:
K75 Madass 00710
K75 Madass 00810

    

23Back to top Go down   K75 Madass Empty Re: K75 Madass on Sat Nov 18, 2017 3:03 pm

chris846

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Heyup Dai, what's your honest view on the missing bellhousing mounting - it it going to fall in two at the first wheelie?

    

24Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 3:58 pm

92KK 84WW Olaf

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I had a thought on the bell housing...will K1200 fit your set up? It fits the K100/K1100 but it has different mountings because of the frame change from K100/K1100 to the K1200.

I have a feeling the K100 gearbox will swap over too, will need someone more knowledgeable to tell me if I'm right.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

25Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 4:09 pm

Motorbike Mike

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@92KK 84WW Olaf wrote:I had a thought on the bell housing...will K1200 fit your set up? It fits the K100/K1100 but it has different mountings because of the frame change from K100/K1100 to the K1200.

I have a feeling the K100 gearbox will swap over too, will need someone more knowledgeable to tell me if I'm right.
Good point Olaf but I wonder if the K12 bellhousing was fitted, why not fit the six speed gearbox? 
I've just sold a K12 g'box so can't check but does the k12 output shaft connect to the K100 shaft? if you're building a frame from scratch the six speed box should be a consideration.

    

26Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 6:02 pm

92KK 84WW Olaf

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@Motorbike Mike wrote:
@92KK 84WW Olaf wrote:I had a thought on the bell housing...will K1200 fit your set up? It fits the K100/K1100 but it has different mountings because of the frame change from K100/K1100 to the K1200.

I have a feeling the K100 gearbox will swap over too, will need someone more knowledgeable to tell me if I'm right.
Good point Olaf but I wonder if the K12 bellhousing was fitted, why not fit the six speed gearbox? 
I've just sold a K12 g'box so can't check but does the k12 output shaft connect to the K100 shaft? if you're building a frame from scratch the six speed box should be a consideration.

The 6 speed gearbox does fit.....the only way to fit that to the K100 is to use the K1200 bell housing. Elsewhere on this forum.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

27Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 6:07 pm

chris846

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That's interesting. I have a K1100 paralever swingarm and bevel box, which I was thinking about using if I could find a suitable gearbox with the mountings for the torque arm - I was thinking the gearbox would be from a K1100, or a K100RS 16V.
I never thought about the K1200 box and a bellhousing to go with it - would they fit a K100 engine block?
The other thing that's really interesting, is whether or not the K1200 has a top bellhousing/frame mounting? If it doesn't, and the K1200 just uses the two front engine mounting bolts, plus the two gearbox mounting bolts, then maybe this means the CDS can get by without the fifth bolt and the Bike Of Doom isn't going to fall in half at the first wheelie?

Edit- just read Olaf's post - the K1200 bellhousing does fit a K100, yay!

    

28Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 6:27 pm

Dai

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@chris846 wrote:Heyup Dai, what's your honest view on the missing bellhousing mounting - it it going to fall in two at the first wheelie?
With that ther frame, you got no problem!


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

29Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 7:14 pm

92KK 84WW Olaf

92KK 84WW Olaf
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The K75/K100/K1100 frames are all steel tubular and the mountings are similar throughout these bikes. K75 down tubes differ to suit the shorter engine but gearbox ends etc are all the same.

The K1200 changed frame type and the bell housing has different mountings [I think] to suit this rather than the single one in the centre to suit the K75/K100/K1100.

Not sure what mountings are on the bell housing or the gearbox [presumably gearbox is same as 5 speed gearbox with 2 mounts] because those who looked into this on the forum have said the 6 speed gearbox would fit but had to have the K1200 bell housing.  Which is why we do not have half the forum putting 6 speed gearboxes on their Ks. The K1200 bell housing mountings don't work with the K75/K100/K1100 frame set up only because of that mounting. But you are not stuck with that so look a little more.

A 16v gearbox K100 16v/K1100 has the torque arm mountings you need and are a straight bolt on job.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

30Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 7:59 pm

RicK G

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All the gearbox casings made after about may 1990 had the tags for the anchor arm but were not drilled. If you do get one of these cases and need to drill the hole it is important to get the hole in the correct place or you lose the parallel component of the paralever, it is also worth noting that the alloy is VERY tough and you will need to mount the case in a drill press to get an accurate hole, just using a hand held drill will let the hole run off centre if it's not held square.
The alloy has a very high content of bismuth and silicon and is then heat treated and it IS tough.


__________________________________________________
"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats."  from Mencken's 1919 Prejudices

Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

31Back to top Go down   K75 Madass Empty Re: K75 Madass on Sun Nov 19, 2017 11:31 pm

Two Wheels Better

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Sheez, you go away for a coupla weeks and this is what you come back to.

Charlie, you may recall that Liz's kid had a Madass down in Banora Point. I always thought they'd make a good donor frame for a larger capacity engine. Someone else did as well.

K75 Madass Sachsm10


__________________________________________________

1987 K100RS, '89 K100 w/K1100RS engine, '93 Framed K11/K12 engine 'Big Block', '96 K1100RS, '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

32Back to top Go down   K75 Madass Empty Re: K75 Madass on Mon Nov 20, 2017 1:18 pm

Motorbike Mike

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I've just had a thought relating to the use of a K12 gearbox.
Any frame used would need to be built to hold the swing arm pivot as the K12 frame supports the swing arm. On a normal steel framed K the gearbox holds the swingarm.
Sorry if I've mislead anyone. Embarassed

Here's a 1200 gearbox I've just sold-no mounting points for the swing arm.
K75 Madass Cimg4013

    

33Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 4:59 pm

chris846

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Ah, no swingarm pivots of course. I think the K1200 swingarm/paralever must also be different because the gearbox is shorter? and so the swingarm is longer - is the K1200 wheelbase longer than the K100?. I was after a slightly shorter wheelbase (25mm) which I got by moving the K75 engine forward 75mm so's it had the same relationship to the front wheel as the K100, and then adding this 50mm spacer:
K75 Madass 00910

 - I think - the overall wheelbase must now be 25mm shorter than the K100/K75, plus it's got a longer swingarm so, maybe, no more crashing for me....

Anyway, here's a couple of pictures of the frame when I took it for welding. It hadn't got the the seat rails on at that point, I wanted a pro welding job on the main fuel tank section (way beyond my abilities) The main tubes were fully welded to the headstock at the front, and the yoke at the rear, and then the top and bottom were plated in to make an oval section main frame/tank. the LH side of the yoke is also part of the tank and you can see the threaded fuel outlet on the second picture. The welders did such a great job that, when I tacked the seat rails in place I couldn't bear to disfigure their handiwork with mine and so it went back to them for the rest of the welding too.
K75 Madass 08610
K75 Madass 09010

The finished frame looks like a big tuning fork to me. This means that when I get to 88mph it'll probably start a massive resonance at F sharp or whatever, all the bolts will immediately unscrew and my head will explode with the sonic shock wave, or something.

    

34Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 5:02 pm

chris846

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@RicK G wrote:All the gearbox casings made after about may 1990 had the tags for the anchor arm but were not drilled. If you do get one of these cases and need to drill the hole it is important to get the hole in the correct place or you lose the parallel component of the paralever, it is also worth noting that the alloy is VERY tough and you will need to mount the case in a drill press to get an accurate hole, just using a hand held drill will let the hole run off centre if it's not held square.
The alloy has a very high content of bismuth and silicon and is then heat treated and it IS tough.

That's really useful, thankyou. I've seen some gearboxes on ebay that seem to have the lugs on, but no holes, cheers.

    

35Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 5:23 pm

chris846

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Hi Two Wheels Better

Your pic is a prototype bike (sorry if you know this) of the Sachs Madass 500, which used the 500cc single engine from a Royal Enfield India (why on earth...?). I thought it had nowhere near the visual appeal of the original Madass 125/150. It was by looking at what was 'wrong' on this bike (the 500) that made me want the get the lines of the Bike Of Doom close to the original, hence the big list of sacrifices along the way (airbox, bellhousing, alternator)

    

36Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 5:35 pm

Motorbike Mike

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@chris846 wrote:Ah, no swingarm pivots of course. I think the K1200 swingarm/paralever must also be different because the gearbox is shorter? and so the swingarm is longer - is the K1200 wheelbase longer than the K100?. I was after a slightly shorter wheelbase (25mm) which I got by moving the K75 engine forward 75mm so's it had the same relationship to the front wheel as the K100, and then adding this 50mm spacer:
It's hard to say whether the gearbox is shorter now as it's gone but the steel frame gearboxes do extend back to carry the swing arm.
I'll be interested to see how it handle when it's finished. The best thing I ever did was pare off as much weight as I could.
I used the Mono rear end on my track bike because it's 40mm-ish shorter and no-one wants the QE2 round Donington Park do they?

K75 Madass Brick10

K75 Madass Img_2110

    

37Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 5:56 pm

chris846

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Hi Mike
I followed your thread about the Braun, I remembered them from back in the day. You did a wonderful job, and you are clearly barking mad. Is it something about South Yorkshire?

I live just past Tankersley Manor if you know it, always pleased to see a new face, especially someone who 'gets' Ks.

    

38Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 6:03 pm

chris846

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Yay!
K75 Madass 01010
K75 Madass 01210

    

39Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 6:13 pm

Motorbike Mike

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@chris846 wrote:Hi Mike
I followed your thread about the Braun, I remembered them from back in the day. You did a wonderful job, and you are clearly barking mad. Is it something about South Yorkshire?

I live just past Tankersley Manor if you know it, always pleased to see a new face, especially someone who 'gets' Ks.
Yes I know Tankersley Manor very well, I used to ride dirt bikes all around that area many years back.
Barking mad? How very dare you sir! I just like to turn up at a track day with something different, I've done the R1 Superstock bit but riding the K is very satisfying-in a barking mad way obviously.
I'll be doing some Classic Bike track days next year, you should come along...with your K75?  Twisted Evil

    

40Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 21, 2017 7:53 pm

92KK 84WW Olaf

92KK 84WW Olaf
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That's what I love about this forum, someone comes in and suddenly its like they have been here for ages. My K1100LT is barking mad too, cracked header and a fine bark.

Looking forward to reading more of these adventures.....

Wondering could we somehow get a K meet up that might coincide with one of these meetings somewhere. Funny think Yorkshire, a lot of our  Ks have been there in parts spirit.

Now for a really stupid question but no so stupid because I recall this sometimes happened with cars and 4 or 5 speed gearboxes. Is it possible to put the inners from a K1200 6 speed gearbox into a K1100 gearbox? Has anyone ever tried it?


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

41Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 22, 2017 7:29 am

Motorbike Mike

Motorbike Mike
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@92KK 84WW Olaf wrote:That's what I love about this forum, someone comes in and suddenly its like they have been here for ages. My K1100LT is barking mad too, cracked header and a fine bark.

Looking forward to reading more of these adventures.....

Wondering could we somehow get a K meet up that might coincide with one of these meetings somewhere. Funny think Yorkshire, a lot of our  Ks have been there in parts spirit.

Now for a really stupid question but no so stupid because I recall this sometimes happened with cars and 4 or 5 speed gearboxes. Is it possible to put the inners from a K1200 6 speed gearbox into a K1100 gearbox? Has anyone ever tried it?
Concerning the meeting, There are a group of guys that have K1's and a few other K's I met at Donington last year who are meeting again in May next year at the Endurance Legends event again at Donington.  It's classic bike meeting with lots to see and they run a classic 4 hour endurance race which I think is something special.  http://www.endurancelegends.co.uk/  

Six speed internals don't fit inside the 5 speed box, they're just too different. I'd have done it long ago if it were possible.

Freddie Spencer was there at Donington...
K75 Madass Img_4011

...and so was I. I had to retire my bike after it destroyed the head gasket so I place it with the other K's.
I'll be there again next year.
K75 Madass Img_4010

Olaf, you already know of Frank Miles and perhaps some of the other members from the K1,K75,K100 and K1100 purists page on Facebook.

    

42Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 22, 2017 7:49 am

Ringfad

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I can see an Eccentric trip to the UK coming up.

Maybe we can get all the Irish K1's to Donington and a few other's as well.


__________________________________________________
K75 Madass Ir-log10

   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 51K Km     ;BMW; K1100RS Red 1993 70k miles  ;BMW; K100 16V Black (ex ElectricMonk)
    

43Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 22, 2017 7:57 am

Motorbike Mike

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Ooh, that sounds like a good idea.
If this is going to happen, a new post should be started as it's going off at a tangent from the original K75 Madass post.
I can't get involved in directly organising this because I'm riding at the event and I help the organisers out so I'll be quite busy but will help out if I can.

    

44Back to top Go down   K75 Madass Empty Re: K75 Madass on Wed Nov 22, 2017 7:46 pm

chris846

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Sounds a good idea, what's the date in May? I'd love to see the Braun K100 in the flesh. 

I need to get this thing finished then..

K75 Madass 21210
K75 Madass 20010
The first picture is the one I couldn't upload on the Introduction section - it shows the bike as it was a month ago. The exhaust is now finished and I'm on with the wiring. The second picture just shows a bit more of the frame detail. The gap between the seat rails holds the electrics and has covers on the top and bottom to match the oval section of the main frame/tank. The picture shows the 4"x"2 (offcut box section - what else!) that makes a duct to run the wiring out and down to the engine - I wanted to keep it looking as uncluttered as possible.
The seat mounting is like a scaffold clamp, it slackens off and swivels/slides up and down the seat rails so's my short-legged pal can cope. I'm not completely sold on the seat, but the forward slope of the rails and lack of tank means that a conventional seat offers no protection against sliding forwards.

Note the super-cheap ebay speedo - I've been hoovering up info from this brilliant forum about getting it to work, thanks fellas! (what capacitor did anyone end up settling on for the tacho signal?)

    

45Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 28, 2017 5:53 pm

chris846

chris846
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More compromises...
K75 Madass 17010
The list of things that had to be shifted/binned goes on..
This time it was the coils that had a battle with the frame for the same bit of space and, guess what, the frame won (again). The original coil bracket was rotated and altered a bit, but it still ended up leaving a bit of a squeeze between the No1 coil connector and the TPS. I might end up ditching the TPS anyway because I adjust my K100 so's it doesn't cut off on the overrun, which I find makes the bike a bit jerky. Don't know how it'll be without the WOT switch, but I have run the K100 with the TPS disconnected and not noticed any real difference (even on the A/F gauge).

The fuel routing ended up a bit daft. The original plan was to put the pump in the frame/tank, just to keep things uncluttered. The yoke 4"x2" section of the yoke was too narrow for this, so there's an external Bosch type pump in the vertical cylinder mounted on the back of the LH yoke. This was the only place where there was room to put it, but the problem then was how to route the fuel to and from it, incorporating a filter and, ideally, a pre-filter too. The tank outlet is the pipe just above the gear pedal and it uses a Mercedes strainer/outlet that screws into a threaded boss in the tank.
From there, the fuel looks like its piped towards the cylinder head, but it actually turns back on itself and runs close to the gearbox and into the bottom of the pump. 
The pump outlets from the top, and a short pipe takes it to a banjo on the top of the left yoke, where it seems to enter the tank again. In fact the banjo attaches to a tube that runs straight through the tank and out of the bottom where a filter (small black cylindrical object) is attached. The pipe from the filter then goes up behind the coils to the fuel rail RH inlet.
It still seems a daft old setup to me, but believe me I spent hours trying to work out a simpler routing. One day I'll look at it and think "s**t, why didn't I...."

    

46Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 28, 2017 6:26 pm

chris846

chris846
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Slight concerns here all of a sudden..

Just checking ebay for spares, and I've come across a new listing for a fairly manky looking bike, the seller describes it as:

"WELCOME TO THE SALE OF MY BMW K75. BOUGHT IT TO RESTORE, BUT NEED THE SPACE, USED TO RUN GREAT, BEEN SAT IN GARAGE, NOW ONLY RUNS ON 3 CYLINDERS AND HAS DEVELOPED AN OIL LEAK AT THE BOTTOM OF THE ENGINE. ITS TATTY, BAD PAINT ETC, DOES NOT SEEM TO BE ALOT OF RUST."


Am I missing something....?

    

47Back to top Go down   K75 Madass Empty Re: K75 Madass on Tue Nov 28, 2017 7:19 pm

Ringfad

Ringfad
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Check again he has updated the listing.


__________________________________________________
K75 Madass Ir-log10

   ;BMW; K100RS Style Black 1987 105K Km     ;BMW; K1 Black 1993 51K Km     ;BMW; K1100RS Red 1993 70k miles  ;BMW; K100 16V Black (ex ElectricMonk)
    

48Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Dec 14, 2017 4:12 pm

chris846

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Well the wiring's been a bit of a challenge...
K75 Madass 004_310
This proves that you cannot just sling any old butchered loom at a complex piece of equipment and hope that it will attach itself at the correct points and function, oh well.

So three weeks later:
K75 Madass 001_210
I ended up making the loom from scratch, but using the wire and the really useful colour coding from the original loom. I tried to simplify it as much as possible, but...let's not go there.

The instruments are this infamous ebay bad boy:
K75 Madass 00610
Which I thought was a bargain at the twenty quid I paid, but they're now being knocked out at £2.99!! 
What on earth is going on in China?

Elsewhere on this forum there's mention of organ theft to get the speedo to work. Luckily I have several crash victims in the deep freeze. Who's the cool guy who '3d printed' an enclosure for the Motometer board that he nicked from the OE cluster? I mean, talk about a dry martini shaken but not stirred, that's pretty cool, but '3d printing' something at the drop of a hat?, I could cry.

I used one of these, because I am NOT COOL. Nobody is THAT COOL!
K75 Madass 017_310

At least mine's see through...and graduated in, erm, millilitres.....
K75 Madass 02210

Next on the 'voyage of the dammed' (aka making a ebay tacho work) was the gearchange indicator. Not a strictly necessary component of any motorcycle, but I suspect that most committed, half-daft, K owners have a bit of a thing for the old digital gear indicator (am I right?). I know I have, when I first sat on my K100 back in 19 eighty-frozen-to-death, and the little old number-in-a-rectangle spoke to me, it was the start of proper love that's never diminished. There, I've said it.

Clever people, who know what they are doing, have developed proper circuits to do this. But I have to make do with pieces of flint. I can understand a relay. And besides, it only takes an array of six or seven hundred of the little buggers to decode the gearbox sender signal into a set of six 'ons or offs'.
K75 Madass 02310

Actually, by the tenth revision (at least), I'd whittled it down to seven, or four double pole relays. And no, I'm not showing anyone a picture of the 'soldering' on the underside. I've got my dignity you know.
Naturally, the circuit was developed using the latest software, and a rubber(eraser):
K75 Madass 02710
Note that anytime I ever go to Germany (should they ever lift the ban), I'll be completely fluent in colours. 
Is it possible to have a conversation, using just colours....?
Ages ago, the Two Ronnies did a similar thing with letters. Ronnie (Corbett) sat down in a cafe and asked the waiter Ronnie (Barker) "F U N E M?" RB replied "S, V F M". RC followed this with "O K, I L F M, F U N E X?" RB: "S, V F X 2". RC: "O K, I L F M N X, F U N E T?". RB: "S, V F T" and on it went, straight faced, pissingly funny. 

Anyway, here's how to lose a week of your life: take one (slightly) defective gearbox sender, one inadequate crimp connection, and a sliver of verobard copper track about one millionth of an inch wide (and invisible to the naked eye). Combine all of these in the same newly-built circuit and...you get the picture.

Onwards and upwards. That was nothing, when it came to getting the tacho to work I ended up buying an oscilloscope...

    

49Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Dec 14, 2017 5:55 pm

92KK 84WW Olaf

92KK 84WW Olaf
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I love this thread, partly because your project didn't involve the sacrifice of a perfectly good K bike. It is so much more, creative. interesting and a joy to follow.

Looking forward to seeing it in the flesh at the K Fest. Looks like it will be in Porn section as a few folk will have the hots for it.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

50Back to top Go down   K75 Madass Empty Re: K75 Madass on Thu Dec 14, 2017 6:01 pm

chris846

chris846
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Hiya Olaf
K-fest - is that the Donington event next May? if so, are people getting the track day tickets?
cheers
chris

    

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