Author Topic: K75S - Cafe Racer project  (Read 11895 times)

Offline Quiltzig

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  • Posts: 98
  • K Guy
K75S - Cafe Racer project
« on: June 21, 2016, 06:53:07 PM »
So after lurking here for a while, and getting great help from stalwarts like RBM, it is now time to share a bit of what I have been doing, and what I have lined up for this winter - it is winter here down in New Zealand btw.

The original bike was a pretty tired looking K75S that had done 117,000kms. When I got it the petrol tank was leaking, the rear pads were down to metal, the fan motor was seized and it had some back yard repair that included a rear brake reservoir from a Holden Barina car, and ordinary rubber lines for the rear brakes, secured with hose clamps. This was just the start!
At this point I have just got to cutting the rear frame hoop off, obtaining parts and fabricating up seat mounts etc.
There is 30 years of accumulated grime and oxidised alloy to clean up, and that is taking a huge amount of time.
Tried Soda blasting, but my home compressor is maxxed out at 60 PSI, so I need about 50% more in order to get that idea to fly.
So far I have used a lot of CAD resources (Cardboard Aided Design) - and have templates made up for mudguards and various mounts, which will get sorted out in the next few weeks when I can scrounge some suitable bits of stainless plate.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline billday

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Re: K75S - Cafe Racer project
« Reply #1 on: June 21, 2016, 11:12:06 PM »
I'm posting this link instead of repeating myself

http://www.motobrick.com/index.php/topic,8176.msg65030.html#msg65030
  • New York State, USA 10977
  • 1985 K100

Offline jjs1234

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Re: K75S - Cafe Racer project
« Reply #2 on: June 22, 2016, 02:41:06 AM »
You linked to my thread?
  • Northern California
  • 1984 K100
Check out my build! Complete tear-down!
Mr. Creative

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #3 on: June 22, 2016, 07:06:54 PM »
You linked to my thread?

If you are referring to the un-supported swingarm??
It was only like that for a day, then it was removed, so no dramas on the boot.

Most of the rubbers are going to be replaced anyway, as they are 30 years old a brittle as hell.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #4 on: June 22, 2016, 08:54:25 PM »
Have now almost finished the tail section. Have fitted a Lithium battery (saving 7Kg in weight) - and it still does 210 CCA and 14aH. I have mounted the ECU under the seat, and cabled a custom cable for the battery up to some terminals mounted into the electrical box. This will allow for easy access to connect a charger. Thanks to RBM I have modded the BMU to accept LED indicator bulbs, which are now mounted in the cut off tubes of the rear hoop tubes. The wire holding up the air filter is temporary - I am still deciding on a bracket.
Here are a few recent pics.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline beemuker

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Re: K75S - Cafe Racer project
« Reply #5 on: June 22, 2016, 11:41:24 PM »
I stopped at where you cut into the frame.
  • Panama City, FL
  • 94 K75s , Dakar yellow ABS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #6 on: June 23, 2016, 12:51:05 AM »
If it is any consolation, I do have another K75S that I am keeping in original condition, and it is mint - perfect & factory in every respect (except for Koni rear shock).
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #7 on: July 10, 2016, 08:34:16 PM »
Progress on the project bike in the last few weeks has been mainly around removing very grubby parts and cleaning, soda blasting, more cleaning, polishing and lots of silver rub and buff.

The fan motor was seized and despite a week of soaking the bearing in various solutions, and copious amounts of WD40, it was unsalvageable, so a new one was obtained from EuroMotoelectrics. It now runs like a charm, so moved on to renovating the starter and alternator. Brushes in both were good, so they just got a clean-up and treatment with Caig copper paste.

Here are some before and after pics of other parts.
Work done so far:
Cut down front fenders to shorter length and pointed style to match rear cowl.
Mounted captive nuts in seat pan to secure it to the main rear fairing section.
removed handlebars and top fork yoke to prepare for when clip on bars arrive.
replaced fan motor, refurbished starter motor and alternator.
Soda blasted rear swing arm, rear hub, starter, alternator & various other parts.
Killed rust on dozens of bolts and brackets, sanded them ready for painting.
Removed instruments and headlight. Cleaned rust from headlight chrome. It came up amazingly well.
Just about to remove clutch and gearbox for degreasing and soda blasting this weekend.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline jc55

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Re: K75S - Cafe Racer project
« Reply #8 on: July 11, 2016, 09:39:49 PM »
Your pics are like, 7GB. I want to be able to see your project(battery mounting, etc), can you shrink them down?
  • Carrollton, Ohio
  • '90 K100LT '77 Gl1000

Offline Quiltzig

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  • K Guy
Re: K75S - Cafe Racer project
« Reply #9 on: July 12, 2016, 12:11:19 AM »
Sure, I can do that.
I forgot that I had my camera set on a fairly high resolution for some other work I was doing.
Will post some smaller sized pics later today.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • K Guy
Re: K75S - Cafe Racer project
« Reply #10 on: July 12, 2016, 12:33:07 AM »
Picture of battery mount in rear cowl section.
What I did was to cut a small square of alloy sheet, fold it up on the sides with a small 5mm lip on the sides, and a bigger 12mm lip at the rear. It was epoxied in place in the rear cowl.
I have a couple of holes in the rear lip through which a single length of bungee cord is threaded. This holds the battery in place nicely.
There are foam pads under the battery and at the rear to cushion it.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • K Guy
Re: K75S - Cafe Racer project
« Reply #11 on: July 12, 2016, 12:37:50 AM »
Pic of the rear cowl with tail lights in place. The indicators are mounted into the ends of the cut off frame tubes. The bulb holders are held in place by folding the bases to create a friction fit and then injecting silicone sealer around them to prevent water ingress. Once the bulbs are installed (they are LED types) I will cover the bulb and the frame tube in clear heatshrink tubing. On the left you can see one of the bulbs held in place with some tape whilst the silicone was curing.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #12 on: July 12, 2016, 12:56:53 AM »
More pics of the parts that were soda blasted and then polished up with silver RubNBuff.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • K Guy
Re: K75S - Cafe Racer project
« Reply #13 on: July 12, 2016, 01:08:17 AM »
Pic of the front mudguards. I tried a dremel with cut of wheel first. It was slow and not very clean. For the second guard I used tin snips which gave a cleaner sharper cut edge and was far faster.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline jc55

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  • Posts: 166
Re: K75S - Cafe Racer project
« Reply #14 on: July 12, 2016, 06:45:06 AM »
Wow, thanks for shrinking them down. Now I can see them :)
Nice work! Those lithium batteries seem to be the real solution. I like the tail lights as well.
  • Carrollton, Ohio
  • '90 K100LT '77 Gl1000

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #15 on: July 13, 2016, 05:50:01 PM »
Thanks for your comments.
Once I get the seat pan back from the upholsterer and the tank and tail from the painter I will post more pics of the way that I am going to try to solve the mish mash of visual lines that are a part of the standard K75 / 100 frame, tank, seat design. I have also formed up a Perspex rear mudguard and will see how that all comes together. The number plate location is exercising my brain at present.... 
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Jeff Sichoe

  • kind of a big deal at the cracker factory
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  • ruddy bastard
Re: K75S - Cafe Racer project
« Reply #16 on: July 18, 2016, 09:02:33 PM »
Damn, making progress in leaps and bounds!

Do you have any idea (sketches etc) of what you want the finished product to look like?
  • Welly, NZ
  • 2 x sad k75s'

Offline Quiltzig

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  • K Guy
Re: K75S - Cafe Racer project
« Reply #17 on: July 18, 2016, 09:28:38 PM »
Damn, making progress in leaps and bounds!

Do you have any idea (sketches etc) of what you want the finished product to look like?

Yeah - I have an idea, but it is all in my head and I can't figure out how to download it out of there into the PC !

I have a whole heap of stuff on order, so within the next few weeks it will start to take shape. I just got the seat foamed, so have to get the final shape for that sorted.
The rear cowl is at the painters. The clip on bard will go on this weekend, then I will design the speedo mounting plate. It is all being done by eye and gut feel at the mo.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #18 on: July 18, 2016, 09:59:41 PM »
So I finally got the upper triple T off the bike - it has seized on there with a lot of corrosion and only took a week to loosen up with WD40 and a final bit of persuasion with the rubber mallet !

The attached pic shows the results of a clean up with baking soda and white vinegar, which took off the 30 years of accumulated grime really well.
Half the picture is as it came out after the baking soda clean. The other half is how it comes up after using some RubNBuff on it. Tonight it will get a final buff and be ready to go back on after the clip on bars have been fitted.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #19 on: July 22, 2016, 08:16:02 PM »
The painter says I will have my mudguards, tank and seat / tail section back next week.
So I set about getting the seat pan foamed. Now I have to take the seat off my wifes bike so I can sit the seat pan on that bike and see where I need to shave the foam to get the shape and feel that I am after. That's the next job in the line. First I had to hone out the strap-ons bars that were 41mm ex China.. the K75 is 41.5mm, so I used a round file to start with and followed up with some sandpaper taped around a hole saw & trusty battery drill.
My workshop is not that well equipped, so I make do with what I have. It only took an hour and a half of filing and sanding and now the bars are on!
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline pablooo

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Re: K75S - Cafe Racer project
« Reply #20 on: July 23, 2016, 05:03:52 PM »
I'm guessing you'll be doing the same for the actual bars? As they're probably 7/8" instead of the exact 22mm sizeof the controls.
  • Austin, Tx
  • BMW K100, FZ-07

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #21 on: July 24, 2016, 04:45:51 AM »
No - the bars were 22mm and the controls only needed a light buff, a little lube and they slipped straight on very easily.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #22 on: July 26, 2016, 04:51:28 PM »
The bars are now fitted. Just have to wait till my tank comes back from the painters before I will know if they foul it or not.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS

Offline jc55

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  • Posts: 166
Re: K75S - Cafe Racer project
« Reply #23 on: July 26, 2016, 09:58:54 PM »
I love the look, any idea on gauges yet? (Sorry if you mentioned it previously)
  • Carrollton, Ohio
  • '90 K100LT '77 Gl1000

Offline Quiltzig

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  • Posts: 98
  • K Guy
Re: K75S - Cafe Racer project
« Reply #24 on: July 27, 2016, 07:15:41 PM »
I have a combined tacho and digital speedo from E-Bay (a Chinese 12,000 rpm type) that I am going to use.
At present I am doing the CAD (Cardboard Aided Design) - of the alloy plate that will fix to the old handlebar mounts.
It should look quite cool, probably use 5 or 6mm alloy plate & get it water jetted out.
Will post some pics of the template etc when I get things finalised.
  • Hamilton - New Zealand
  • K75S
1987 K75S - cafe racer project
2016 R9T (wifes ride)
2004 K1200RS