BMW K75 Cafe Racer – Post 1

The latest build to come into the JAX Garage workshop is a 1986 BMW K75. It was purchased as a wreck, with the front forks damaged, headlight smashed and a dent in the right side of the fuel tank. Based on that it’s likely that we’ll be experimenting with a front fork change. The bike runs well and has approximately 130,000kms on the clock. With no damage to the engine, oil that looks in good condition and all electronics operational, this should be an exciting build. It’s also the first build that Dom and I will be doing together. Dom has over 30 years’ experience as a motor mechanic, but is really an all-rounder when it comes to anything mechanical. I think I’ll enjoy getting my hands dirty and learning a thing or two at the least.

BMW K75 Cafe Racer Build 1

BMW K75 Cafe Racer – Post 2

Now that the bike is on the bench the tear-down and fun can begin! It’s also a time to start thinking about how to go ahead with this build. Currently, there isn’t really a plan and we’ll be taking it week by week, but the first thought is that the frame, engine and transmission need a paintjob (Satin black drive train and gloss black frame for contrast). It’s also likely that we’ll turn this into a café racer, despite the awkward 1980’s lines that make the flying bricks tricky to work with in terms of styling.

BMW K75 Cafe Racer Build 2

BMW K75 Cafe Racer – Post 3

We purchased a wrecked 2001 CBR 929 RR Fireblade at the same time as the BMW. This was purely done because this will act as a donor bike for the BMW. That is, the upside down front forks will be used to make for a more aggressive and modern front-end. The triple tree will need to be worked out. The rear sets will also be used and adjusted to suit the build. We’ll see if we can use anything else here. The rest will be sold as parts on EBay to recoup some of the costs.

BMW K75 Cafe Racer Build 3

BMW K75 Cafe Racer – Post 4

Progress report: The bike is not as dirty as I thought it would be and it looks like it’s had a very good life. There are no leaks or any excessive build-up of grime and dirt. Cleaning it up and getting it prepped for painting shouldn’t be too arduous.

BMW K75 Cafe Racer – Post 5

BMW K75 Cafe Racer Build 4

Got the original BMW K75 head stem modified and pressed-into the Honda CBR bottom triple clamp. The top triple will also be used in the build. This took some thinking and a lot of work to achieve. Thankfully I have Dom working on the bike with me. He ended up extending the original head stem and milling away the bottom and front of the CBR top triple to clean things and allow it to sit in place correctly.

I’ve designed and manufactured a head stem and triple clamp kit for future BMW K Series projects to avoid this kind of work again. If you’re thinking of doing the same kind of front-end conversion then follow this link: https://www.jaxgarage.com.au/shop/ .

BMW K75 Cafe Racer – Post 6

And here is what the front end will now look like with the CBR upside-down forks. Note that the original lateral offset from the head stem changed from 56mm to 30mm. the forks are also larger in diameter. The lock-to-lock steering angle is therefore changed from original to avoid striking the tank. It should now manoeuvre like a modern day sports bike, which can be a pain pushing it around or at extremely low speeds.

BMW K75 Cafe Racer Build 5

BMW K75 Cafe Racer – Post 7

BMW K75 Cafe Racer Build 6

Managed to get it all clean and prepped up for Dom to paint. Came in after work to see it with a fresh coat of paint. The engine and transmission was all painted a satin black. A black crinkle finish was applied to the crankcase and camshaft covers. A marked improvement!

BMW K75 Cafe Racer – Post 8

Now that the engine has been painted, it’s on to the wiring. The idea is to remove the electronics box underneath the seat and hide all the electronic in a seat cowl at the rear of the bike. This should leave an empty cavity underneath the seating area of the bike. Because this bike has an 80’s EFI engine, it has a tone of wiring and components. Everything talks to each other. That is, the ICU, airflow meter, EFI computer and the instrument panel all communicate to let the bike start and continue to run… So I’ll be removing what I can but will be keeping most of it. We’re not going with the option of using a Motogadget M-unit on this build either so it’ll be quite the challenge.

BMW K75 Cafe Racer Build 7

BMW K75 Cafe Racer – Post 9

BMW K75 Cafe Racer Build 8

I’m still working on relocating the wiring. Dom has in the mean-time gone ahead and given the wheels a fresh paintjob. We’re going for a gloss black finish here to match the frame, and which should give a good contrast to the satin finish of the drive-train.

BMW K75 Cafe Racer – Post 10

All done with relocating the wiring, but still a long way from finishing the entire loom, let alone integrating the CBR switches and the aftermarket speedo. For now though, the rear sub-frame has been cut as this will be a single seater café racer bike. No need for the extra weight and it’ll tidy up the back. All unnecessary tabs were also cut away to clean up the frame.

BMW K75 Cafe Racer – Post 11

BMW K75 Cafe Racer Build 9

It’s starting to look like a bike again. The fibre glass seat came in today and we decided to fit that on along with the rear wheel and tank just to see how it all fits up. Extremely happy with how it’s shaping up so far. There will need to be some modification with the fibreglass seat in order fit in the electronics and allow them to be accessed. The Shinko 230 Tour Master tyres are looking the part too. Also a new push-rod actuator was fabricated to engage the rear drum brake (to suit the CBR 929 rear sets).

BMW K75 Cafe Racer – Post 12

Got a chance to get back in the workshop and jump aboard the bike in order to test the position of the rear sets. I’m 178cm tall (5ft10) and it feels great so far despite no comfortable seat underneath. The gear change lever can be adjusted so as this thing gets on the road it’ll be set up to feel just right. Now we’re using the 929 RR rear sets and we needed to fabricate adapters to make them suit the bike. This was simple enough we utilised the same mounting holes as the original rear sets. The original gear lever had to be cut, drilled and tapped to allow for a rod to be attached that would seat in the 929 ball joint.

BMW K75 Cafe Racer Build 10

BMW K75 Cafe Racer – Post 13

Set-up all the levers and switches on newly purchased clip-on handle bars. We’re once again using items from the 929 RR. That is the switches, brake levers and reservoir are those used for the 929 RR. The original switches weren’t in great condition and were dated. To upgrade the look and feel of the bike we decided to use the more modern components. The CBR front-end is really taking shape now.

BMW K75 Cafe Racer Build 11

BMW K75 Cafe Racer – Post 14

Finally managed to do the first pass test on the wiring. At this stage, all that was done was relocating the wiring and componentry to the rear of the bike. All lights (indicators, position, brake, headlamp etc. were all operational). The headlamp we decided to use was a locally purchased STEDI Carbon Black 7 inch headlamp. These can be used on motorcycles and are compliant with Australian Design Standards and UN Requirements. The problem with the headlamp was mounting, as there was no convenient way of doing this we had to fabricate a steel ring, drill and tap the back of the headlamp housing to attach it. Came up really neat in the end.

At this stage, the speedo is operational… well almost. The neutral light isn’t working and we have no gears. I’m not too fussed about the gears not showing but the Neutral light is definitely a must in my opinion. After doing some research the old instrument cluster (commonly referred to as a breadbox) had all the circuitry involved in showing the neutral, sending this message to the across to the various components and allowing the bike to start. The quick solution here is purchase a breadbox adapter that is readily available on the market. We’ve opted for the Alex Joost breadbox adapter in this case. Now to wait for it in the mail.

BMW K75 Cafe Racer Build 12

BMW K75 Cafe Racer – Post 15

BMW K75 Cafe Racer Build 13

It’s taking really nice shape now. Still a lot of work to do but it’s coming up great so far. The Shinko boots look fantastic with the high walls and the CBR front-end really gives the bike an aggressive stance. We’re also experimenting with how a Toce 3-end exhaust pipe would look. Maybe a bit too much like a sports bike but it’s growing on me.

BMW K75 Cafe Racer – Post 16

BMW K75 Cafe Racer Build 14

The tank had a dent in the right hand side when we purchased it. We decided to knock out the badge inserts of the tank as well and fill in where required. The tank should now come up nice and clean when it’s finally painted. Only to choose a colour in the coming weeks.

BMW K75 Cafe Racer – Post 17

BMW K75 Cafe Racer Build 15

Today’s bit of work involved cutting out numerous pie cuts and directing the exhaust out toward the right hand side of the bike. At some stage I’ll do a quick guide on how to do pie-cuts. The pie cuts will connect to a muffler on the right side. Still considering whether the outlet will involve the Toce component or something custom. So far we have 31 separate pie cuts that will need to be welded. I anticipate close to 50 individual cuts before it’s all done.

BMW K75 Cafe Racer – Post 18

BMW K75 Cafe Racer Build 16

Tank on and patched up. I’m experimenting with the foam seat and have mocked up a shape that suits the flow of the tank and the rear cowl. The seat is too soft though I’ve just used some soft open cell foam that has been laying around. We really need high density open cell foam for this application. It’s easy to glue on, shape and is dense enough to not completely collapse under weight. Once I’m finally happy with the seat I’ll be taking it to a local upholsterer to get it done. Most likely black leather seat. Upholstery is not a skill that we have mastered just yet so it’s best to take it to the professionals.

BMW K75 Cafe Racer – Post 19

BMW K75 Cafe Racer Build 17

A quick update on the exhaust piping. The pie cuts are all tacked up so far. Thanks Dom! Dom will be doing all the welding on the bike. Unfortunately at this stage my welding isn’t up to scratch so I’ll be doing the measurements, cuts and plotting it all out. But the final finishes on the bike need to be perfect. Luckily Dom has a wealth of knowledge and experience in all sorts of welding.

BMW K75 Cafe Racer – Post 20

BMW K75 Cafe Racer Build 18

The frame was cleaned and all the unnecessary tabs removed to provide a smooth finish. After a few layers of undercoat and a few more of two pack black gloss paint, the finish is ultra-smooth.

BMW K75 Cafe Racer – Post 21

Started prototyping the custom triple tree for future builds on the 3D printer. It’ll be a plug and play installation for CBR 929/954/1000 RR forks used on K Series bikes. Say goodbye to chopping and changing the existing CBR triple tree and the K series headstem etc. I’ll be testing it shortly and if all clears, be cnc machining it out of 7075 T6 Aluminium (Race grade quality).

BMW K75 Cafe Racer Build 19

BMW K75 Cafe Racer – Post 22

Painted frame, wheels, and callipers all on! Now to get onto the tank and seat. You may have also noticed that the original air box and filter were removed. The air-flow sensor has been relocated in a much simpler set-up. We’ll be designing a custom intake manifold here that hugs the side of the bike.

BMW K75 Cafe Racer – Post 23

BMW K75 Cafe Racer Build 20

Acewell Speedo on! Made a bracket that comes in from the back. Dom machined out an aluminium cover for that ugly headstem nut on the lathe. Came out nice all polished up. Now to add power to the speedo and get it fired up.

BMW K75 Cafe Racer – Post 24

Extremely happy with how these turned out. Custom Triple clamp plug-and-play installation to suit K Series bikes with CBR 929/954/1000 RR forks. CNC machined from billet 7075 T6 Aluminium providing extra stiffness where it’s needed. It may be something of an overkill for café racer / custom bikes as they only use 7 Series triples for racing applications but I thought I’d step up with the quality. Say goodbye to chopping and changing the existing CBR triple tree and the K series head stem etc.

BMW K75 Cafe Racer Build 21

BMW K75 Cafe Racer – Post 25

BMW K75 Cafe Racer Build 22

Tank and seat/cowl prepped for painting. Now to let the undercoat dry. Still deciding between Nardo Grey, Estoril Blue or Urban Green. It’ll likely be one of these colours, but I’ll have to put swatches or something similar up to the bike to decide. I got some great feedback from several Instagram followers about all three colours. I think either colour will be great.

BMW K75 Cafe Racer – Post 26

BMW K75 Cafe Racer Build 23

BMW K75 Cafe Racer Build 24

I couldn’t help myself and wanted to try the tank and seat on the bike before Dom starts painting. I think it’s coming up nicely already. Also, I’ll be using the rear cowl cavity as an electrical compartment, so I should have a nice clean space underneath seat. At the same time we’re making front and rear fenders to suit. The chain that can be seen on the rear tyre provides a general guide on far away the guard has to be from the tyre. For the rear though. This will need to be considerably greater as the guard comes off the rear transmission housing and the swingarm moves separately.

And just a great shot of the bike – Excuse the messy workbench. Work in progress here!

BMW K75 Cafe Racer Build 25

BMW K75 Cafe Racer – Post 27

BMW K75 Cafe Racer Build 26

Aerial shot of the builds in the workshop (Not including the CB750 build). The K75 is seeing all the attention and love so far. The Yamaha XS400 hasn’t seen much love lately but I’ll be doing a build series just like this for all builds/ share all the info over Instagram.

BMW K75 Cafe Racer – Post 28

BMW K75 Cafe Racer Build 27

Tank and seat cowl all painted. In the end I decided to go with Estoril Blue. Thank you to followers on Instagram @anglemang @baycityrestorations @theflyingbrick_au @alfredthemini @heinrich_the_k1100 @20mmrider and many more for your input. It was a difficult choosing between the blue, grey and the green but got there in the end.

BMW K75 Cafe Racer Build 28

Here’s a close-up of the K75 tank. The BMW Estoril Blue came out fantastic. A big thanks to the in-house painter Dom! Always a first-class job.

BMW K75 Cafe Racer – Post 29

BMW K75 Cafe Racer Build 29

Now that the tank and seat have been painted it’s time to shape the seat. Here we’re using high density foam that was stuck on by a local upholster. To get the right line and shape we need to shave it to the right moulds and contours of the seat cowl and the tank. Another important to decision to make as well: What colour leather and stitching to pick?

BMW K75 Cafe Racer – Post 30

In case you’re wondering what the bike looks like so far here is. The seat has been sent back to the upholster to work his magic. There’s still a bit of work to do here such as:

  1. Sorting out all final electrical.
  2. Creating the custom intake – this will be a nice surprise I think.
  3. Creating the custom exhaust muffler – decided not to go with the Toce outlets.
  4. Some final touches here and there.

BMW K75 Cafe Racer Build 30

BMW K75 Cafe Racer – Post 31

Here are a few shots of the bike that were taken as a mock-photoshoot. Did this just for fun as we wait for the bike seat to come back. Not far from completing this build now. Only a bit of fabrication work and painting and it should be done.

BMW K75 Cafe Racer Build 31

BMW K75 Cafe Racer – Post 32

The pie cut exhaust has been completed and will be built in two stages. Pie cut exhaust will wrap around from left to right where a stainless steel muffler can be riveted in place. This will allow us to fill the muffler with sound deadening.

BMW K75 Cafe Racer Build 32

BMW K75 Cafe Racer – Post 33

The seat has come back and here it is. Extremely happy with how it’s turned out. We considered tackling the upholstery ourselves but ultimately decided against it because we wanted this to be perfect. Glad we went down this route as it’s come up great and well worth getting an expert to do it. You’ll also notice we went with blue stitching. It matches the Estoril Blue really well.

BMW K75 Cafe Racer Build 33

BMW K75 Cafe Racer – Post 34

Because we removed the big air box originally located underneath the tank we decided to make a custom pie-cut intake to match the exhaust. The pie-cuts connect to a diagonal intake manifold that houses a removal filter. Did I mention it was all stainless as well? Dom did a great job welding all this up and it should be a stand-out feature on the bike.

BMW K75 Cafe Racer Build 34

BMW K75 Cafe Racer – Post 35

BMW K75 Cafe Racer Build 35

Front and rear fenders all done and painted a nice satin black. Nut-rivets were added making for an easy installation. Dom shaped and welded the bars that hold the fender up. The rear fender will need to be adjusted once we get some weight on the bike because it’s fixed compared to the swing-arm.

BMW K75 Cafe Racer – Post 36

BMW K75 Cafe Racer Build 36

A bit more fabrication. This overflow canister will now live underneath the tank where the air box was originally located. It’s got the same volume as the original and we’ll have a breather outlet on the top left. Here’s also a shot of Dom welding it all up.

BMW K75 Cafe Racer – Post 37

A few touch ups on the remaining bit of wiring. Here I’m using an Alex Joost Breadbox Adapter to get the speedo Neutral light working. It also allows the charging system to work, although I had to solder in a 120ohm 5 Watt resistor to allow the charging system to come in on at idle. The rest of the components were placed in the rear cowl and now that it’s all secured in place it’s time to put everything back together and actually have a finished BMW. It’s been a bit of a journey but a great one.

BMW K75 Cafe Racer Build 37

BMW K75 Cafe Racer – Post 38

Photoshoot day… I thought I’d kick it off with a selfie despite having a bad hair day! Pretty exciting day as the bike is all done and dusted. We’ll be heading nearby to an engineering factory (they weld up last silos, pressure tanks and other equipment) for the photoshoot. It had large open spaces and great lighting.

BMW K75 Cafe Racer Build 38

BMW K75 Cafe Racer – Post 39

So Yesterday we did the photoshoot. I think it was a success but the photos need to be selected and some post editing needs to be done. Here are the behind the scenes shots.

BMW K75 Cafe Racer Build 39

BMW K75 Cafe Racer Build 40

BMW K75 Cafe Racer Build 41

BMW K75 Cafe Racer – Post 40

Here are my Top 3 shots of the photoshoot all edited and complete.

BMW K75 Cafe Racer Build 42

BMW K75 Cafe Racer Build 43

BMW K75 Cafe Racer Build 44

BMW K75 Cafe Racer – Post 41

Got some great news today. The build was accepted by one of the largest online publications for custom builds. Pipeburn.com decided to do a feature article on the bike. Here is the link for anyone interested in reading it: https://www.pipeburn.com/home/2019/10/30/kreative-expression-bmw-k75c-by-jax-garage.html

BMW K75 Cafe Racer Build 45

BMW K75 Cafe Racer – Post 42

The bike has had a great reception online via the likes of Pipeburn.com and Instagram. Here are some highlights from BMW Motorrad Australia to Café racers of Instagram. Couldn’t be happier.

BMW K75 Cafe Racer Build 46

BMW K75 Cafe Racer – Post 43

Whilst the bike is up for sale we haven’t officially started advertising it yet. Don’t expect to see the last of the BMW K75C Cafe Racer. It has had a tremendous reception online and locally so I’ll be updating this blog with any more features/sales/progressions. But it’s likely you’ll hear the news first on Insta so if you’re not following just yet make sure you do @jaxgarageau

 

BMW K75 Cafe Racer – Post 44

This has been absolutely great week. Most of it was spent with family and friends due to Christmas, but we still had time to get in the workshop and play with the bikes. More importantly however, is our latest K75C feature. The bike has had a great reception since debuting on Pipeburn.com and has since been featured in Australia’s leading motorcycle travel magazine; Australian Motorcyclist Magazine (January Issue 83). We received 4 pages on the build and couldn’t be happier. If you’re up for it you can go to their website and download an online copy or get an issue mailed out to you: http://ausmotorcyclist.com.au/ The magazine also has two other great builds in it, an Indian and a Ducati. Check it out.

BMW K75 Cafe Racer – Post 45

So it’s been 3 months (mid Feb 2020) now since the bike was originally completed and we got the chance to do some last minute ride photography and filming. I’ll make sure to keep you all posted when the videos go up live, Here is a sneak peak photo of the filming.

BMW K75 Cafe Racer Build 47

 

BMW K75 Cafe Racer – Post 46

The filming shown above in post 45 was prompted by a recent discussion with the creator of Racer TV on Youtube. After weeks of back and forth and going through every detail of the build the video finally went live on Youtube late last week. I had to refrain from from sharing it with you all because it may influence in the Youtube algorithm. Let’s just say I was absolutely itching to let everyone know about it. The video covers the BMW K75 Cafe Racer build and a bit about us and what we do so check it out [here]. Finally, to the creator of Racer TV, VItor, Thank you for doing such an amazing job, and we’re absolutely thrilled and honoured that you made a video on the K75. For the rest, ENJOY.

BMW K75 Cafe Racer Build 48

 

BMW K75 Cafe Racer – Post 47

This is officially the last k75 post. The k75 has officially been picked up by the new owner. It’s time for him to Enjoy it. It’s been an absolutely fantastic project, and if you’ve been following, I hope you enjoyed the weekly updates. For now, there’s more on in the Garage so check out the other builds.
BMW K75 Cafe Racer Build 49

 

RESOURCES:

Wiring Diagrams

Trouble-shooting

How To’s

Repair Manual