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Old 3rd May 2021, 07:33   #1
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Default Restoring my 1974 BMW R90S 900cc Motorcycle

I bought the bike in 1984 at the height of the financial crisis. The guy was desperate to get rid of it. I offered him 1400 euros but he wanted 3000. I started to drive away and he bicycled after me and begged me to take the bike. Those days they threw cars and motorcycles at you and the market was flooded. The bike became mine for 1400 euros.

This is the first run.


The bike was run down but started easily and sounded nice. He told me that he had repaired the gearbox. He did not know what bike he was selling. This is the mother of all superbikes and the first production bike that passed the 200 km/hour mark.
German Hans Muth sketched this bike on a piece of paper in a hotel room in Amsterdam. The same guy designed the Suzuki Katana.

The bike certainly reised eyebrows when it was released. From being an "old mans" bike, here was a potent tourer with twin Dellorto carburettors. These Dellortos have an acceleration pump built in. When you open up, about 2 ml of fuel is sprayed directly into the cylinder head. Many of these bikes were used for racing.

https://www.motorcyclistonline.com/1...side-down-bmw/

After a few days of riding I heard a worrying clicking noise from the gearbox and I parked it and it stayed that way for 19 years. I was going through a divorce and hid the bike in a backyard shed. I paid for the bike and did not fancy her getting half of it. In those years the previous owner tried several time to buy it back, offering me twice the price but I declined.

I 2004 I decided to put the bike back on the road and started the stripdown in my living room and later moved it to a motorcycle club. The bike was sandblasted primed and resprayed in the original Silver Smoke.

All the work other than the sandblasting and conversion of the cylinder heads for lead free fuel were done in house by me.
I made up a paint room with an old kitchen ventilator and started by trial and error. I painted the tank 4 times.

There is no chain on the bike and it is shaft driven. I replaced the bearing and seal and adjusted with shims. This is a first generation drive with no damping on the driveshaft.

The bike had contact breaker ignition. This was replaced with a Silent Hektik digital ignition. This was made for the VW engines used in small planes. The 260W alternator was replaced with a 400W stator and windings hand made by Jeff Lee in Taiwan.
The total cost of the project is difficult to say but when I started, I had about 6000 euros. Some of this money went on a trip to Germany and telephone calls and shipping. Parts came from several sources from Germany, UK, Switzerland, the US and Taiwan.

On my forst trip to Germany with the bike, the club there figured that I could ask for about 15,000 euros. This because it is the first generation R90S with a very low frame number of 350. The engine has the same number. The bike was produced in October 1973. All castings have this date.



These are the tools I started with. Bought over a period of 30 years.
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Bike in the living room. The engine and gearbox are out. The rest of the bike was dismantled here and sent off for sandblasting. It was easier to start work as soon as i returned from work.
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The instruments were all rotten. There were many people following me online and a German dealer contacted me and said I was welcome to drop by and check out his stock of old parts. I bought a new speedometer and rev counter from them. They even got me the original enameled BMW badges as the old ones were damaged by airgun pellets.
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All ready for sandblasting but he was drunk and sprayed res Rustoleum and messed it all up. I had told him that I wanted them in bare metal but he tried to hide his shoddy work with paint. I refused to pay him and finally I agreed to give a 6-pack of beer for his troubles. I later found out that he is hooked on alcohol and drinks on the job.
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I was boiling when I saw this. It was holiday season and all shops were closing. A guy who makes grave stones was kind enough to agree to do it for me. Otherwise It would have delayed me for 2 months or 3.
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The black parts are sprayed jet black. They were primed with a 2-component etching primer. All paints used were from Standox
Restoring my 1974 BMW R90S 900cc Motorcycle-paintedframe.jpg

For the pinstriping I sprayed on a base gold colour and taped it with 3 mm masking tape. After the base colour was laid on I removed the masking tape before the clear coat.
Restoring my 1974 BMW R90S 900cc Motorcycle-tankbasegold.jpg

The tank was the first part that was ready. I practiced my spraying skills on the tank. This was my fourth attempt. I laid on 6 coats of clearcoat. It was then wet sanded with a 2000 grade paper to remove the mosquitoes and then polished with 0000 grade steel wool before being cut and polished
Restoring my 1974 BMW R90S 900cc Motorcycle-gastank.jpg

The heads were converted for lead free fuel and both valves replaced with exhaust valves replaced with the sodium filled Swiss Intervalve.
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Here the cylinders are painted and the steel pushrod tubes replaced with stainless steel tubes.
Restoring my 1974 BMW R90S 900cc Motorcycle-cylinders.jpg

The bike has a dry clutch and appears similar in size to the VW Beetle clutch plate.
Restoring my 1974 BMW R90S 900cc Motorcycle-clutch.jpg

This is how the previous owner repaired the gearbox. He just put in some sawdust to get rid of the noise. He had prepared the bike for sale that way. The box was full of a thick grey porridge. I called the previous owner and he denied it. I asked him to come over to see the birch leaf I found inside and he went silent. He had just opened the cover and added sawdust. This is a common scam to quieten gearboxes and final drives.
Restoring my 1974 BMW R90S 900cc Motorcycle-sawdust.jpg

Here I have emptied the gearbox into a sink for some cleaning. The plastic selector wheel was replace with a ball bearing and all bearings replaced. The input shaft spring was broken and a toothed gear had radial cracks on it.. I bought a used gearbox for parts and all bearings were replaced.
Restoring my 1974 BMW R90S 900cc Motorcycle-insidesgearbox.jpg

I took the cover from a gearbox and machined it to make a tool to shim up the bearings. I made this at a trade school. I know the teacher and he lets me use what I want there.
Restoring my 1974 BMW R90S 900cc Motorcycle-shimmingtool.jpg

These are the tools I made to extract the output shaft from the gearbox. One to hold the shaft and the other to loosen and tighten the bolt.
Restoring my 1974 BMW R90S 900cc Motorcycle-gearboxtool.jpg

I made this tool in ABS first to get familiar with the lathe to practice for the gearbox tool. This tool is used to press in a big oil seal on the clutch side of the engine.
Restoring my 1974 BMW R90S 900cc Motorcycle-oilsealtool.jpg

The steel spokes were replaced with stainless steel spokes I got from Switzerland. Here I am putting on the final touches to make the wheel straight.
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The bike is almost ready. Just needed to get my clock and ampere meter ready. Already registered.
Restoring my 1974 BMW R90S 900cc Motorcycle-bike.jpg
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Old 3rd May 2021, 08:13   #2
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Congrats Indian_2003! That's a lovely bike out there. Very recently a mint R100S showed up in India Link. (The Classic Smoke Red 1978 BMW R100S). I had the opportunity to see this bike closely and was mighty impressed with the way it had been put together. Needless to say that the bike is up for grabs at a price no one can afford it for

Congrats on your R90s.
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Old 3rd May 2021, 16:50   #3
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

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Originally Posted by moralfibre View Post
Congrats Indian_2003! That's a lovely bike out there. Very recently a mint R100S showed up in India Link. (The Classic Smoke Red 1978 BMW R100S). I had the opportunity to see this bike closely and was mighty impressed with the way it had been put together. Needless to say that the bike is up for grabs at a price no one can afford it for

Congrats on your R90s.
The R100S is almost a copy of the R90S but in red smoke. This bike has the standard Bing carburettors. The R90S is faster.
There is a R90S in Hyderabad and owned by a guy called Raj. We are in the same R90S forum in the US. He invited me over to India for some biriyani.
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Old 4th May 2021, 11:51   #4
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

You have a glorious piece of history in terms of motorcycles in your garage. And what a story to acquire it.

These are pure, unadulterated motorcycles with the purest feel, hope I get to ride one someday. If possible, please post up a small video of the twin boxer's exhaust note.

Please keep updating this thread with details .
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Old 4th May 2021, 12:27   #5
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Great job! Very impressed with your paint skills. It is one of the areas of car/bike repair I donít venture into. I just donít have the skills. My wife wonít even let me paint our garden shed, as she tells me I am terrible at painting.

Jeroen
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Old 4th May 2021, 15:36   #6
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Quote:
Originally Posted by Indian2003 View Post
All the work other than the sandblasting and conversion of the cylinder heads for lead free fuel were done in house by me.
I made up a paint room with an old kitchen ventilator and started by trial and error. I painted the tank 4 times.


The steel spokes were replaced with stainless steel spokes I got from Switzerland. Here I am putting on the final touches to make the wheel straight.

The bike is almost ready. Just needed to get my clock and ampere meter ready. Already registered.
That's great skill you have to pull this off in house!

Straightening a spoke wheel is a difficult skill set which even some BMW service centers lack!

The bike deserves more pictures, please share, specially the instruments panel parts

Great job,
surjaonwheelz
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Old 4th May 2021, 16:04   #7
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Quote:
Originally Posted by Sheel View Post
You have a glorious piece of history in terms of motorcycles in your garage. And what a story to acquire it.

These are pure, unadulterated motorcycles with the purest feel, hope I get to ride one someday. If possible, please post up a small video of the twin boxer's exhaust note.
This was taken after a 1200 km trip to the north of Sweden.




Quote:
Originally Posted by Jeroen View Post
Great job! Very impressed with your paint skills. It is one of the areas of car/bike repair I don’t venture into. I just don’t have the skills. My wife won’t even let me paint our garden shed, as she tells me I am terrible at painting.

Jeroen
I did have some painting skills as a kid. I resprayed my own bicycle when I was 11. I used a tin Shelltox hand spray. Some of you might remember the Shelltox DDT that was used against insects.

Outlawed in the West about 5 decades ago due to health risks, these are still being sold in Africa and Asia. Dangerous for Western lives but not so for African and Asian lives. Money rules.

We had green paint at home but I wanted a metallic colour so I filed an aluminium bar and mixed it into the paint and voila! I had green metalic paint.


Quote:
Originally Posted by surjaonwheelz View Post

Straightening a spoke wheel is a difficult skill set which even some BMW service centers lack!

The bike deserves more pictures, please share, specially the instruments panel parts

Great job,
surjaonwheelz
Thanks. This was my first attempt at wheel building, though I have straightened my bicycle wheels myself earlier.

I placed the hub on the kitchen table and and the wheel perfectly centered to the millimeter and cafefully laced them. Once done it was fit to the bike frame to adjust the offset.

Then it was off to the jig for fine tuning. The rims were straightened to about 1.0 mm. BMW accepts 5 mm throw in spoked wheels. After riding for a few days I adjusted the spokes again.

I used to walk around with my tool during motorcycle meets straightening wheels for others.

I will post more pictures. When making the post I had some trouble and the pictures converted to attachments and would not show. I tried to post the maximum 30 but somehow it did not work.

Last edited by Indian2003 : 4th May 2021 at 16:11.
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Old 4th May 2021, 16:37   #8
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

BMW boxers are some of the most amazing machines. I've lusted for then for so long! The first time I saw a classic BMW was 2004 in a vintage rally. It was an R100RS which is well known in the biking circle.

I thoroughly enjoyed going thru your restoration effort and the bike has turned out to be absolutely gorgeous. The smoked effect looks period correct and the engine and peripherals are in place and nothing sticks out. The bike must be a pleasure to ride! I wish you many happy miles with this gem.

Sharing some pics from 2004.

Restoring my 1974 BMW R90S 900cc Motorcycle-dsc01439.jpg

Restoring my 1974 BMW R90S 900cc Motorcycle-dsc01440.jpg

Restoring my 1974 BMW R90S 900cc Motorcycle-dsc01441.jpg

Restoring my 1974 BMW R90S 900cc Motorcycle-dsc01442.jpg

Restoring my 1974 BMW R90S 900cc Motorcycle-dsc01445.jpg
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Old 5th May 2021, 09:22   #9
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Indian2003, we usually hear of barn finds and subsequent restorations, but this is an unusual case of getting the bike out of your own shed after 19 years and bringing it back to its former glory! Your bike looks immaculate. That finish on the paint job is something else! Can you post a closer picture of the tail piece?
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Old 5th May 2021, 10:04   #10
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

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The mufflers look exactly like the RE Interceptor's
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Old 5th May 2021, 10:15   #11
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The mufflers look exactly like the RE Interceptor's
True!
I suppose many twin cylinder bikes will have similar 2 cone upswept exhausts.
The Bonneville that i had also was similar. I recollect the Norton commando had it too. I'm sure there were more.
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Old 5th May 2021, 10:24   #12
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Extraordinary work! But very few pictures to see it's glory is frustrating! Please add more pictures.
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Old 5th May 2021, 10:50   #13
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

Only word that comes to my mind is 'Amazing' both the bike and your short and crisp write up.You are one privileged owner.
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Old 5th May 2021, 13:25   #14
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

One word, Wow. Couldn't think of anything better.

Hats-off to your dedication and I'm speechless with the pin-strip which most renowned painters today couldn't achieve this perfection.
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Old 5th May 2021, 15:35   #15
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Default Re: Restoring my 1974 BMW R90S 900cc Motorcycle

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Originally Posted by neil.jericho View Post
Indian2003, we usually hear of barn finds and subsequent restorations, but this is an unusual case of getting the bike out of your own shed after 19 years and bringing it back to its former glory! Your bike looks immaculate. That finish on the paint job is something else! Can you post a closer picture of the tail piece?
Here are 2 pictures of the tail.

Restoring my 1974 BMW R90S 900cc Motorcycle-tail1.jpg

Restoring my 1974 BMW R90S 900cc Motorcycle-tail2.jpg



Quote:
Originally Posted by veyron_head View Post
Extraordinary work! But very few pictures to see it's glory is frustrating! Please add more pictures.
There is a limit of 30 pictures and even then while writing captions and previewing, they turned to attachments. I have hundreds of pictures. I will try to post some of them here.
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