BMW RS 54...

Hey peeps! I figured before i went insane doing research all over the internets, that id ask my DTT brothers some questions.
I recently fell in love with the aforementiomed bike, and am thinking of building a replica for racing.
It looks to me like its a /5 style frame, with an old motor and really small seat.
Does anyone know if bmw made a 500cc /5? I would love to be able to run the bike in 500gp, even though i know i wont be competitive no matter where the bike ends up lol.
If not, would an older motor fit in a /5 type frame? I have mild fab skills ( cant build a frame, but dont mind cutting and modifying).

I would probably run conventional forks instead of the odd forks they ran back then.

Ive found a few /5 frames for 50 bux, thats why im curious if this is at all possible. O yea, heres a foto.


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THey made the R50 which was 500cc (the R60 was 600) from early 50's through mid 60's If memory serves.
Those "odd" forks are Earles Forks, standard BMW forks of the era, as BMW designed them all to be able to handle a side car easily.
You are right, the frame is not /2 but the forks could be.

From the small amount of research i did, they did make an r50/5, but it made like 32 hp. That wont be competitive in 500gp. Maybe ill just use a 750 and run in open gp or euro cup...after all it is just a replica.
I think my best bet tho is to use a /5 frame and just modify to suit. After looking at the earles fork, i kinda like it, but havent researched pricing yet.

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BMW made a sporting R50S sport bike in the early 60s, but it is so rare I doubt anyone could find one to buy even if they had the money. The regular R50 should be open to modification, as lots of guys raced it's 600cc big brother back in the day.

The R54 Rennsport was a race-only OHC Gp racer that was not generally sold to the public, usually raced by the factory or top GP stars of the 50s and 60s. I am sure they are going for around $100K now. I know where there is one stashed away that might be had for close to that, and I would buy it if I hit the lotto.

Protar made a Rennsport model kit, maybe you could find one on Ebay and then you would have something 3d to take a good look at. All BMWs had the swing-arm front fork before the late 60s, so if you wanted to be really authentic you should stick with one, nothing wrong with them at all, if a GP star could do well on them then it is good enough for you.

Good luck, it is certainly a worthy pursuit. I had a lot of chances at old BMWs over the years, but you just are not here long enough to do everything.

Been doing a bit of staring at my dads R100, looking for inspiration.
Question...does anybody know if the /5 swimgarms/final drives are interchangeable with disc and drum? Or do i need to buy one specific to drum? I hope that question is clear...

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Here's what I know.

The /2 and earlier motors did not have oil filtration proper. They literally have to be taken down to the crank every so often to clean out the sludge traps or "slingers" inside of them near the crank. The /5 motors were revolutionary by BMW standards and went basically unchanged up until the mid 90s. The drum swingarms and final drives are not interchangeable with disk parts. There are a few that have done some major machining to get the parts to match up. The first rear disk models that BMW offered were the monolever swingarms, and 90% of them were mag wheel bikes. There were a few early GS spoked disk rear wheels and final drives but they are very hard to come by. The /5 4 speed transmissions are clunky, but they are bulletproof. The early 5 speeds have known problems.

Airheads are amazing cruising motors, but be prepared to spend some money to get them up to competitive race standards. It can and has been done, but if you are used to building Japanese bikes, expect to spend at least twice the price for parts for the BMW equivalent. I love BMWs and especially Airheads. They are great machines, but when I am on one I want to ride it wherever my heart desires not race it. They sound like a Massey Ferguson tractor going down the road.

My favorite BMW factory racer is the 1939 RS 255 Kompressor. John Surtees rode it to several GP victories back in the day. It's an amazing machine.

I have decided to use primarily /5 parts for the whole build. I realize its going to cost lots of dollars to go fast, but im not rushing this build at all.

Im actually looking for drum rear, as the class i "want " to run in doesnt allow disc...hopefully the spoked drum wheels/parts are slightly easier to come by?

I have been in contact with a few guys, but am waiting for emails back.

Hopefully ill have a frame, swingarm, driveshaft and final drive soon...so i can hang it on my wall and stare at it haha!

Thanks for the response kiley! Oh yea, and i must agree, the kompressor sure is a beautiful machine! Heluva bike for its time

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Cool Tedd!

Can't wait to see what you get going man! Do yourself a favor and keep an eye out for a pair of 85 and up heads. Much better rocker design that will treat you much nicer when making it go faster than it's supposed to! ;D

Thanks for the "heads" up Kiley! Lol sorry couldnt resist. I know a few fellas who race bmw's so im guna talk to them next time we are racing. Try to get some tips/tricks

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Tedd,

The RS54 used a frame which is pretty close to a /5 frame. The subframe is different though. The original forks were unique and not taken from the /2 which came out later. It's likely that the /2 forks were inspired by the RS54 forks.

You can build an RS54 from new parts that are available. I can provide links if you are interested. Building one will cost you in excess of $25K.

I raced a BMW R75/5 in WERA and AHRMA racing for a few years. The bike was potentially competitive but the rider was not. The BMW is at a disadvantage though due to the drive shaft which consumes a good bit of power (less efficient than a chain). If you want to race a vintage BMW I recommend a /5 or /6 as the basis for your bike.

If I can help in any way let me know. Here's a picture of me on my R75 back a few years ago: