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Friday, December 28, 2012

R51/75 Racebike

Some time ago I posted some pictures and info about the curious post-war BMW's sometimes refered to as R51/75.  These are plunger frame chassis fitted with a war-time 750 cc motor.  Most often these are seen with a sidecar attached, but solo forms exist.

I have in my collection such a bike, built in Germany in 1950.  It somehow found its way to the states, though the circumstances remain a mystery.   The history of my bike is known back to 1972 when a friend and former BMW dealer owned it.  There have been five owners since.  Below are some pictures of the bike over the years.

The R51/75 circa 1972 as seen from the left. (Photos from Duane Ausherman)

The R51/75 circa 1972 as seen from the right.

Art Pels astride the R51/75 at an AMF race at the Presidio (San Francisco) 1972. (Photo courtesy of Art Pels)

The bike as it exists today.  The rear fender was changed to a racing style, courtesy of Brian Hilton in the early 1980's.  The sidecar style Amal Fischer carbs have been exchanged for Dell'Orto's.  An R5 transmission case has been utilized.  (The original racing gear set was transferred from the old housing.)


I was recently contacted by the son of a former owner of my motorcycle who has shared some interesting history and photos.  I am awaiting more details, but will attach one of the photos that has been shared with me.

The bike as it appeared in August of 1960.  It was registered in Michigan and being ridden by a Mr. Hummel and his wife.

Nearly identical bike, with sidecar, being raced in Ingolstadt, Germany 1952.  Notice the drilled hubs.


Sunday, November 18, 2012

Post-war plunger toolkit

A fellow collector was recently asking for pictures of an original, post-war plunger frame bike toolkit.  Attached below are photos of an original kit that came with my 1952 R68.  The same would have been supplied with R51/3 and R67.

The bag is a canvas material and sort of grey-green in color.

Wrench size ranges from SW 6.5 to SW 41.  Notice what wrench size is absent?  No 13 mm.  The reason being in 1952 the DIN for an M8 was still SW 14 for the nut and bolt. 

The wrenches are marked "Walter".  The logo is similar to the Volkswagen logo, only with two crossed hammers forming the "W".  The large wrench is a "Hazet" and the small carb wrench is not marked. 

The pliers are marked "Rahsol" and the pin wrench has a BMW "Zeichnungsnummer" or drawing number.

For those not familiar with the older BMW numbering system, the above number isn't a part number, and its not a casting number.  It is a drawing number, with some logic to it.  251.3 is the frame type, that corresponds to R51/3 and R67.  The number 97 refers to the "group".  In the old BMW system, group 97 is "tools".  The 017 is the number of a specific tool, in this case 017 is the pin wrench.  Finally 04 corresponds to the size of the drawing, in this case 04 means that the drawing was A4 paper size. 

Sunday, October 21, 2012

One fast door handle!

On a recent trip to the Netherlands a friend of mine and I traveled to a small, out of the way motorcycle shop.  In the upstairs loft was a small, private museum with an array of collectibles and motorcycles of varing age and marques.  Amongst the collection was this shop made set of doorhandles.  Yes, those are genuine RS54 Rennsport con rods adorned with BMW roundels.

Sunday, June 17, 2012

Concorso d'Eleganza Villa d'Este

Concorso d'Eleganza Villa d'Este

Since 1929 the Villa d'Este in Cernobbio, Italy, on the banks of "Lago di Como" has played host to the Concorso d'Eleganza.  As has been the case with several other high profile automotive events, the Concorso has recently added motorcycles to the venue.  2012 was the second year that motorcycles have been shown and displayed in tandem with the cars.

This years event, held Friday May 25th through Sunday May 27th, was a smashing success.  The Concorso's main sponsor is BMW, and they spared no expense to make sure that the event was top notch.

View of the dock at Cernobbio exiting from the water taxi.
The Concorso is actually two events at two venues, combined in to one.  The Villa d'Este is a very exclusive and historic hotel at the waters edge.  While able to accomodate the fleet of very expensive and historically important cars that are invited each year, along with their owners, the venue lacks the size to allow the general public to participate at the hotel.  Therefore a private showing and judging of the cars is held at the Villa d'Este on Saturday.  Then early Sunday morning, the cars a brought the few hundred meters through the quaint town of Cernobbio to join the motorcycles for display at the Villa Erba.

Villa Erba as viewed from Lago di Como.
 The motorcycle exhibition takes place throughout the weekend at Villa Erba.  BMW, primary sponsors of the Concorso, erected an elaborate stage for the bikes on the grounds of the Villa.  The impressive structure consisted of a steel frame with wooden floor and stretched canvas ceiling.  A tremendous amount of time, energy and money went in to erecting the structure which is only used for the one weekend!  Needless to say, an army of workers from BMW is required to set up and remove not only the infrastructure, but the motorcycles themselves.

The special motorcycle exhibition erected by BMW for the event at Villa Erba.

Inside the exhibition hall on the grounds of the Villa Erba was a special exhibition of BMW racing cars and motorcycles.  The bikes on display included an RS54 Rennsport Gespann, Butler and Smith R90S, R5SS and landspeed record winning Kompressor.  Less vintage, though still interesting, was the Marco Melandri S1000RR world superbike and the BMW Italia Goldbet S1000RR. 


R90S Butler and Smith Superbike

RS54 Short Stroke Sidecar

1937 500cc 100hp World Record Machine piloted by Ernst Henne

Marco Melandri S1000RR World Superbike

BMW Italia S1000RR
The motorcycle exhibition of invited machines was held outdoors in a beautiful pavillion.  In true BMW style, everything was professionally laid out.  The bikes were all represented by plaques indicating the make and model.  In typical German fashion, representatives from BMW Classic spaced out the motorcycles using a tape measure!  A red velvet rope kept curious onlookers from getting too close to these exceptional machines.  (This was especially important as the  MV Agusta in the concepts and prototypes category was a lifesize clay rendering.)

Accompanying the show was a wonderfully illustrated hard cover book outlining the themes of the various classes as envisioned by motorcycle enthusiast and author Stefan Knittel.

As my interest is in BMW motorcycles, I spent considerable time pouring over the details of the 1939 Kompressor that was on display. 

Sebastian Gutsch from the BMW Classic team stands by in his togs as he gets ready to ride the Kompressor from Villa Erba to Villa d'Este.

And now for a special treat.  The sound of a BMW prewar Kompressor.........

Sunday, February 5, 2012

BMW Earles Fork Performance Parts

As has been documented and discussed elsewhere, there was a short hiatus after the war before BMW was allowed to produce motorcycles once again.  Indeed the first post-war twin didn't appear until the 1950 twin cam R51/2 was introduced.  It was, in essence, a slightly modified version of the prewar bike of similar name.   While a sporting bike, it wasn't a "sport bike".  And a short two years later, the larger displacement R68 became the crown jewel of the BMW civilian line up, and the twin cam motor was unceremoniously dropped.

With its 26 mm carbs, magneto ignition and higher compression pistons, the R68 didn't disappoint.  After its 3 year tenure, the motor platform was transitioned to the R69.  In essence, the motor saw little change, but of course the frame was radically different.  The rear of the bike gained a true oil dampened suspension, in place of just springs.  And the Earles Fork was transitioned from the RS54 racebike, to the civilian model. 

As owners of any Earles fork model know, the geometry of the front end was meant to counter act the normal dive sensation one feels when applying the front brake to a more traditionally forked bike.  In fact the front end on an Earles equipped bike rises slightly.  The overall geometry of the bike and front end was the reason the bike was so popular with the "seitenwagen" crowd. 

Now of course when you think of 60's performance bikes, perhaps BMW isn't the first to come time mind.  Nortons, Triumphs and Ducatis often lead the way in this regard, however there were plenty of "weekend warriors" looking to get extra performance from there Bavarian machines.  Enter the after market suppliers.

While there were a host of offerings available to make your bike look cool, or to make it more comfortable for a long trip, there were also companies offering aftermarket performance parts with the promise of more speed.

Once such company was Bowman.  They supplied cast aluminum deep sump oil pans, adding extra oil capacity and the promise of cooler oil.  (A side benefit was that unlike the stock sheet metal pans, they weren't prone to warping and hence leaking when overtightened.).  In addition, Bowman offered an aluminum flywheel.  By decreasing the rotating mass of the motor, shifting was smoother, and less clunky.  And arguably the engine revved up faster.  Bowman also supplied pistons and rings. 

Early on the 1950's the firm of Ernst Hoske supplied all manner of performance parts.  In fact in one of their early catalogues they offered a kit, by which a handy owner could transform any pre or postwar R51 twin cam bike into an R51RS replica by swapping out the timing chain for gears, and replacing the front engine cover with a total loss version.  Of course the battery coil ignition was dropped in favor of a magneto.  The kit included new cams, valves and valve springs.  With the addition of a tach drive, and tachometer, the average Joe could be off to the weekend races!  Of course this transformation wouldn't be complete without some Hoske full width racing hubs, and a sportier tank.  A full transformation would necessitate swapping out the transmission gear cluster or a more sporting version as well.

As time went on, Hoske, himself an ex-racer seemed to concentrate more efforts on after market fuel tanks, and less on true sport or racing parts.  In fact his catalogue from 1965 offers six different gas tanks.  Also on offer was a crank driven tachometer, an aluminum extension for the oil pan to add capacity, and an oil temperature gauge.  Also offered were Rennt├╝tenform mufflers, clubman or clip on handlebars, and a sport front fender.  Arguably, few of the above parts offered a true speed advantage.  Still for sale, however,  were sport cams, and larger valves, by which one could hope to squeak out perhaps a couple extra horsepower. 

The third name that comes to mind is the firm of Schorsch Meier.  With a win in the senior TT at the Isle of Mann in 1939, Meiers legacy was cast.  He parlayed his fame into a successful post war motorcycle and car dealership.  In fact some of his parts, such as the 6.5 gallon sport tank, and the bench seat were adopted by BMW and included as factory options when ordering a new motorcycle from Munich in the late fifties and sixties.

For further discussion of 1950's sport parts offered by Meier, see this prior post.

It seems today, little has changed.  While some guys are perfectly happy with a stock version Slash2, still others yearn to deck their bikes with performance bits and modifications, and are willing to pay for the privelege of doing so.  Large Hoske tanks still command a premium, and the 6.5 gallon Meier sport tanks are almost always preferred over the smaller 4 gallon versions.