1939 BMW RS 255
Supercharged racing motorcycles were all the rage in the 1930s. BMW's Kompressor flat twin claimed speed records, gold medals and TT accolades just before the outbreak of war...
BMW started experimenting with supercharging their flat twins in the late 1920s and a decade later had refined their Kompressor works racer into a world-beater. The DOHC twin used a huge Zoller blower built onto the front of the crankcases, with the cams driven by a single timing shaft. The remarkably reliable and versatile set-up boosted output of the 493cc engine to give 80bhp at 8000rpm, which translated to a top speed of 140mph on short circuits.
When fettled for outright straight-line speed, the 66mm by 72mm supercharged motor was capable of generating 105bhp at 8000rpm for land speed record attempts. Suitably swathed in an aluminium body shell, it claimed the motorcycle speed record on an autobahn near Frankfurt at 159mph in 1935; then 168mph in 1936, and finally 173.681mph in 1937 -a record which stood unbroken until 1951.
Meanwhile, the supercharged BMW started to enjoy success on short circuits and in road races. Kitted out with an unusually advanced tele fork front end in 1935 (followed by plunger rear suspension in 1936 on some machines); a foot-shift four-speed gearbox and weighing a smidgen over 300lb, the Kompressor 500 won the 1937 Ulster Grand Prix - thanks in part to a superb ride by pilot Jock West. It also proved competitive in the ISDT competitions of the mid-30s, which is when Schorsch (who soon became known as 'George') Meier first put it to good use in helping to secure a team Gold medal.
However, the roaring Beemers took a couple of seasons to find their feet on the Isle of Man. Jock West was again loaned a works Kompressor - the first official BMW machine to enter the TT - and came sixth in the Senior in 1937. In the 1938 TT, the best that the works team of three riders could manage was fifth place in the Senior when George Meier was forced to retire thank to a faulty spark plug and an accident sidelined Karl Gall. Interestingly, Jock West was riding a Kompressor with the earlier rigid frame while Meier and Gall were equipped with the new sprung model, which initially proved harder to manage on the demanding Island course.
Finally in 1939 the Kompressor BMW lived up to its full potential. Meier became the first foreign rider to secure the top step at the Isle of Man Senior TT while Jock West (who, incidentally, was the first English rider to join the BMW works team) secured second place. These successes were a particularly bittersweet accomplishment as the third member of the BMW team, Karl Gall, was fatally injured in practice. That accident served to underscore Meier's performance. He led from the start to the chequered flag, and set a new lap record on his initial circuit. With two pit stops, he completed the course in two hours and 57 minutes at an average speed of 89.108mph.
Said Meier; 'What I really wanted to do most at that point was literally kiss and hug my wonderful machine with its white-and-blue colours on the tank which, apart from all those flies on the wind deflector, still looked brand new, without the slightest trace of oil or any signs of the incredible race we had just been through.'
When Jock West crossed the line some two minutes later, he was more than half a minute ahead of privately-entered Norton rider Freddie Frith. The BMW one-two was a propaganda coup for the Nazi administration - which had also sponsored teams from NSU and DKW to attend the 1939 TT. To be fair to Norton, they did not enter a works team in the 1939 TT, concentrating instead on tooling up for war production. And indeed, just three months later, Britain and Germany were at war.
Hostilities took centre stage - then after the war, the mighty Kompressors raced again as some of the works machines were claimed as war reparations while Meier himself campaigned one in German post-war championships. When Germany was once again allowed to participate in international motorcycle racing, supercharged engines had been barred, and so the Kompressor never competed again on the world stage. John Surtees once said that the Kompressor BMW 'rightly deserves a place as being one of the all-time greats of motorcycle Grand Prix racing.'
Now four Bavarian racers will go under the hammer at Bonhams auction in Las Vegas in January 2013, with a 1939 RS (rennsport) 255 Kompressor leading the pack. The RS 255 is a documented supercharged 1939 engine mounted in an authentic 1951 frame, and it's accompanied by a 1954 BMW RS 254, a 1954 BMW RS 254 outfit and a 1956 BMW RS 256.
The last time Bonhams auctioned a similar machine was in 2010, when a very rare, factory prepared 1939 BMW RS R51 sold for US$130,200. Likewise, this quartet of German racers is expected to attract significant interest, particularly the Kompressor. The sale takes place on 10th January 2013 at Bally's Hotel and Casino on The Strip.
Text by Realclassics.co.uk