• Ex-works Grand Prix racing motorcycle
• The pinnacle of Grand Prix machinery in the pre-war era
• One of only seven survivors of no more than 10 built
• Offered from a private collection
• Requires recommissioning/restoration

The RS 255 Kompressor is of immense significance in the history of BMW motorcycles, for it was while riding one of these exotic works specials that Georg Meier became the first foreign winner of the Isle of Man Senior TT in 1939, his achievement marking the pinnacle of pre-war success for a firm that, remarkably, had not built a motorcycle of its own until 1923. Originally an aero engine manufacturer, Bayerische Motoren Werke (BMW) had come into being in July 1917 when the Bayerische Fluzeugwerke (BFW) company was reorganised. BMW's engines had proved their worth time and again in aerial combat in WWI, but on the cessation of hostilities the firm had no option but to seek other work, hence the switch to motorcycles.

As far as competition was concerned, BMW would not be ready to challenge the British factories - which dominated international motorcycle racing - for some time, choosing instead to concentrate its efforts on speed records. It was in pursuit of increased speed that BMW turned to forced induction, attaching a kompressor (supercharger) to works rider Ernst Henne's 750cc R63 in 1929, the result being a first world record for the German company at 133.8mph. Henne would hold the world motorcycle speed record for most of the 1930s, leaving it at 173.7mph in 1937, a figure that would not be bettered until 1951. From 1935 onwards Henne used a 500cc supercharged (kompressor) twin, and this forced induction technology was first applied to the factory road racers that same year. Whereas the R63 had been a pushrod overhead-valve design, the new works racers were powered by an engine boasting twin overhead camshafts in each cylinder head, driven by shaft-and-bevel gears from the crankshaft. The position of the blower changed too, moving from atop the gearbox to the front of the engine. Engine casings and wheel hubs were cast in lightweight magnesium. BMW's spirit of innovation also extended to the racers' cycle parts: the frame was of welded tubing; telescopic front forks were fitted from '35, and friction-damped plunger rear suspension from 1937.

Success at the Isle of Man TT was the ultimate achievement in motorcycle sport in the pre-war era, a fact that BMW could no longer ignore. The company's first official venture to the Island came in 1938, when Englishman Jock West finished 5th in the Senior race. Meier had been sidelined by a mechanical problem and forced to retire. The race was won by Norton's Harold Daniell. Before then West had ridden a BMW RS 255 to victory at the 1937 500cc Ulster Grand Prix held on the Clady Circuit, his win marking the first time that a non-British motorcycle had won the 500cc event at the Ulster. West returned the following year to win the 1938 Ulster GP again, but it was not until 1939 that it all came together with Meier's historic Senior TT victory.

Georg Meier had started his motorcycling career with the Bavarian State Police and later became a member of the Bavarian Police Team, competing with distinction in long-distance endurance trials. Meier's successes led to him being recruited by the German Army for whom he rode in the 1937 ISDT. Despite Meier's talent the Germans lost to the British on handicap, but his sterling efforts led to an offer from BMW. Riding an RS 255 Kompressor, he started the 1938 season by winning the Eilenriede Race at Hannover, setting race and lap records. That year Meier went on to win the 500cc races at the Belgian Grand Prix at Spa-Francorchamps, the Dutch TT, the German Grand Prix at the Hohenstein-Ernstthal (or Sachsenring) road course, and the Italian Grand Prix at Monza. At the season's end Meier was crowned European Motorcycle Champion in the 500cc class.

By 1939 Meier was a sergeant-instructor with the Military Police and continued racing for the factory BMW team during his periods on leave. At the 1939 Isle of Man TT the RS 255 racers appeared little changed from the previous year. Much of the opposition was new, but at 306lb (139kg) the BMWs were the lightest in their class. Meier and West ran away from the field from the start of the Senior race, the German leading from start to finish and winning at a record average race speed of 89.38mph. In a convincing show of dominance, West finished 2nd, although the team's post-race celebrations were muted following the death in practice of Karl Gall, who had crashed at Ballaugh Bridge.

Bonhams has consulted the BMW Archives in Munich and they advise that this motorcycle's individual parts and details look original: e.g. engine, kompressor and transmission housings, cylinders with heads, rear-axle drive, frame, fork, tachometer, telescopic fork, handlebars. However, they cannot say what racing history this motorcycle has. BMW do not know the exact number built, although it is assumed that it was no more than ten. Seven examples are still known to exist. Notable features of this particular RS include the following:

Shaft drive numbered 35/8
Alloy fuel tank
Drillastic saddle
Modern fastenings throughout
R Muhle & Sohn Glashutte 8,000rpm rev counter
Weinmann rear wheel
RHS Magura control lever

The motorcycle itself dates from 1938/39 but these machines were modified in the first years after the war. Germany was excluded from international sporting events until 1951, which is why BMW were restricted to competing in national motor sports championships at first, and why they were not directly affected by the (international) ban on supercharged engines. As early as 1947, the pre-war models were being used for racing again and Georg Meier won the German Championship. The RS was frequently modified in detail, while there was a noticeable change in 1949 when a leading-axle telescopic front fork was adopted (replacing the inline-axle type of pre-war days), which can been seen on this example. It should be noted that various castings show corrosion typical of magnesium. On the one hand, this speaks for their originality, but on the other it indicates that they must be very carefully examined for suitability of use before the motorcycle is used again. Some engine gaskets appear to have deteriorated (some gaps are visible) and the fork gaiters are torn.

Clearly unused for a considerable period of time, the RS will require careful recommissioning, or potentially more extensive restoration, before further use and thus is sold strictly as viewed (the engine turns over). Accordingly, prospective purchasers must satisfy themselves with regard to the condition, completeness, authenticity and compatibility of this Lot's component parts prior to bidding.

This sale represents an almost certainly once-in-a-lifetime opportunity to own one of the most coveted motorcycles of all time: the very pinnacle of Grand Prix machinery in the pre-war era and the crowning glory of BMW's technological prowess.