BMW R 27
The R27 model is a manufactured from 1960 to 1966 by BMW Motorrad single-cylinder four -stroke engine and the last model of the classical single-cylinder BMWs with shaft drive.
With this model, the era of the West German motorcycle construction in which a motorcycle was still the main means of locomotion ended. The emerging competition cheaper cars on the one hand and sporting Japanese motorcycles for recreational use on the other hand had the market for this kind of expensive motorcycles built in the former Federal Republic of Germany - in contrast to the GDR - come to an end. Their principal characteristics made the BMWs such as the R 27 at excellent travel machines with which tiring long distances could cover.
See also the article on the full rocker BMW.
Previous version
The predecessor of R 27 was the model BMW R 26 with 11 kW/15 hp and at substantially the same full swing frame with cardan shaft drive. From this, the R27 is different with a strengthened on 13 kW/18 hp four-stroke engine in order to meet the competition of the former NSU Max.
Design Features
The frame is of welded steel tubing and is suitable because of its great stability for the sidecar. In its design, it is the far more rapid two-cylinder BMW almost equivalent, but oval drawn - have down tubes - instead of circular.
The R 27 never had side-mounted ball heads for the sidecar standard. It was always a special subframe needed. The sidecar S 250 of Steib is a fitting Beiwagenmodell. The sidecar requires special gear ratio of Kardanantriebes that could be opted for BMW: With a shorter reduction reduces the top speed, but remain traction and acceleration get far sometimes.
The fenders and the tank are made of sheet steel, aluminum rims and hubs. The engine block is how the transmission and the Kardangetriebegehäuse, made of cast aluminum. While the previous models, the BMW R 25/ 3 and the BMW R 26, only had rubber bushings to mount the motor in the housing for two half shafts, is the driving suspension of the R 27 designed complex: motor and gear are on two rubber-metal elements ( elastomeric bearings ). The engine has the cylinder head a fifth breakpoint with another rubber-metal element. Thus, the motor -gear unit is mounted entirely in the rubber. Also the muffler is mounted elastically, to prevent vibrations from the frame. Mechanical noise and vibration from the engine and transmission are not transferred to the chassis and the driver. This was the R 27 to a for that time very quiet and low-vibration type of motorcycle. This feature of low vibration makes all BMW for this design principle to popular machines.
Motor
The motor is equivalent to previous models BMW R 25/ 3 and BMW R 26 is a longitudinally mounted single-cylinder four -stroke engine with side mounted mid high cam shaft and adjacent to the cylinder in chrome pipes out bumpers. This actuate the rocker arms in the cylinder head, which in turn hanging on and exhaust valves ( OHV engine ). The rocker arms are mounted as the piston pin in bronze bushings, the crankshaft bearings. The camshaft is driven by an oil-immersed simplex chain from the crankshaft. The oil pump, a simple gear pump, is located in the oil pan. It is driven via a worm gear ( reduction ) of the camshaft.
On the front tail shaft sits behind the aluminum cover the substantially water- tight encapsulated alternator. BMW had outsourced the R 27 the governor and the Contact Point for the ignition before the camshaft. The charge controller of the 6 -volt direct-current electric machine is located beneath the tank, the 6-volt lead-acid battery after a lid on the left side.
On the rear tail shaft sits the heavy flywheel, which shows the Zündeinstellmarkierungen in the inspection hole. The flywheel absorbs the single dry. The clutch is operated with a thrust of a pressure rod, which extends through the hollow main shaft.
The carburetor is a classic 26er Bing carburetor float chamber with a conical nozzle needle in the round slide. The air filter element is located on the right side cover. With the first machine ( to the serial number 379 580 ) is the same washable oil-impregnated wet air filter was used as for the R 26, and then a dry air filter element can be cleaned with compressed air, however, needs to be replaced later.
Due to the larger cooling fins on the cylinder and cylinder head were cooling problems, some of which were observed with the predecessors in the sidecar operation, no longer.
Drive
The R 27 has as its predecessors fußgeschaltetes a four-speed gearbox with dog clutch, idle display and Kickstarter. An often -to-find in the earlier BMW motorcycles additional manual shift lever was previously eliminated already at the R 25/3. The powertrain requires the transmission output because of the movable swing an angularly movable and length- tolerant torque transmitting member. To a four-hole elastomeric disk ( flexible disk ), is pushed on Zweifingerflansch the transmission that transmits the torque of the transmission output shaft to the propeller shaft. An aluminum cap, which is attached to the gear, surrounds the flexible disk. The propeller shaft to the rear wheel runs dry in the steel tube swingarm accommodates the aluminum housing of the angular gear with bevel gear pair for 90 ° deflection at the end.
The entire drive train is sealed against dirt and moisture and to this rare oil change maintenance-free, as opposed to the then almost always non-enclosed chain drives.
Landing gear
The chassis is a welded double tube steel frame. It corresponds to the modified engine storage, the BMW R 26 on the front wheel is pushed a long arm with two spring struts and oil filled shock absorbers the wheel location. The rear wheel is out on a long swing arm, also sprung at two spring struts with integrated oil -filled shock absorbers and damped. The rear spring preload can be converted to use with pillion in two stages. The chassis proved to be superior to competing models of the time until completion as an equal. A special feature is the prepared to the last detail sidecar mode option: The front long swingarm can be changed with a repluggable threaded rod for ease of tractability for towing trailers on short follow-up. By means of two additional bolts sight under the steering head, which allow the adjustment of the front bumper, other upper pivot points can be used with respect to the steering geometry for greater ground clearance.
This type of front suspension has not been exceeded for the sidecar until today, over fifty years after the first appearance of the competition. Also conversions of modern, much stronger motorcycles to use for the sidecar exactly the same design principle of pushed long swingarm.
For the operation of the solo motorcycle, however, was always criticized on the front long arm that you move high masses about the steering axis, resulting in reduced maneuverability result. The great successor models had taken the front rocker then a telescopic fork - and also the export models of the " full rocker BMW " for the U.S. had since 1965, coinciding with the construction freeze of R 27, already again a telescopic fork - the same, but crucial improved front suspension, with the then also the successor models were fitted for all markets. Consequently, BMW no longer were these models ( the U.S. machines from 1965 and the " / 5 Series " series from 1969) released for towing trailers.
End of construction
The BMW R 27 was produced in a difficult year for the German motorcycle industry time. The motorcycle companies sought refuge ³ in other products or in the production of machines to 50 cm. At the same crowded, at first often underestimated, Japanese manufacturers on the German market, especially Honda. This resulted in a re-orientation of the market. The bike evolved from a pure transport hobby vehicle that was operated next to the car ownership. To date, January 1, 1965 about 29,000 motorcycles were in the Federal Republic of Germany registered yet, but it already about five percent of Honda. At this time, the R YDS -2 saw 27 with the Honda CB 250 and Yamaha opposite with 22 hp and 24 hp for a more powerful and of a sporty image embossed competition. The R 27 suffered from high production costs, which is not significantly below those of the two-cylinder boxer engine.
For the R 27 is therefore at BMW was no successor in the class up to 250 cc. A planned renewal called R 28 ( with telescopic forks of the later BMW-/5er-Reihe ) was stopped before its launch, and the R 27 further built about three years, until the / 5 series of two-cylinder appeared and BMW full swing arm bikes completely from the new machine market disappeared.
A total of 15,364 units were produced from 1960 to 1966 ( serial numbers 372001-387364 ), of which apparently is still an amazing number ready and will be cherished by collectors hand.
The official final selling price amounted in 1966 to DM 2670
BMW motorcycle as authorities
The R27 model was generated ( 6009 Fir green RAL ) for the German Armed Forces Bundeswehr in standard finish, the German Red Cross in ivory paint finish and the police authorities in police - green, and used mostly for training purposes. Tens of thousands of soldiers in the 1960s and 1970s learned motorcycling on BMW R 26 and R 27
R 27 as a vintage machine
The R 27 is a stable value vintage motorcycle. The sharp rise in recent years, prices for full- swing two-cylinder also secure the resale value of R 27 Prices for roadworthy approvable R 27 move at 3,500 euros ( 3/2006), about four times the previous original price. For like-new tip specimens with sidecar, however some prices 8000-10000 euros are required.
The acquisition of an old R 27 is a harmless affair given the limited technology. Brakes, transmission, shaft drive and frame are easily; any electrical and engine problems can be solved quite cost effective in most cases. Also, the supply of spare parts, sometimes even from the factory, partly specialized classic car dealer quite well. Again and again, just for BMW motorcycles of the 1950s and 1960s " NOS " parts - new old stock, things that came as new parts to the dealer and for decades unused camped.
On the other hand, most sought not " brand new " refurbished machines, but well-maintained bikes with few signs of wear, with the so-called "patina" and even the first coat dress are.
Others
The ambivalence of BMW at that time and the search for marketable vehicle solutions can also be seen in the use of this same single-cylinder engines are used in the small car BMW Isetta. In the Isetta which in principle has remained the same single-cylinder base engine is operating, only supplemented by a forced air cooling and equipped with a special alternator, which also serves as an electric starter. Power hungry, single-cylinder motorcycle owners took advantage of some of the optional larger motor components of the Isetta 300 ( the crankshaft, piston and cylinder ) to get its R 26 and R to help to be a little more displacement and output 27. Even entire Isetta engines along with fan cooling and electric starter found sporadically in the way the bike full swing Suspension: possibilities of the modular design and the ambitious tinkering. Who was driving motorcycle at that time, completed, most likely, all repairs and maintenance work itself
The BMW R 27 was the last BMW single-cylinder model before publication of the completely newly designed and manufactured in Italy 650 BMW Enduro. Your construction fell in the 1960s, and thus in the great downturn of the German motorcycle market.
Technical data of the R 27
- Full swing frame with suspension of the motor gear unit in elastomeric bearings