The 247 cc BMW R27, introduced in 1960, was the last shaft-driven, single-cylinder motorcycle

Motorcycle

A motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...

 manufactured by BMW

BMW Motorrad

BMW Motorrad is the motorcycle brand of the German company BMW, part of its Corporate and Brand Development division. The current General Director of the unit is Hendrik von Kuenheim....

.

History

After World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, the Potsdam Agreement

Potsdam Agreement

The Potsdam Agreement was the Allied plan of tripartite military occupation and reconstruction of Germany—referring to the German Reich with its pre-war 1937 borders including the former eastern territories—and the entire European Theatre of War territory...

 of the USSR, USA, and the UK, prohibited BMW

BMW

Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...

 Aktiengesellschaft (AG)

Aktiengesellschaft

Aktiengesellschaft is a German term that refers to a corporation that is limited by shares, i.e. owned by shareholders, and may be traded on a stock market. The term is used in Germany, Austria and Switzerland...

 from building motorcycles. Later, this ban was lifted and in 1948 BMW produced its first postwar motorcycle, the 250 cc R24, which was based largely on the prewar R23. It was the only postwar BMW motorcycle produced without a rear suspension

Suspension (motorcycle)

A motorcycle's suspension serves a dual purpose: contributing to the vehicle's handling and braking, and providing safety and comfort by keeping the vehicle's passengers comfortably isolated from road noise, bumps and vibrations....

. BMW introduced the R25 model, with plunger rear suspension

Swingarm

A swingarm, or "swinging arm" is the main component of the rear suspension of most modern motorcycles and ATVs...

, in 1950. The last of the plunger models, the R25/3, was introduced in 1953.

R26

In 1956 BMW introduced a completely revamped thumper, the R26 (engine numbers 340 001 – 370 236), with improvements paralleling those introduced at the same time in the boxer twins. The R26 came with an enclosed drive shaft, rear swingarm, and front Earles forks. A new headlight nacelle came with a sliding black plastic over the ignition key, and the “bell-bottom” front fender was dropped along with the mechanics' hand shifter. The engine of the R26 was bolted directly to the frame, and produced 15 hp.

R27

Based largely on the R26, in 1960 the R27 added rubber mounts for the engine and boosted power to 18 hp. The R27's 250 cc OHV

Overhead valve

An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...

 vertical single was the only rubber-mounted thumper engine BMW ever produced, and was their last shaft drive single-cylinder motorcycle. The engine pumped out 18 hp, the highest ever for a shaft-drive BMW single. BMW manufactured 15,364 R27 models (engine numbers 372 001 – 387 566 ) over the production years of 1960 to 1966. Some of the 1966 R27 models were sold as 1967 models because dealers in those years often would assign dates to BMW motorcycles when they sold them, and not necessarily when they were manufactured.

BMW did things differently from other manufacturers. This is evident in the R27. Its enclosed shaft final drive is rare for a single cylinder motorcycle. But it also had a triangulated Earles front fork

Motorcycle fork

A motorcycle fork connects a motorcycle's front wheel and axle to its frame, typically via a pair of triple clamps. It typically incorporates the front suspension and front brake, and allows the bike to be steered via handlebars attached to the top clamp....

 (named after English designer Ernest Earles); so the motorcycle had a front swingarm as well as a rear swingarm. When you squeezed the front brake lever hard not only did the front end not dive, it actually rose slightly. Thus, braking was a very steady activity, though the brakes were weak by today's standards. The engines crankshaft was laid out fore-to-aft, not side- to-side; also a rare feature. This way, the crank

Crankshaft

The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

 and the final shaft were in line, and drive forces did not have to be run through a set of 90-degree gears. Also, the kick start

Kick start

Kick start refers to a method of starting an internal combustion engine by pushing a ratcheting lever with one's foot. Kick start mechanisms were almost universally a part of motorcycle engines before the mid-1970s, and were phased out of production over the next twenty years or so as electric...

er swung out sideways instead of parallel to the frame.

Technical data

	R27
Engine Numbers	372 001 – 387 566
Design	Single cylinder with driveshaft
Engine	4-stroke, 2 OHV Overhead valve An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...
Transmission Transmission (mechanics) A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...	Four-speed, left foot
Model years	1960–1966
Number manufactured	15,364
Bore	colspan= " 1 " align= " center " | 68 millimetres (2.7 in)
Stroke	colspan= " 1 " align= " center " | 68 millimetres (2.7 in)
Capacity	247 cc
Power	18 hp @ 7400 rpm
Compression ratio	8.2:1
Fuel efficiency	60.3 mpgus DIN 70030
Maximum speed	81 mph (130 km/h) / with side car 56 mph (90 km/h)
Wheelbase	54.3 in (1,379 mm)
Curb weight Curb weight Curb weight or kerb weight is the total weight of a vehicle with standard equipment, all necessary operating consumables , a full tank of fuel, while not loaded with either passengers or cargo.This definition may differ from definitions used by governmental regulatory agencies or other...	colspan= " 1 " align= " center " | 357 pounds (161.9 kg)
GVWR Gross vehicle weight rating A gross vehicle weight rating is the maximum allowable total weight of a road vehicle or trailer when loaded - i.e., including the weight of the vehicle itself plus passengers, and cargo....	colspan= " 1 " align= " center " | 716 pounds (324.8 kg) / with side car 1058 pounds (479.9 kg)
Tires front & rear	3.25 x 18
Battery	6 volt, 9 Ah.
Tank capacity	3.96 US gallon (15 liter)
Engine oil capacity	2.6 US pint (1.2 liter)
Transmission capacity	650 cc
Rear drive capacity	125 cc