1962-1967 250cc BMW R27

By Jeff Dean
Tucson, Arizona, & Madison, Wisconsin

Above: a 1964 BMW R27 is the normal color of black with white pinstriping. Below: a 1966 R27 in optional Dover white paint with black pinstriping.

BMW Used to Manufacture Shaft-Drive Thumpers!

So you think that Bayerische Motoren Werke (BMW) only makes shaft-drive twins, triples, fours, and sixes, and more recently chain-drive singles and fours? If you do, you are wrong, combustion breath!

       

From the 250cc OHV R39, above left, of 1925 through the 1954 R25/3, above right, to the R27, BMW made shaft-driven thumpers ranging from 200cc (1931 R2) to 400cc (1932 R4) in almost as many permutations as its more famous opposed “boxer” twins. Most of the models, however, had bores and strokes both of 68mm, producing 247cc. Frame and suspension changes paralleled those of the twins

The last single-cylinder shaft-drive BMW motorcycle model made was the relatively powerful and elegant R27, a 250cc OHV vertical single with the only rubber-mounted thumper engine BMW ever produced. The engine pumped out 18 horsepower, the highest ever for a shaft-drive BMW single. BMW manufactured 15,364 R27s over the production years of 1960 through 1966 (some of the 1966 R27s were sold as 1967 models).

Click here for the 1966 BMW R27 Owners Manual

White 1966 BMW R27 R27 brochure


The vast majority of R27 motorcycles exported to the United States by BMW were black with white pinstriping. A few, however, were brought in by importer Butler & Smith in a color called Dover white, with black pinstriping, as shown on the 1966 R27 above, left. Why "Dover white?" Butler & Smith head honcho, Michael Bondy, had a 1942 Packard automobile in an off-white color called Dover white. Bondy sent a sample of this color to BMW AG in Munich and asked that it be duplicated. BMW did copy the color, and Bondy ordered fifty motorcycles in that color. Today, BMW motorcycles in original Dover white are a sought-after rarity.

The illustration above on the right shows the cover of a 1960s BMW R27 sales brochure.

Compared to other manufacturers' thumpers, what were some of its unusual features?

BMW never did run with the crowd and always struck out on its own path. This is evident in its R27. Its enclosed shaft final drive is extremely rare for a thumper, of course. But it also had a triangulated Earles front fork (named after English designer Ernest Earles); so the motorcycle had a front swingarm as well as a rear swingarm (right photo shows the Earles fork on an R27). 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 R27 engine's crankshaft was laid out fore-to-aft, not side- to-side; also a rare feature. This way, the crank 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 starter swung out sideways instead of parallel to the frame, so kick starting an R27 is a rather easy and danger-free affair.

What other BMW shaft-driven singles were manufactured after World War II?

In all, BMW produced six shaft-drive thumpers after the war, all with similar 250cc OHV engines. The first, in 1948, was largely a copy of the pre-war R23 and was designated the R24 (engine numbers 200 009 - 212 007). It was unique in that it had no rear suspension—the only postwar BMW so unequipped (see photo below). Thereafter, from 1950 to 1956, came bikes with rear plungers and front telescopics, all having exposed shaft drives and “bell-bottom” front fender skirts. These were the R25 (engine numbers 220 001 - 243 400), the R25/2 (engine numbers 245 001 - 283 650), and the R25/3 (engine numbers 284 001 - 331 705).

Above: a 1949 BMW R24.

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 the engine wailed away with 15 horsepower.

Based largely on the R26, the R27 added rubber mounts for the engine, which markedly reduced the R26's vigorous rider massages, and boosted horsepower by three to 18.

What are the specifications of the R27?

Here are the main ones:

    BMW R27 model engine serial-number range — 372 001 - 387 566
    Curb weight with fuel, oils, tools — 356 pounds (162 kg.)
    GVWR — 716 pounds (325 kg.)
    Fuel tank capacity — 4.0 US gallons (15 liters)
    Engine oil capacity — 2.6 US pints (1.25 liters)
    Engine oil type — SAE 40 (86°+), SAE 30 (32°-86°), SAE 10W30 (below 32°)
    Transmission oil capacity — 1.3 US pints (650cc)
    Rear drive unit oil capacity — 125cc
    Transmission and rear-drive oil type — SAE 90 gear oil or SAE 40 engine oil
         (depending on the year of manufacture)
    Wheelbase — 54.3 inches
    Overall length solo — 82½ inches (2090 mm)
    Handlebar width solo — 25.6 inches (660 mm)
    Overall height solo — 38.4 inches (975 mm)
    Saddle height — 30.2 inches (770 mm)
    Ground clearance — 4½ inches (115 mm)
    Maximum brake horsepower — 18 HP at 7,400 RPM
    Bore and stroke — 68mm × 68mm
    Cylinder capacity — 247cc (15 cubic inches)
    Spark plug — Bosch W240T1, Beru 240/14, or Champion L85
    Intake valve clearance, cold engine — .006 inches (0.15 mm)
    Exhaust valve clearance, cold engine — .008 inches (0.20 mm)
    Compression ratio — 8.2:1
    Top speed — 80 MPH (130 km/h) depending on conditions and wind
    Predicted mileage — 60 miles per US gallon (DIN 70030)
    Tires — 3.25 x 18, front and rear
    Battery — 6 volts, 9 Ah.
    Headlamp — 6 volts, 35/35 watts

Below are photos of a 1966 BMW R27 in the process of restoration by the noted BMW restorationists, Chris and Barbara Betjemann, of the Barrington Motor Works, in New Hampshire. They are currently preparing an R27 restoration and service manual to join their BMW slash-2 and slash-3 twins restoration and service manuals. Photos below by Barbara Betjemann.


Click here to read English R27 specifications from BMW A.G., Munich, Germany.


Below are pages from the 1960 BMW R27 brochure



Here is Allan's incredible R27 Restoration Story!

... and here is an R26 story by David Braun.

Click here for a 2012 Motorcycle Classics article on the R27.

       Click here for the large R27 photo in Motorcycle Classics.

Click here for the R27 article on Wikipedia.

Hier klicken, um den R27 Wikipedia Artikel auf Deutsch zu lesen.