BMW R 75/5

In September,1969 BMW introduced the /5 series of motorcycles, a new generation of machines which incorporated a number of features not found on earlier BMW models. The /5 series represented a major departure from the seemingly old-fashioned BMW tradition of black motorcycles with a reputation for sidecar hauling and not-so- impressive top end, machines now considered "classics" by BMW enthusiasts. The /5 series embodied BMW's efforts to appeal to the increasing sport bike market while at the same time not entirely turn off touring enthusiasts who had come to depend on the marque for long distance, reliable, and comfortable two-wheel travel.
The /5 series motorcycles were the first BMWs to be manufactured at BMW's West Berlin factory, a modernised factory which turned out aircraft engines during World War II. Production in Munich, where the motorcycles were previously made, was now focused on BMW's expanding automobile manufacturing.

MODELS
BMW offered three models in the /5 series, the primary variations in the models being the cylinder displacements. Actual displacement is 498cc for the R50/5, 599cc for the R60/5, and 745cc for the R75/5. The R75/5 was the first machine of that displacement offered by BMW since the end of World War II. Outwardly the three models are almost completely identical. Curb weight according to the 1973 owner's manual is 412 pounds for the R50/5 and 423 pounds for the R60/5 and R75/5 (less fuel). On the two larger displacement machines an electric starter motor is a standard feature; on the R50/5 it is optional. Concentric float carburetors are featured on the R50/5 and R60/5. The R75/5 uses constant vacuum (CV) carburetors with a 32mm choke. Bing is the manufacturer of both types.

VARIATIONS
It is in the model years that variations in the /5 series are most evident, notably in styling. Perhaps most infamous is the "toaster tank," a gas tank with chrome side panels introduced in 1972. This 4-1/2 gallon tank replaced the less flashy, original 6-1/4 gallon tank. A matching pair of chrome battery covers, with stripes painted black or blue came with the "toaster tank" machines. The nickname "toaster tank" was apparently originally used in the mid- to late 1970s in reference to the gas tank's resemblance to the kitchen appliance. Depending on one's opinion of the non-traditional styling, it can be considered complimentary or derogatory. One source (BMW: A Celebration) attributes the styling change to the appointment of Bob Lutz, the American automobile executive and motorcycle enthusiast, as BMW sales director. In 1973 a 4-1/2 gallon tank without chrome was offered on the /5 series bikes, an intimation that the switch to chrome was not a success.

Another styling change was the introduction of one-piece seat grab bars in 1973 to replace the two-piece bars on earlier models. More color schemes were offered as the production run of the /5 series grew older. In 1969 the R50/5 and R75/5 came with silver gray tank and fenders and blue pinstriping. The 1969 R60/5 was black with white pinstripes. In 1972 red with white pinstripes, black with white pinstripes, and white with black pinstripes were offered as standard. Optional metallic finishes included silver or mustard ("Polaris" or "Curry") with black pinstripes, and blue or green with white pinstripes.

Perhaps the most important structural design modification was the lengthening of the rear swing arm by some 50mm. This change was made to 1973 model year bikes. (Some bikes sold as 1973 models, however, did in fact not have the longer swing arm.) This gave riders increased clearance between their shins and the carburetors. It also improved straight-line performance of the bike, reducing wobble, and allowed more room in the frame for a larger battery. Long wheel base motorcycles were distinguishable from the earlier short wheel base by the black fuel lines and carburetor intake tubes which were originally silver.

Two less readily visible changes made in 1972 were the lightening of the flywheel and (on the R75/5) a lowered rear axle gear ratio. The width of the rear tire and rim was also increased on the R75/5.

Informal review of the /5 Internet group's bikes reveals myriad other variations in styling details such as tank and seat badges with or without black backgrounds, U.S. or Euro style handlebars, mirror stem lengths, absence or presence of U.S. Department of Transportation mandated reflectors, and even the color of the turn signal light indicator! Variety in the details is certainly one of th e joys of /5 ownership.