BMW R75/5

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One R75/5 "Toaster" reflected in another

The R75/5 is a 750cc boxer twin BMW motorcycle that was manufactured in Berlin, Germany, by the Bayerische Motoren Werke (BMW Aktiengesellschaft).

1 History
2 Technical Data
3 Related Wikipedia Sites
4 External links

[edit] History

For the 1970 model year, BMW Aktiengesellschaft (AG) entered the age of modern motorcycles with three new BMW models having engine capacities of 500cc (R50/5), 600cc (R60/5), and at the top of the line 750cc (R75/5). All so-called "slash-5" models were manufactured at BMW's factory in Berlin, BMW having transfered all motorcycle production there from Munich in the late 1960s. BMW had stopped production in Munich of the last “Slash-2” models, with their Earles forks, kick starters, 6-volt electrical systems, woeful brakes, and frames that descended from prewar BMWs (but bikes that still evoke nostalgic passion in some BMW enthusiasts). The new, “Slash-5” series of BMWs offered 12 volts and electric starters, as well as the retained kick starter, telescopic forks, and improved brakes. BMW also introduced with this model nonmetallic fenders and taillight housings for the first time.

1973½ R75/5 in Granada red

1973½ R75/5 in black

Long wheelbase (LWB) driveshaft housing. The rearward 2½" extension of the housing is visible.

Model year 1972 saw the introduction of the 4-gallon “toaster” tank with chrome side panels, so named because of its resemblance to a kitchen toaster. For the second half of the 1973 model year, BMW lengthened the rear swingarms 2½ inches, resulting in that is known now as the “long wheel base” 1973½ “LWB” models. The driveshaft of the LWB models was extended (see photo) to improve handling. For these reasons, and its 750cc power, the 1973½ R75/5 is one of the most desirable of the “slash-5” models — although some enthusiasts prefer the 1970 models because they were the first “slash-5s.”

In 1974, BMW introduced the “Slash-6” models [1], which offered numerous improvements, most notably disk front brakes, more and better instrumentation, and a five-speed transmission. The fabled “toaster” tank, however, was consigned to the dust bins of history.

[edit] Technical Data

Slash-5's new telescopic fork

R75/5 boxer engine

The R75/6 succeeded the R75/5 in 1974

All slash-5 models have air-cooled, four-cycle, opposed-twin (boxer) engines with hemispherical combustion chambers. Their engine housings are one-piece tunnels housings. The camshaft, driven by a duplex chain, runs at half engine speed and is located below the crankshaft (the reverse of the arrangement in slash-2 models). Valves are actuated by the camshaft through hardened followers, push rods, and rocker arms. The 500cc and 600cc models are equipped with Bing slide-type carburetors with 26mm throats. The R75/5 comes with 32mm Bing vacuum type carburetors. As in all BMWs to the time, the clutch is a single-disk dry clutch. The slash-5s have four-speed transmissions and come with kick-starters as well as electric starters. Final drive, of course, is by shaft running in an oil bath within the right rear swing arm and connected by universal joint to the transmission and connects on the other end to a bevel gear and ring gear. In a major change from the slash-2 models, the slash-5 models are equipped with telescopic front forks, 12-volt alternator and electrics, and standard tachometer and turn signals.

	R 50/5	R 60/5	R 75/5
Bore	67 mm	73.5 mm	82 mm
Stroke	70.6 millimeters
Displacement	498 cm³	599 cm³	749 cm³
Power	32 HP	40 HP	50 HP
@ RPMs	6,800	6,600	6,400
Torque	29 ft.lb.	36 ft.lb.	43 ft.lb.
@ RPMs	5,000	5,000	5,000
Top Speed	87 MPH	99 MPH	109 MPH
Curb Weight	452 lbs.	463 lbs.	463 lbs.
Gross Weight Rating	881 pounds
Alternator	Bosch 12V • 180 Watts
Spark Plugs	Bosch W230T30/Champion N7Y
Fuel Tank	4.7 or 6.3 gallons
Tires	3.25x19 front • 4.00x18 rear
Rims	1.85x19 front • 1.85x18 rear