The BMW /2 Series

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Photo by Markus Hartel
Bill Costello on his restored 1958 BMW R50.

“If you want to be happy for a day, drink. If you want to be happy for a year, marry. If you want to be happy for a lifetime, ride a BMW.” That’s the copy from a 1965 ad for the BMW flat twin, commonly referred to as the Slash 2, or /2. Built by Bayerische Motoren Werke between 1955 and 1969, the machines were either a low compression 500cc R50, low compression 600cc R60, or, as introduced in 1956, a high compression R69. In reality, only the 1960-1969 officially carried the /2 designation. But as BMW guru Jeff Dean notes on his website, many owners commonly refer to the entire series as Slash 2s.

With its low compression 494cc flat twin, the R50 could be considered the base model of the BMW twin series for 1958. The twin, widely recognized for its smooth power delivery to the rear wheel via clean shaft drive, produced 26 horsepower. The next machine in the range, the R60, a 590cc flat twin, offered only two more horsepower from the mill for a total of 28.

The R69 was considered the hot rod of the line, rated at 35 horsepower from its 590cc, 8.0:1 compression ratio flat twin. In 1960 it was replaced with the R69S model, which upped the horsepower to 42 with even higher 9.5:1 compression.

The BMW gets its “boxer” moniker from its piston arrangement, with the pistons diametrically opposed and moving apart and together at the same time — legend holds the term was coined by Adolph Hitler, who, viewing a BMW engine factory, said the moving pistons reminded him of a boxer slapping his gloves together. And although one is on a compression stroke while the other is on an exhaust stroke, this allows the engine to remain fundamentally balanced.

By the time Richard Costello purchased his 1958 BMW R50 in 1961, BMW had made a strong impression on the motorcycling fraternity.

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