This very mean machine comes courtesy of Bonhams Las Vegas Motorcycle Sale this month, which we promised to keep you abreast of.

Behold the beauteous 1939 BMW RS 255.

The “RS” stands for rennsport, or race sport, and this model boasts a genuine, documented supercharged 1939 engine mounted in an authentic 1951 frame.

“The power characteristics are very deceptive,” notes legendary racer John Surtees, who owns a nearly identical version of the famously successful bike.

“This is a real racing machine…”