T145 1972 BSA B50 MX In the mid-20th century, BSA was well known for building powerful, single-cylinder, 500cc motorcycles, such as the fabled Gold Star. By the early 1970s, BSA was in financial trouble, but the company still proved to be competitive in the large-displacement, single-cylinder motorcycle market. An example of just how competitive it could be is this 1972 B50 MX, a machine that was owned and raced by Casper, Wyoming, motorcycle dealer and legend Tim Oler. BSA actually offered three variants of the oil-in-frame B50, which was built from 1971-1973. There was the Gold Star 500 SS with steel gas tank, full lights and instrumentation, the Victor 500 Trail (actually only built in 1971 and 1972) with its alloy gas tank, lights and speedometer, and the near-naked Victor 500 MX scrambler. The models featured the same all-alloy, air-cooled, four-stroke, single- cylinder engine with unit-construction 4-speed transmission. With its 84mm x 90mm bore and stroke, the single measured in at 499cc and had a 10:1 compression ratio. The Gold Star and Trail singles made 28 lb-ft of torque, while the MX, with a 32mm Amal Concentric carburetor versus the 30mm of the other models, was rated for 35 lb-ft, all at 5,000 RPM. On the MX, there was 7.5 inches of ground clearance, and the bike weighed just 260 pounds dry. Pouring gasoline into the 1.25-gallon, polished alloy gas tank with Hi-Violet stripes wouldn’t have added too many extra pounds. Slowing the bike down were BSA’s conical drum brakes, a 6-inch up front and a 7-inch out back. Wheels, 20-inch front and 18-inch rear, were shod with aggressive knobby tires, and the 1972 B50 MX offered here is likewise equipped. It was built to compete and features modifications to the cylinder-barrel fins, while a Mikuni carburetor is on the intake manifold. Aluminum panels have been fabricated to replace the plastic side number plates, and the fenders are aftermarket plastic.
