M-52S

In the early 1950s, the Central Design Bureau for production of motorcycles (Serpukhov, the Moscow Region) got an assignment for research work to create two types of road bikes with 500-cc flat engines that should be unified with mass produced M-72 machines. Two motorworks (Irbit and Kiev), manufacturing M-72 motorcycles, were subcontracted for this task. It was decided that Irbit Motorworks would start manufacturing of 500-cc bikes (the machine unified with M-72) and Kiev Motorworks would handle the manufacturing of a brand new model.

Irbit Motorworks built the first test M-52 in 1954. Its engine was designed by the Central Design Bureau. Let’s take a look at its official report, “Engine is based on the M-72 motor for maximum compatibility of spare parts; a mass produced crankcase is used, which had some minor modifications and was made at the last production stages. Diameters of the crankshaft necks and piston pins, piston rollers and separators are all unified with corresponding parts used in the M-72. A valve train is almost identical to the one used in BMW R-51/3; additionally, it has some technological advantages. Aluminium-cast cylinders have cast-iron liners…”.

Manufacturing of M-52S, a road racing model, was started in 1957. This machine had the M-77 chassis; the front fork was equipped with the M-52 wheel axle displaced forward. The engine was an upgraded mass-produced M-52 engine. As for the speed performance, the bike was equal to the legendary BMW R37 that considered one of the best motorcycles during the 1930s and after WWII.

The M-52S engine had a unique valve cover with three longitudinal stringers. By using the compression ratio 9.0 and twin carburetor configuration, the engine capacity increased to 35 hp at 6,200 rpm, which speeded the machine up to 160 km/h. In addition, a high octane fuel had an impact on speed.

From 1957 till 1961, only 20 machines were manufactured, and each M-52S motorcycle was assembled by hand.