The story
In 1955 Wytwórnia Sprzętu Komunikacyjnego was asked to produce the 125 cc WFM M06 motorcycles as WFM were unable to meet market demands. Except for the tank badge the WSK and WFM models were identical. The WSK engineers started work on an improved model. The new machine had a new engine, the S-017, a new frame made of welded from closed rectangular sections and telescopic forks. This went into production in 1959 as the M06Z and a lower specification model, the M06L was also introduced. Derivatives of this model continued to be produced until motorcycle production ceased in 1985.
A 150 cc motorcycle was produced in 1960 by fitting a WFM S06 engine in the M06Z. The model, 150Z, was only produced that year.
In 1972 a 175 cc model was introduced, the M21 W2. Derivatives of this model were produced until the factory closed.
The factory was closed in October 1985, by which time around 2,000,000 motorcycles has been produced, 1,700,000 of which were in the 125 cc class.
From Wikipedia’s article on WSK (motorcycle), shared under CC BY-SA 4.0.4