The Pionyr (or Pioneer) was introduced in 1955 as model 550, which became known as the “tree stump” because of the shape of the saddle. This wasn’t classed as a moped but was a lightweight motorcycle and was designed by Jawa but made by the Povazske Strojarne factory in Western Slovakia, later to go on to produce the Babetta models.  See the two articles right, for more on the 550. In 1958 a new model, the 555 was introduced with a number of improvements, see the 1958 CMR article below-right for more details.
As some of these adverts show, the Pionyr was sold along side the Jawetta. The Pionyr, which didn’t have pedals, was marketed as a lightweight motorcycle.  The Jawetta, with pedals, was a moped being more suitable for “women and juveniles” - their words, not mine.  Although both had similar 49.8cc engines, the Pionyr had 2.2HP with a 3 speed gear box against the Jawetta’s 1.5HP & 2 speed box.

An article about the model 550 from Czech Motor Review 11/1956. 

From Czech Motor Review 8/1989 looking back at the history of the model.

From Czech Motor Review 1/1958 introducing the 555 model.

Two adverts from Finland, from 1960.

Two 555 items ...

from Czech Motor Review

A 1959 letter to dealers from the UK importer to.

& from a UK magazine

A 1959 advert from the USA.

Two versions of a similar 1959 Pionyr advert.

Some Pionyr photos from magazines.

In 2006 a company called Motoscoot started producing a recreation of the model 555. Here is a couple of posters for the NEW Pionyr model and an article from Torque giving more information.

A couple of Czech magazine covers.