When starting to develop Junak's construction, the designers faced great difficulties resulting from the need to take into account a wide range of operating conditions for a motorcycle of this class, heavy road conditions, and production capabilities. Poland had not produced a motorcycle of this class before, other than those from the pre-war PZInż. plants which had ceased development when preparing for the production of an overhead valve Sokół 500cm3 engine.
In October 1951, the basic tasks of the future motorcycle were established. It was to be used for by the police (known as the civilian militia), commuting and touring.
The author of this piece was of the opinion that when designing motorcycle components, although they were ordered to build a 350 cm3 class motorcycle, they "quietly" designed as if they were building a "500" (these are assumptions, unsupported by specific evidence). All the main parameters such as power, engine design, number of gears, even the way of transferring power from the engine to the clutch were defined already in the first phase of the project. When constructing the Junak the world's best examples were studied, which is why it is visually similar to British machines - but it is not a copy.
It is distinguished from English motorcycles by the gearbox being housed in the engine crankcase. The British four-stroke machines have of three separate elements: the engine, the clutch and the gearbox. The work on the motorcycle itself began in the design office of the automotive industry in Warsaw in 1952.
The creators of this machine were Eng. Jan Ignatowicz (project coordinator), Eng. Krzysztof Wójcicki (engine) and Eng., Stefan Poraziński (chassis). The prototype, which was named Junak, built with the help of the Warsaw Motorbike Factory, was presented at the exhibition of the decade in Wrocław in August 1954. After long tests in various field conditions, several flaws had been discovered and rectified including the cracking of frames on some early machines.
The chassis, after correcting the angle of inclination of the front shock absorbers (the rake and trail), showed very good handling properties. The rear shock absorbers were also described as a very good design, they were said to work better than in the Royal Enfield 350.
In those years, the youngster was a modern motorcycle. It was compared with fresh English constructions such as the BSA 350 or the aforementioned Enfield. Initially, Junak was to be equipped with deep front guards attached to the fork clamp, but this changed to a much smaller guard mounted just above the wheel. The mechanical gearshift indicator, which was located on the left side of the engine together with the gearshift lever, was also abandoned. There were problems with localizing the production of Junak.
Finally, it was decided that the engine would be manufactured at Wytwórnia Sprzętu Mechaniczne in Łódź, while the remaining units and assembly at Szczecinskie Zakłady Wyrobów Metalowych, which later changed its name to Szczecin Fabryka Motocykli. In 1956, 30 units were built as trial series, and the actual production began in 1957. Overhead valve engine, 17 hp (the first machines left the factory gates with engines tuned to 15 hp, although it was possible to increase their power to 17 hp) together with a four-speed gearbox, ensured good vehicle performance.
A stable frame with a closed structure turned out to be insufficiently durable, it cracked in the area of the headstock, this defect was removed in the new type of frames by strengthening the joint, adding sheet inserts and changing the frame welding technology. Suspension of both wheels on spring elements, with oil damping, guaranteed proper handling of the motorcycle in all road conditions. The five-year process of preparing for production did not cause any significant aging of the motorcycle design, it underwent transformations during that time.
For some time there was a discussion in the press about the under-utilization of production capacity and the further fate of the motorcycle factory in Szczecin.
The plan for 1963 envisaged, for example, the production of 20,000 Junaks, but it was not implemented because the market demand for a 350cc class motorcycle was much lower than anticipated. The halted production and uncertainty as to the further fate of the plant aroused many reservations and fears among the staff. That situation changed, and the new tasks for SFM, developed by the union of the automotive industry, envisage not only the use of the existing production capacity of the plant, but also the further development of the plant.
However, there would be changes to the plan. These included: production of 350cc motorcycles to be severely reduced. In 1964, only 10,000 would leave the factory. However, in the event of a further reduction in sales for these motorcycles, their production would be discontinued after exceeding the break-even point. The calculations showed that the annual production of 10,000 units per year is still profitable.
In 1964, SFM took over the specialist production of drive shafts and steering mechanisms for the entire automotive industry. The development of the metallurgical department of SFM based in Stargard acceleratee. For the implementation of these tasks, SFM took over the necessary machinery from FSC Starachowice and FSO Żerań. In the future, the plant recieved increased investment.
Such determination of SFM production of additional production capacity in the basic automotive plants - FSO Żerań and FSC Starachowice. The light and non-ferrous metal foundry in Stargard adopted part of the production tasks from the mechanical plants. Thanks to this, Nowotki will be able to increase the supply of hulls for S-53 diesel engines to FSC Starachowice. In the future, SFM will also launch the production of sintered powders.
As a result, SFM will be burdened with new, particularly labour-intensive tasks and the value of the manufactured products will be maintained! Within 500 miles and will correspond to the production of 20,000 Junak motorcycles.
N.B. If some of the above leaves you mystified, trust me, you're not alone. Ed.
Source: Junak.net Archive