The Complete Illustrated Encyclopedia of the World's Motorcycles (Copyright 1977) has the following two pages dedicated to Puch:
PUCH / Austria 1903
Austria's oldest motorcycle factory. During the early years, the company manufactured motorcycles with their own 2.75 hp, 3.5 hp, and 4 hp single-cylinder and 4 hp and 6hp V-twin engines. There was also a 6 hp flat-twin, built during WWI in limited numbers. Double-piston two-strokes dominated the production programme for some years after 1923; designed by Giovanni Marcellino, they appeared with 122cc, 173cc, 198cc, 248cc, , 348cc, and 496cc capacity. The 348cc single was built only in 1938, mainly for the army. The only four-strokes made by Puch between the wars were 490cc JAP-engined sv singles in 1928 and in 1936-1938 the 792cc transverse-mounted sv flat-fours, also mainly built for the army. Smooth-running 496cc vertical twins with the four-piston two-stroke engines were made since 1931 in various shapes, among them the models Z, N, V and VL. In this case the second cylinder was standing behind the first. In 1938 a 60cc bicycle engine called Styriette came into production. Most famous of all Puch two-strokes at that period were the 248cc singles, especially the very sporting model S4, built from 1934 to 1938 with a 14.5 bhp engine. Puch built during the years racing twostrokes, including in 1924 the Monza works machines with two 122cc cylinders on a common crankcase, and from 1929 onwards watercooled 248cc double piston singles with a charging cylinder in the crankcase. These very fast machines won the German Grand Prix in 1931 as well as many other big events. Among leading Puch riders were Nikodem, Obruba, Wetzka, Medinger, Hšbel, Cmyral, Toricelli, Hunger, Nowak, Sandler, Novotny, Suchanek, Runtsch, Karner, Kiss, Lukawetz, Puch Jun., Zick, Lehmann, SchlŸpbach, Faraglia and others.
After 1945, the range of models included 123cc two-strokes with single piston engines and pressed steel frames, but many 248cc double-piston models were kept in production and now got pressed steel frames too. Improved versions were still in production in the early 1970s, such as th SGS with 2mm X 45mm bore, 78mm stroke and 16.5 bhp at 5800 rpm. Still, main production concentrated around 49cc mopeds, mofas, motorcycles and 123cc and 173cc machines with new, modern, single-cylinder and single-piston power units. Among them are various trials and moto-cross machines which gained success with riders such as Harry Everts, Walter Luft, Walter Leitgeb, Hans Sommerauer and others. Among present Puch motorcycles are the M50 Jet and M50 Monza GSL with 6.25 bhp 49cc engines, the MC50 Super with 49cc and 11.2 bhp at 11,000 rpm (moto-cross model). 123cc and 173cc versions with 23 bhp and 28 bhp and also a 246cc moto-cross Replica with 43.5 bhp at 8500 rpm.
There are eleven pictures of motorcycles shown on the two pages. The one which most resembles yours is captioned, "246cc Puch (TS double-piston Model 'SGS') 1966"
Good luck with the project. Please keep us up to date as you progress.
Al