MAS

MAS was an Italian motorcycle manufacturer associated with Milan and founded by constructor Alberico Seiling. The name was derived from the Italian phrase “Motocicli Alberico Seiling,” identifying the enterprise with its founder and its motorcycle-producing activity. Seiling developed motorcycles during the early 1920s and began commercial production in 1922. The company’s early range included a 173 cc single-cylinder overhead-valve motorcycle fitted with an external flywheel. This model became one of the manufacturer’s better-known products and helped establish MAS commercially. The company also built a larger 498 cc single-cylinder overhead-valve motorcycle. From 1928, MAS expanded its engineering approach with a 498 cc twin-cylinder machine, broadening its range beyond single-cylinder motorcycles. MAS was notable not only for conventional motorcycle development but also for experimentation with engine design. In 1937 it introduced an unusual overhead-valve layout using a specially designed cylinder head and a vertically mounted camshaft. The valves were positioned horizontally in a separate chamber above the combustion chamber, while the fuel mixture was premixed in that chamber. By keeping the valves outside the main combustion chamber, the design allowed a compression ratio of 15:1, an exceptionally ambitious figure for its period. Despite its technical originality, the design did not achieve commercial success. A major ownership change occurred in 1938, when Seiling sold the MAS business to the Guidetti brothers. The transaction marked the end of Seiling’s direct control of the MAS operation, although he continued working in motorcycle manufacturing under his own name. He subsequently operated through Seiling: A. Scoppio S.A. and in 1939 secured financing to establish another motorcycle company, Altea. Altea produced a 198 cc single-cylinder overhead-valve motorcycle, but the business ended in 1941 as the Second World War disrupted industrial activity across Europe. MAS continued as a motorcycle manufacturer until 1956. The available reference material does not document a detailed model-by-model history for the post-1938 period, nor does it identify the precise circumstances of the company’s final closure. In historical terms, MAS is best understood as a smaller Italian motorcycle marque whose significance rests on its early commercial motorcycles, its progression from single-cylinder to twin-cylinder designs, and its technically distinctive but unsuccessful 1937 engine experiment.

Alberico Seiling was an Italian motorcycle constructor who developed motorcycles between 1920 and 1922. In 1922 he began commercial production under the MAS name, an acronym connected with “Motocicli Alberico Seiling.” The company operated from Milan and initially concentrated on relatively compact motorcycles using overhead-valve engines. One of MAS’s early commercially successful designs was a 173 cc single-cylinder overhead-valve motorcycle with an external flywheel. The manufacturer also offered a larger 498 cc single-cylinder overhead-valve model. In 1928 it added a 498 cc twin-cylinder motorcycle, giving the marque a broader technical and product range. MAS continued to develop unusual engine solutions. In 1937 it presented an OLHV design using a special cylinder head, a vertically arranged camshaft, and horizontally placed valves located in a separate chamber above the combustion chamber. The arrangement enabled a high 15:1 compression ratio by removing the valves from the principal combustion space. Although technically distinctive, the engine did not prove successful in the market. In 1938 Seiling sold the MAS business to the Guidetti brothers. He remained active in motorcycle manufacturing after the sale, first producing motorcycles in his own name through Seiling: A. Scoppio S.A. and then creating Altea after obtaining financing in 1939. Altea built a 198 cc single-cylinder overhead-valve motorcycle, but wartime conditions brought the business to an end in 1941. MAS itself remained in operation until 1956. The available reference does not provide a complete account of its later ownership, model range, production volumes, or closure. Its documented historical importance therefore centers on its interwar Italian motorcycle production and its experimentation with advanced valve and combustion-chamber layouts.

• 1956

  Motorcycle production ends

  [1]MAS (Milan)en.wikipedia.org

  The documented operating period of MAS ended after approximately three and a half decades of motorcycle manufacturing.

• 1938

  Business sold to the Guidetti brothers

  [1]MAS (Milan)en.wikipedia.org

  Alberico Seiling sold the MAS business to the Guidetti brothers.

• 1937

  Experimental OLHV engine appears

  [1]MAS (Milan)en.wikipedia.org

  MAS introduced an unconventional engine with a vertically mounted camshaft, horizontally positioned valves in a separate chamber, and a 15:1 compression ratio. The design was not commercially successful.

• 1928

  498 cc twin-cylinder model introduced

  [1]MAS (Milan)en.wikipedia.org

  MAS expanded its range with a 498 cc twin-cylinder motorcycle, following its earlier single-cylinder models.

• 1922

  Commercial production begins

  [1]MAS (Milan)en.wikipedia.org

  Seiling started commercial motorcycle production under the MAS name.

• 1920

  Seiling begins motorcycle development

  [1]MAS (Milan)en.wikipedia.org

  Alberico Seiling began developing motorcycles, establishing the engineering work that led to the MAS manufacturing business.

A historic Italian motorcycle marque focused on small- and medium-displacement motorcycles, with an engineering profile that included both practical overhead-valve models and ambitious experimental engine configurations.

• Motorcycle

  173 cc OHV motorcycle

  A single-cylinder, 173 cc motorcycle using overhead-valve technology and an external flywheel. It was among MAS’s early commercial products and is described as particularly popular, making it an important model in the company’s initial market development.

• Motorcycle

  498 cc single-cylinder OHV motorcycle

  A larger single-cylinder motorcycle powered by a 498 cc overhead-valve engine. The model represented MAS’s move into a higher-displacement class than its early 173 cc machine and formed part of the company’s conventional production range.

• Motorcycle · 1928

  498 cc twin-cylinder motorcycle

  Introduced from 1928, this motorcycle used a 498 cc twin-cylinder engine. It broadened the MAS range and demonstrated the company’s interest in more complex engine configurations beyond its single-cylinder models.

• Experimental motorcycle · 1937

  1937 OLHV motorcycle

  An experimental 1937 motorcycle featuring a special cylinder head, a vertically mounted camshaft, and valves placed horizontally in a separate chamber above the combustion chamber. The arrangement enabled a very high 15:1 compression ratio for its era, but the design did not achieve commercial success.

• 1938

  Sale of the MAS businessM&A

  Background

  After nearly two decades of developing and producing motorcycles, Alberico Seiling transferred ownership of the MAS business.

  Action taken

  Seiling sold MAS to the Guidetti brothers.

  Aftermath

  Seiling continued motorcycle activity separately, while MAS operated under the new ownership until 1956.

  Source

• 1937

  Launch of the experimental OLHV designProduct launch

  Background

  MAS sought a technically advanced engine layout that could achieve unusually high compression by separating the valves from the main combustion chamber.

  Action taken

  The company introduced a motorcycle using a special cylinder head, vertically mounted camshaft, and a separate chamber containing horizontally arranged valves.

  Aftermath

  The design permitted a 15:1 compression ratio but was not commercially successful.

  Source

1. 1MAS (Milan)en.wikipedia.org