Historic Motorcycle Brands
Sunbeam
The ‘Sunbeam’ name was registered by John Marston in 1888 for his bicycle manufacturing business. Sunbeam motor car manufacture began in 1901 and Sunbeam motorcycles were not made until 1912. There were three distinct generations of Sunbeam bikes.
From 1903 John Marston Limited had made some early experiments in adding engines to bicycles but they were unsuccessful and, tragically, a man was killed. That accident created an aversion to motorcycles and John Marston’s efforts were diverted to cars that were built from 1902.
However, Sunbeam suffered a slump in car sales and, from 1912 onwards, Marston was pushed into making motorcycles, for which there was a large and increasing market.
By 1912, when John Marston decided to commence production, one of the major technical disincentives to ownership – the lack of a clutch – had been overcome. Sunbeam also missed the era of belt-driven transmission.
From the start Sunbeam employed a chain drive enclosed in its famous ‘Little Oil Bath’, derived from its tried and tested bicycle technology.
Following in the tradition of Sunbeam’s bicycles, the motorcycles were of high-quality, usually powered by single-cylinder engines and known as ‘Gentlemen’s Machines’.
They developed relatively low power, but a hallmark of all Marston Sunbeams was superb quality and all were finished in black, with gold-leaf pin-striping.
Many John Marston Sunbeam motorcycle models were produced. The first was a 2 3/4hp 350cc single, after Marston commissioned Harry Stevens, of AJS Motor Cycles, to design this first Sunbeam motorcycle engine.
This was followed in 1913 by a proprietary V-twin machine with a 6hp JAP engine of 770cc capacity and this model remained in production into the early part of the First World War in 1915.
John Greenwood designed a 499cc, 3½hp model for 1914. A sporting TT version won the Manufacturers’ Award at the 1914 TT and again in 1920. A modified version became a ‘General Service’ machine for the War Department during the First World War.
After the First World War John Marston Limited was sold to a consortium. In 1919, the consortium became part of Nobel Industries Limited.
A JAP-engined machine was reintroduced towards the end of the War. This 8hp model had a larger 996cc engine and continued in production until 1923. It was designed as a heavy-weight machine to pull a sidecar.
Marston’s prototype, long-stroke, side-valve engine of 492cc had an unusual 77mm bore and 105.5 mm stroke. It was tried under fire at the 1921 French Grand Prix and went into production the following year, winning the Senior TT. It was the last side-valve-engined motorcycle to win a TT.
The Longstroke remained in production for the life of the company and was known as the Model 6 after 1924.
A bored-out engine displaced 596cc and was developed for sidecar work. This model became the Model 7 after 1924 and the ‘600cc Lion’ in later years.
In the mid-1920s, the Model 5 employed the original ‘square stroke’ Standard engine with the Longstroke’s sporting frame. That model number transferred to the touring version of the Longstroke in 1926 and both models were replaced by the Lion in 1931.
The 3½hp model continued in production until 1926 and became the ‘Model 3’ in 1924, when a new model numbering system was introduced: Sunbeam Models 1 through 11. Other higher-numbered models were produced in later years.
In 1924, Sunbeam introduced new overhead-valve models 8, 9, 10 and 11, with the valves controlled by triple return springs. The Model 8 had a 350cc, 23/4hp engine, with an EIC magneto and AMAC carburettor. Engine lubrication was by a Sunbeam-patented, automatic dry-sump system.
It also had, for the first time on a Sunbeam, internal-expanding brakes, front and rear. The racing version had a straight top tube and a smaller fuel tank.
In 1927 Nobel Industries amalgamated with Brunner Mond Ltd to form Imperial Chemical Industries (ICI). Within this huge organisation, motorcycle manufacturing played a small part.
The Model 8 disappeared in 1928, then re-appeared in 1929, sporting a saddle tank and a lower riding position. The 1924 Model 9 was powered by a 31/2hp 493cc OHV single and received major upgrades in 1929: three-ball-bearing crankshaft; dry-sump lubrication; enclosed pushrods and a saddle tank.
The Model 9 was progressively upgraded until 1936 and the 600cc, Model 9A that had arrived in 1932 continued, with upgrades, until 1940.
Another product line started in 1931, with marine outboard engines first marketed as Marston Seagull, later famously known as British Seagull.
In 1937 the Sunbeam motorcycle trademark was sold to Associated Motor Cycles Ltd (AMC), which continued to make Sunbeam bicycles and motorcycles until 1939. AMC’s core business was the manufacture of Matchless and AJS motorcycles.
In 1938, AMC introduced a completely new range of four Sunbeam models, starting with the 246cc B23, up to the 598cc B28. The AMC engines were high-camshaft, OHV designs that had been developed before the takeover of Sunbeam.
The AMC Sunbeams had four-speed Burman gearboxes and Matchless front forks and all four models could be had in Standard, Sport or Competition configurations.
However, in 1943, AMC sold the Sunbeam name to BSA and Sunbeam Cycles Limited was incorporated. Sunbeams were built not at BSA’s main factory in Birmingham, but at another BSA factory in Worcestershire.
Three Sunbeam motorcycle ’S’ models were inspired by BMW motorcycles supplied to the Wehrmacht during the Second World War. They were followed by two scooter models from 1959 to 1964.
The S models were designed by Erling Poppe and manufactured from 1946 to 1956. There were three: the S7, S8 and S7 Deluxe. All three were very expensive, but with only modest performance and that resulted in few sales.
An unusual engine layout was the S7’s notable feature, with an engine and drive similar to that of a car. The engine was a longitudinally mounted, in-line, vertical OHC, 500cc, twin-cylinder, with coil ignition and wet sump lubrication. A dry clutch sent shaft drive to the rear wheel.
The in-line engine made shaft drive logical, just as flat-twin ‘boxer’ engines in BMW motorcycles used shaft drives.
Unlike BMW’s bevel gear, crown-and-pinion drive at the rear wheel, Sunbeam used worm gearing with a bronze spiral gear. It was a beautifully quiet and precise drive, but the relatively soft bronze caused rapid wear of drive components.
The original S7 was the first production variant, being produced from 1946 to 1948. In 1949, the sportier S8, with standard-sized wheels and tyres, rather than the S7’s fat ‘balloon’ tyres and with BSA-type front forks, was produced.
The S7 design was improved and then sold as the S7 Deluxe. The original S7 was available only in black, whereas the standard colours for the S8 were ‘Polychromatic Grey’ or black. The S7 Deluxe came in either ‘Mist Green’ or black.
For export, BSA supplied Sunbeams in almost any colour that BSA used. Although the early S7 was not a good seller or mechanically very sound, it is the most sought after and commands a premium over the S7 Deluxe and the S8.
When Sunbeam production came to an end, BSA sold the remaining stock of parts to Stewart Engineering and this company became the supplier of spares for post-war Sunbeam motorcycles.
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