Indian 1915 5 HP Model B-3 ‘Little Twin’ 684 cc IOE V-twin frame # 50654 engine # 50G547 gearbox # 1644 Indian’s first, 38.61ci (633cc) v-twin appeared in 1907 with an engine clearly derived from that of the single, though mechanical inlet valves – introduced for 1908 – were an early improvement. The twin’s rear cylinder continued to form part of the frame until 1909 when a loop frame of the type favoured by rivals Harley-Davidson was adopted. The Springfield Company’s first ‘Big Twin’ debuted t ...
Harley-Davidson 1948 Model GA Servi-Car 742 cc side valve v-twin frame # 48G16916 The Harley-Davidson Servi-Car was put on the market in the course of 1932 when Harley-Davidson was desperate to expand its product base to increase sales. Initially the new product was targeted at the automotive service industry, as Indian had done shortly before with their successful Dispatch Tow. The idea was for a garage to be able to send out one man (rather than two) to collect a customer’s car and to return w ...
Harley Davidson 1942 “U” 1209 cc side valve V-twin frame & engine # 42U2744 video: https://youtu.be/sG4m_zw15kc For 1937 the HD engineers redesigned the Big Twin range: frame and cycle parts of the newly introduced OHV ‘Knucklehead’ were used as the basis for the new 1209cc and 1303 cc models U and UH. An important new feature was the introduction (finally!) of dry sump lubrication. The “U” was the 5.0:1 low-compression type; the standard compression was 5:1. Power output of the U was 32.5 hp @ ...
BMW 1964 R 50/2 494cc transverse twin combination frame & engine # 636873 In 1955 BMW creates its R50, R60, and R69 models. These new models have a similar engine and the same shaft-drive as earlier models, but are fitted with modern swingarm rear suspension for the first time. The telescopic forks at the front of earlier models are abandoned though, in favour of the swinging or “Earles Fork” system. The cycle parts are finished in BMW’s signature black scheme set off by white pin striping. The ...
Sunbeam 1927 3½hp Model 6 ‘Longstroke’ 492 cc side valve frame # B1730 engine # J1778 video: https://youtu.be/EGi6aHZC4KU After the Great War, Sunbeams first new design was a side valve of 77mm bore and 105.5mm stroke and a cubic capacity of 492 cc. At the works it was known as the ‘Longstroke’ to differentiate it from its short-stroke 85 mm x 88 mm ( 499 cc) predecessor. The new engine made a fantastic impression at the 1921 French Grand Prix on July, 24 at the Circuit de la Sarthe near Le Mans ...
Harley-Davidson 1924 “JE” 989 cc IOE V-twin frame # 24F4203 engine # 24JE4408 video: https://youtu.be/rZXMm4cWhok 1924 is not a good year for the firm: the losses amount to almost $ 120,000 and the workforce is trimmed down from 2,500 to 1,000 employees. Sales in the USA have seriously diminished in the early twenties because of the competition of the cheap automobile. A positive thing is that export sales are still looking good. More than 6000 machines are exported oversees this year; this amou ...
Sunbeam 1932 Model 90 493 cc OHV frame # E13074 engine # NN6053 gearbox # BW1754F video: https://youtu.be/OwLfeKQ5MXQ The Model 90 first appeared in the firm’s catalogues for the 1927 season. Sunbeam had tried to develop an OHC racer but that proved to be unsuccessful: the camshaft Sunbeam that appeared in 1925 was seriously lacking in torque and power because of problems with valve timing. The much more direct ohc mechanism necessitated a totally different valve timing, of which there was very ...
BMW 1976 R75/7 745cc OHV transverse twin frame & engine # 6020431 In the early autumn of 1976 BMW’s ‘/6’ series is replaced by the ‘/7′. The R90S-style fuel tank (adopted across the range) and redesigned rocker covers are distinguishing features while at the top of the range, 980cc R100 models replace the ’90’ series. The R75 probably offers the best compromise between power and economy, turning out 50 hp @ 6,200 rpm and having a petrol consumption of around 1:20. Top speed is 180 km/h and the d ...
Sunbeam 1914 3½hp 499 cc side valve frame # 2582 engine # 2575AN At the end of the 19th and beginning of the 20th century the Wolverhampton based firm of John Marston Ltd. has already earned fame for their superb bicycles. During 1911-12 it is decided to take up motorcycle manufacture: designer John Greenwood, who has already made his mark at the JAP and Rover companies, is contracted and will be responsible for most Sunbeam designs till the mid-thirties. As a consulting engineer for the engine ...
Harley-Davidson 1933 “VLE” 1217 cc side valve v-twin frame & engine # 33VLE2610 video: https://youtu.be/Ys8BBlSQxeo Harley-Davidson’s 1930 brochure describes the new 74ci (1217 cc) machine as “standing head and shoulders above all comers, with such startling new features as a 20% more powerful motor with Ricardo removable heads, interchangeable wheels, bigger tires, drop-centre rims, lower riding position, greater road clearance, automatic increase of generator output, drop forged forks, 100% st ...
Indian 1925 Scout 600 cc side valve V-twin engine # 55Y447 The successful Scout model boasts quite a few new features for the 1925 season: removable cylinder heads, larger valves, improved clutch with greater plate area and a different type of saddle suspension to insure greater riding comfort and a lower riding position. For better engine breathing wider valve cam profiles are used. The 1925 brochure shows a power chart that claims a 20% power increase for the 1925 Scout as compared to the 1924 ...
Harley-Davidson 1930 model DL 742cc side valve V-twin frame # 123078 engine # 30DL2747 video: https://youtu.be/mAnYR4fergQ The HD company introduced the side valve concept for the V-twins for the 1929 model year when the 742cc model D was introduced. The model D is sometimes referred to as the “three cylinder Harley“, because of the remarkable vertical position of the dynamo: in a cost saving idea, the new motorcycle was designed to use the existing frame from the 350cc Model B single. This requ ...
FN 1931 M 70 C “Sahara” 346 cc side valve frame # 69284 engine # 19209 video: https://youtu.be/Yt8Nq7II0gQ At the end of 1923 FN presents a 350 cc single cylinder ohv with unit construction engine. This model, the M60, is the start of a successful new line of models in a period in which the heavy and expensive four cylinder is quickly loosing ground. Two years later a bigger 500 cc brother is brought out, the M 67. Shortly after that FN four cylinder production is finished. The ohv singles are v ...
Excelsior 1918 Series 19 998cc IOE V-twin frame # 18923 engine # 85883 video: https://youtu.be/w-L55_ON3wg 1911 was a landmark year in Excelsior’s history, for the firm was acquired by bicycle maker Ignaz Schwinn and introduced its first v-twin model that year. In 1913 a twin within the 61 ci displacement was offered with all-chain drive, while two-speed planetary transmission and a leaf-sprung, Indian-style front fork were two of the following season’s innovations. Alongside rivals Harley-David ...
Harley-Davidson 1934 “VFD” 1217 cc side valve V-twin frame # C188 engine # 34VFD1663 Video: https://youtu.be/sHnqjCt0sRY There are various new features for the 1934 model year, many being mainly cosmetic. The cylinders are modified and new tank graphics with “Flying Diamond” design are introduced. Frames and forks are now completely heat treated and the company states that this “adds full fifty per cent more strength”. The mudguards get a new shape and a new “Airflow” tail lamp is fitted. 1934 w ...
Douglas 1928ca “DT/ SW 5” 498 cc flat twin ohv racer frame # TF 257 engine # EL779 gearbox # YG1175 When speedway racing arrived in Britain in 1928, the new sport quickly caught the public’s imagination and before long many major UK manufacturers listed a dirt track model, Douglas being the first marque to establish dominance with its 500 cc DT 5 and 600 cc DT 6 overhead valve models. The company’s inline flat twins had benefited from much prior development on the Australian long tracks, but as ...
Harley-Davidson 1933 model RE 742 cc side valve V-twin combination frame # 33-1037 engine # 33RE1067 video: https://youtu.be/-3bfzcfV2TQ Introduced in 1931, the Model R series was the successor of the Model D. The latter had the generator mounted vertically, which proved a vulnerable design point. So with the new R the generator was placed horizontally in front of the engine and driven by a conventional gear drive directly from the timing gear train. Consequently, a newly designed and heavier fr ...
AJS 1912 “Model B” 2 ½ HP 315 cc side valve single frame # 636 engine # 1696 gearbox # 296 The Stevens brothers Harry, George, Joe Junior and Jack had been in motorcycle engine manufacturing for various clients since the final years of the 19th century. In the course of 1909 it was decided to start building complete motorcycles under their own name. In 1910 two models were developed and built, Model A with direct belt drive and model B with chain drive and 2-speed gearbox with cork inserted clut ...
BMW 1939ca R51 unfinished restoration 494cc ohv horizontally opposed twin frame # 512929 engine # not clearly visible In the late thirties BMWs are sold in considerable numbers, in spite of their high prices; in the UK a 1938 BMW R51 costs £123, while a Triumph Speed Twin can be had for less than £77. The make has built up an excellent reputation for quality and luxury: from 1938 on all BMWs have both front and rear springing, a feature which is at the time very uncommon for most other makes. Fr ...
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