JAP 1912 5 HP TT Twin 738cc 2cyl ohv 3405



JAP 1912 5 HP “TT Twin” 738 cc V-twin JAP frame # S04027 P engine # 18712

In the years before the Second World War no less than an astounding 396 different brands of Australian motorcycles were offered to the public. Most were assembled from imported English or continental European components and some used American engines. In a few cases whole machines were made in Australia by a diverse group of resourceful, inventive and committed manufacturers, ranging from individuals to substantial manufacturing organisations.
A number of Australian assemblers have used only the name JAP on the motorcycles they built with these engines. Many of them used Sun cycle components and Druid forks. (Source: Robert Saward, A-Z of Australian-made motorcycles 1893-1942.)
JAP built its first OHV V-twin already in 1906 and by the nineteen teens it was regarded as the ultimate power source for sporty motorcyclists. The 5 HP was introduced in 1909 and got the “TT Twin” designation after Harry Collier won the TT with his Matchless-JAP that year. The engine had bore x stroke dimensions of 85 x 65 mm and a cubic capacity of 738 cc. A 988 cc OHV engine was also available at the time, but the 1909 TT regulations had set a 750 cc capacity limit to the twins. These competed in the same class with singles that had a maximum capacity of 500 cc. To us this would appear unfair, but at the time it was considered that multis were much less reliable than singles.
To make practical use of the considerable power of the twin a Millennium Fitall 2-Speed Gear & Free Engine device is provided. The advantage of this fitment was that it could be easily fixed to a machine’s output shaft without structural alteration. Proprietary parts are quality items such as Bosch magneto, Brooks B104 sprung saddle, and Brown & Barlow carb. The rear stopper is a substantial band brake and accessories fitted are Powell & Hanmer bulb horn and Miller acetylene lights. This mighty veteran is an older restoration in good mechanical condition.