British motorcycle manufacturers - J

James	James started out as a bicycle firm in Birmingham, founded by Harry James in 1880, moving to larger premises in 1890 and going public in 1897. Their first motorcycles in 1902 used Belgian Minerva and FN engines, but they made their own engine in 1908 and their own two-stroke in 1913. They started building four-stroke singles and large V-twins in the 1930s but went back to lightweights before the war. Production continued into the 1960s, based on two-stokes, notably the 250cc Commodore and the twin Superswift. They built the first internally-expanding brakes in 1908. James took over the Baker motorcycle company in 1931 (its founder built the first Villiers engines).  About 300 Model ML (Military Lightweight, 125cc) James were used on the beaches of Normandy on D-Day. About 6,000 motorcycle were produced in WW2 for the Allies. After the war, they reverted back to Villiers engines. The company was acquired by AMC in 1951 (47?) and ceased production in 1964, disappearing when AMC folded in 1966.
JAP	Named for James (John) Alfred Prestwich, who founded his own company at age 20, in 1894. Designed his first motorcycle engine in 1901, but it wasn't produced until 1903. Made the first overhead-valve V-twin in 1906. Built a 660cc three-cylinder engine for Dennell. Val Page worked for JAP before going to Ariel. JAP patented a desmodromic valve design in 1923.Very successful after WW1 supplying engines for many manufacturers, but as more companies developed their own engines, JAP relied heavily on industrial engine sales in the 1930s. Merged with Villiers in 1957.
JD	1920-26. Clip-on engines. Another  (?) company in 1902.
JEHU	1901-10
JES	1910-24
Jesmond	1988-1907
JH	1913-15
JNU	1920-22
Joybike	1959-60. Scooter, 49 and 70cc.
Juckes	1910-26.
Juno	1911-23
Jupp	1921-24