Delta motorcycles have been in production since 1997.
The unit is sold as the Dart and is a modern clip-on that can be fitted to the bottom bracket of a standard bicycle, which requires one new pedal crank to clear it. The fuel tank is clipped to the frame. The 35cc two-stroke unit has a horizontal cylinder, electronic ignition and an automatic clutch. Drive is by friction to the rear tyre giving fuel consumption of about 200mpg or 1.4 litres per 100km.
Sources of Information
The British Motorcycle Directory - Over 1,100 Marques from 1888 - by Roy Bacon and Ken Hallworth. Pub: The Crowood Press 2004 ISBN 1 86126 674 X