The first year JAP began production of the V-twin was 1904. It was a 730cc (6HP) V-twin with a pop-up valve as the intake. These engines were used by JAP itself, as well as by Matchless, Ariel, BAT, Charter-Lea, and others. This engine was widely used in racing.

This is a restoration project currently in progress; not all parts are shown in the photo.