L.A.B. said:
Some Harley Davidsons (Sportsters?) use a similar but more powerful (4 field coil) version of the Prestolite electric starter as fitted to the 850 Mk3, and it is possible to uprate the Norton starter using the H-D Prestolite field coils and brush plate, but due to differences in armatures and drive end caps the H-D Prestolite isn't a direct replacement for the Norton starter.