| Here in the USA, Ducati 999 have H3 bulbs in both the high and low beam projector-type light units. So, like the H3 low beams in the earlier superbike models they can’t be replaced with a HID element without getting an unacceptable light pattern. The H3 bulb has a transverse (side-to-side) filament but earlier HIDs had only a longitudinal (front-to-back) element suitable only for H1 low beam reflector-type lights.
H4 bulbs have two longitudinal filaments located at different distances from the base so they have different focal plane distances. The light optics (usually reflector-type) are then designed around the two filament positions to get the correct light pattern at both high and low beam positions.
So the UK 999 lights are different than the ones sent over here? This surprises me since projector-type lights used on the 999 are usually designed around a single filament and used as the high beam or low beam only. Certainly the right-left dip direction is different here but that doesn’t account for the difference.
Note: A quick search finds only HB3 lights listed for the French, German, and Italian 999s. Double-check your manual.  |