Originally Posted by Bikaholic51
this looks like a winner for my Toaster.
I have a /5 as well as a GS like Sanjoh used for his first test install of the H4 bulb. Using the MaxBMW on-line parts fiche,the bulb for the R100GS is shown as an H4 bulb (part # 63 12 1 354 619 for $15.26). The /5 headlamp diagram shows a different appearing bulb (not H4 type) and has a different part number (07 11 9 978 396 for $9.47). Thus, it appears that the /5 may not be quite as simple a bulb swap out as for the /6, /7, and later airheads.