Was helping a guy sort out some electrical issues on a K75 he's recently brought back to life. He installed an aftermarket headlight on the forks. I get a fair amount of people asking me for potential "naked" bike headlight solutions so I asked him how he did it and where he got the parts.
Here's the finished product:
(http://i278.photobucket.com/albums/kk91/electro_handyman/Bike%20Tech/naked_headlight_installed.jpg)
Here's the "bucket" he used. EMGO product 66-65010.
(http://i278.photobucket.com/albums/kk91/electro_handyman/Bike%20Tech/emgo_66-65010.jpg)
Here's the sealed beam 7" headlight he used. It's a Bosch 7022.
(http://i278.photobucket.com/albums/kk91/electro_handyman/Bike%20Tech/headlight_lens_39-7022.jpg)
Here's the brackets. EMGO product 66-3583.
(http://i278.photobucket.com/albums/kk91/electro_handyman/Bike%20Tech/brackets_66-35830.jpg)
All are available from Dime City Cycles (http://www.dimecitycycles.com)
Bucket: $55
Headlight: $38
Brackets: $35
TOTAL: $128 plus shipping and some bolts from your local hardware store.
Note that 4V K bikes use slightly larger diameter forks so I'm not sure if this setup will work on a 4V K bike.