Installing a heavy-duty headlight guard like the Big Cee unit often generates concern over its effect on the headlight pattern. I attempted to examine this by photographing the headlight pattern on high and low beam both with and without the guard installed, so a direct comparison could be made. In the following pictures, the headlight is shining on a vertical surface, about 10' away from the bike. Unfortunately, I forgot to pick and set a fixed exposure time for the photos, and left the camera on auto-exposure. So, these photos will not show any average degredation in light output. However, they do show that the guard doesn't affect the light pattern. I hope to take a new set of photos soon, with a fixed exposure time. I would also like to take pictures of the beam layout on the ground, but this would be a bit more difficult to do effectively. These pictures were taken with a stock 55/60W H4 halogen bulb.
Low-beam comparison. Upper picture is plain headlight, lower picture is with guard installed.
High-beam comparison. Upper picture is plain headlight, lower picture is with guard installed.
As shown in the photos, the headlight pattern is slightly more diffuse with the headlight guard in place, but there are no dark areas. You will notice some light deflected to the sides of the motorcycle, in the pattern of the expanded metal. There will also be light reflected back into the cowling, around the backing plate. To avoid distraction at night, it may be necessary to place tape over the gap (or build and install the mini sport dashboard).