[SpudRider]

The H4 bulb won't melt the plastic housing. The glass lens is huge, and dissipates a lot of heat. Also, the wind cools the headlight as you ride. Most people don't run the headlight for long periods of time while the bike is stationary. Finally, if you think heat will cause damage, just drill a few holes in the back of the headlight housing. Most headlights are completely open in the rear; the connections won't be damaged by a little dust or moisture.