One thing I've discovered pretty recently: on the K4 and later 750, the rocker-style START switch is rated for 5 amps.
A typical halogen headlight on HI draws all of this, and this current passes through the START rocker when the button is not pressed (it's a toggle switch that disconnects the headlight while the starter is engaged). Over time, a halogen headlight will spell the destruction of the START switch by warping (melting) the plastic housing on the switch itself, and they are not replaceable items.
So, I just came up with an idea last month, now becoming a "kit", where a relay is added inside the headlight that follows the START button. I'll be adding it into an F2 that I'm refurbishing for someone. This carries the headlight current through it instead of the switch, so the switch can ride on...this function would be especially important if someone installs an HID headlight: their startup current can reach 11 amps, which will quickly damage the START switch on the later bikes. A relay is certainly in order for those headlights, even though their running current is only in the 3 amp range.
For those of you who want to roll your own: get a 5-terminal automotive relay (the little 1" cube variety, of which I now have 50 in a big box..) and connect the START wire from the right switch to the coil (and GREEN to the other side). Connect the STARTwire from the switch to the NO contact and the headlight power wire (BLACK/WHITE or BLACK/YELLOW on different models) that goes to the left HI/LO switch to the NC contact. This will keep all functions the same, but will deliver all the grunt work through a $7 relay instead of a $90 switch.