I believe the start button presses 2 terminals together. I think the old days of pressing one terminal to ground were widely considered obsolete in the 70's.
I know cos I have made and sold powdercoated bars for a 90's bike - a GS500 and never had an issue, so much so I never even thought about it till now, and I have seen the old style where they hit ground with the terminal.
You cant just scrape off the powdercoat @ the switch if it will be needed to have ground.
You have to scrape off the powder @ the triple clamp.
You also have to wire across the handle bar to ground, cos the rubber mount implies its not electrically contacting ... its contacting only via rubber.
Cool.
Srinath.