Can't speak to the vapor.
Is 12 VDC what you're measuring at the battery? Is the bike running? What are the RPMs when you measure? You say the voltage 'dropped', so presumably there's a charging and/or a battery issue...
My voltage (read at the instrument cluster) is 12.2-12.4 with the key on, not running. It falls to 10.something-or-so during start-up, then once the engine's running climbs steadily to 13.7-13.9 VDC at idle (1K RPM). Going down the road at 3k-4k RPMs it reads 14.0-14.1 VDC. I keep my battery on a Tender when not riding, and the battery is fairly fresh (couple months old).
Alan