The other day I was trying to see if my break lights worked using a 12v supply not even thinking that the moped 1977 Garelli Gran sport is a 6v system. I blew the light bulb and apparently something else. When I press the break leaver it activates the swtich and turns the engine off, now I have no spark after unhooking the switches and I was wondering what could have caused this problem. I was messing with the spark plug wire trying to figure out how to make the boot stay on better but I do not belive the coil is even putting out any electric because I was getting depsterate and just decided to put my hand on the main wire and didnt feel a thing. I need some help please.
The short explination: you need to replace your bulb, if this does not work, trace the break light wire back to a black plastic thing to see if that is melted (leaving an open circut probably).
The long explination:
ok, i attached a schematic for a garelli (it might not be exactly the same, but it is probably very close) and you can see that the break light system actually acts as a ground for the magneto. When the break switches are closed (no breaks) the ground travels through both switches then to ground so its all fine and dandy and no light is emitted from the taillight because it has a higher resistance than the straight ground through the two break switches, but when one of the break switches is open (breaks are put on) the electricity must go through the light bulb in order to ground the magneto, so the path of least resistance is now through the light bulb, thus the break lights normally illumenate. In short, you probably need to have a break light that isnt burnt out in the socket or you will kill the engine when the breaks are put on. If this does not fix your problem, then my guess is that you have melted the little plastic box that all the wires go into (mine looks like a thin black lego, probalby the same as yours) and there is now no contact between the break circut and the rest of teh bike. If your break lights come on right before the engine dies, then im full of shit and you can ignore me, but i am guessing that only the running lights will work.