Beaver53,
Generally speaking, a 6 volt switch should be rated for twice the current as a 12 volt switch. They probably aren't dialed in this way, but from the standpoint of Ohms Law, the math says 'twice the voltage..half the current'.
Running the 12 volt motor at a comfortable speed might require the switch to be running like a little toaster most of the time, but it should handle it...the main concern would be having one of the grand kids grabbing it..OUCH!
Just remember the battery cable thing. Modern 12 volt cables are the size of a straw. Old fashioned 6 volt cables are the size of a elephants trunk. With only half the 'pressure' they have to be twice as big to get all those little 'amperes' shoved through to Mr. Starter.
Stuart
