HI, yes a 6 volt motor that is hooked up to 12 volts would run at 2x its normal speed , the only way to really find out if its 6 volt or 12 volt is to take a ohm reading the only problem is You have to have one that You know is 6 or 12 if You want I just took out My 6 volt heater motor today I can OHM test it tommorow and give You the reading , Pete PS. You got a OHM meter ?
