Small Engines (Lawn Mowers, etc.): Tecumseh Charging System, charging system, dc voltage

Question
I have a 6 hp tecumseh motor I am using on a minibike.  I want to power a 12 volt headlight.  The motor has an output plug with four wires in it.  Red, yellow, white(shielded from coil, and a ground.  Between the sheilded wire and the yellow wire I have 10 volts AC.  how can I convert this to DC voltage.

Answer
all you need is are two diodes to make it dc but the light bulb doesnt matter if its dc or ac it will work on either the only reason to convert it to dc is if you need a battery or starter for it,and if you put diodes inline it will drop the voltage 1.4 volts further