Originally Posted by svc
You will need a rectifying circuit (very easy 4 diodes, google for a pic). Its 6volt . I wired a big halogen spotlight with built in battery to mine and ended up losing spark, make sure you add a switch to turn the charge circuit off if needed to isolate problems. I have seen the photo's on here that show the white and blue wires aren't connected and they made sense, but that was my experience.
hope this helps
A full wave rectifier ( 4 diodes) will kill your spark. Only a half wave will work, and you have to orient that single diode the correct way to enable the engine to run.