Easiest way to rect/reg mopeds in my experience is buy a cheap 4 pin scooter regulator rectifier. Costs like $10 or less.
AC from stator in, 12vdc out (max up to 14v) out to battery and dc shit. No bulb blowing, no probs. Perfect way to run LEDs without issues.
You can even regulate the AC for the lights by tying that line into the light pin on the reg. It'll bring it down to 12-14vac.
This is only if your stator has enough juice. My 6v hobbit puts out way too much voltage so it works perfect. 6v Mobys work too... (edited)