RE: Alternator / Generator on a 50cc Gas engine.
Considering your geographical location and it's relevance to surrounding areas the information you request could have considerable long term impact in ways other than what many might be able to foresee. That which is already commercially available already is, more than what is already openly marketed might best be maintained in obscurity.
Plainly put, who you're with and what it's for are unknowns and likely to remain so regardless of what's written. Anything passed herein is not limited to solitary individuals, and trust is generally too freely given.