here is a link to a 150cc service manual, download a copy.
http://aerox.us/roketa/arrow150_engi...ice_manual.pdf
look @ pg 50 of the manual (pg 57 of pdf) you can clearly see the white wire is full Vac charging power sent to the R/R, the yellow wire supplies reduced Vac power to the lights and the enricher. And of course, green is ground.
hope this helps.