Havsurf

Hello All, I'm a new member looking for some help on 1973 dt 125 not charging the battery, I have a wiring diagram and I'm trying to check the windings from the stater circuit. The diagram shows a green,white and black wire from the stater to the voltage regulator. The black wire is ground, I measured 500k ohms between white wire and black wire. The same between the green wire and black wire. I also tried to measure the voltage from the green and white wire while the bike was running. The voltage varies with rpm but nothing over .25 volts ac. Everything works well when the battery is fully charged but I have to charge the battery with an external battery charger. The battery is new. Any suggestions or point me in the right direct to receive some help? Thanks, Havsurf