Giantco Hunter 125 voltage issue

[rob78]

After purchasing a 60 plate with 7k I seem to be having an issue with thevoltage on the bike, it uses the 156fmi lump.

Despite changing the battery, the cdi unit, the rectifier and the stator I can't seem to get more than just under 12 volts meaning that with a bit of use the battery runs flat.

Having changed all the parts above I'm a bit lost as to what to do next with it as I thought that changing these bits would have sorted the problem but alas no, so if anyone could give me a suggestion what to try next it would be hugely appreciated as I'm a bit stuck.