www.zxrworld.co.uk

I haven't started the bike in about 3 days and have just come to start in and the battery is dead,multimeter reading 3v

For it to be right down to 3v in 3 days you must have left something on........parking light ?

Sadly there is only a remote chance of recovering your battery..........you need to charge it using a proper bike battery charger such as Optimate or similiar

Under NO circumstance put it on a regular car type charger.....................

even if you do use the right charger is is VERY likely that your battery is only fit for the bin.

So you need to figure why it went so flat so quickly.
It is also possible that something is wrong within the charging circuit on your bike.............and your battery went flat because it wasn't getting a proper charge from the bike

F**k its a brand new battery,def didn't leave anything on,i recently put a second hand regulator on that i was told was working fine could this be the reason.

Chris1984 wrote:F**k its a brand new battery,def didn't leave anything on,i recently put a second hand regulator on that i was told was working fine could this be the reason.

Certainly could be the rectifier/regulator.
Should have tested it for yourself

i very much doubt you will recover a battery with 3v in it, you need a new one.it could just be the battery has died...........if its that new you should have a warranty on it for a new one anyways.
once you have got a new battery and got the bike running again use a multimeter to check what its charging at.