When at idle the voltage is 13.2 and when it goes to 5k it is already 12.5 Instead of going up the voltage goes down. Any suggestions

here's a short video:
https://www.youtube.com/watch?v=moke_IOGebY

Regulator/Rectifier

Connect rect/reg output directly to battery terminals.

Will try that magg, if it doesnt help i will change the rect/reg

edit: which are the + and - wires on the rect/reg :D

Usually on the loom side green is -ve and red/white +ve.

I had the same issue last year, swapped the rec/reg and back up to 14v @5000 rpm, so that would be my first thought.

Not reg/rec.
Well, it still could be - but I have seen this before (and on mine). It is down to the impedance in the wiring loom. Greater voltage at the reg/rec causes higher current through the wiring loom and a bigger voltage drop before it gets to the battery.

Solution is to perform the mod where you wire the reg/rec direct to the battery (via a fuse obv!). I did this and all is peachy. Took about 20mins I seem to recall. Most of which was getting the rear bodywork off. I'll try to find the thread on here for you.

Also see here viewtopic.php?f=24&t=49827

everything is clear except the part with the fuse, i am an electricity cripple so pls help with the fuse :D