I have done the following:- (and started up with the same annoying noise)
Unplugged the fan, both plugs.
Unplugged the alternator plug with power lead still on
Removed power lead with plug back in.
Removed power lead and plug.
Removed aerial plug
I haven't removed all of the above at the same time and tried starting it.
The battery terminals are on tight and all the earths are on tight.
I have attached a video obviously for you to listen to. Its a static type noise if you can hear it in front of the janspeed exhaust.
It didn't do it before I rebuilt the engine so it's obviously something I have done.
The alternator and battery have done 25miles. The old battery and alternator (altho they were fubar, well battery was) still made the noise. New battery and alternator fitted 2 weeks ago.
I had loom issues a while ago when the starter earth was attached properly and I melted my dads jump leads. That was sorted and had no other issues with loom since.
Thanks in advance