Answer on wire is in the service manual...  connect white stator wire to green harness wire to increase battery charge rate. 

(green stator wire will then be unused)

"Friends RT2 has a white wire coming from the stator which isn't attached but looks like it was lol maybe Mark knows where it goes or what it might be for?"  

It shares its purpose with the white wire on your own RT2, Simon! 

I have a contact here in the UK who repairs oil pumps, but he is booked up until at least February. If your mate needs it quickly and he can stomach the postage costs (and GBP to USD exchange rate!  ), then maybe contact DEET for assistance.

Send me an email if you want the details of my contact.

You need to READ the service manual.  In the electrical section it explains that to increase the battery charging rate you connect stator white to harness green.  I'm repeating myself but not sure how to say it any clearer? 

Just tape up the white and don't use it.  It should not be exposed like that as it has AC power with engine running.

Headlight is not fused.  15 amps is too big a fuse for a magneto model.  Should be a 10 amp. Sounds like you might have a short in the battery operated circuits. 

Ignition is separate from lighting… unless of course someone has monkeyed around without any knowledge of what wires does what… there is why studying the manuals wiring diagram is so crucial……
These bikes aren’t too difficult, but you need to look at the manual wiring diagram… take your time… really look through it all… follow from source coil…
Sneezles61

I've experienced shorts between wires just by them being close together as they are in a wrapped harness. I've separated wires by cutting open the sheath or tape that is wrapped and the short goes away. Found no breaks in the insulation by running my fingers over them but when they are wrapped together show a short between 2 wires with an Ohm meter. 50 year old wire and insulation deteriorates. I've rewired 3 of my regular riders with harnesses from DEET. They should be good for another 50 years.

But I suspect you might also have something buggered up by a previous owner to blow a 15 amp fuse.

In my replies I said to read the service manual. Specifically the electrical section. The text.  The words.  (I did not mention the full wiring diagram at the back of the manual showing the white wire as it doesn't. ) 

Photos don't post right now or I'd send a screenshots of the information

The service manual is found in Tech Library:  yamaha-enduros.com/index.php/service-man...360cc-service-manual

Go to Chapter 5.  The text mentions the white wire in Section 5-8 Charging System (sub-section 1) on page 92 of the manual (page 93 of the PDF)  It solves a small part of the mystery of the white wire there by telling you the daytime battery charging capacity of the white stator wire compared to the green wire.

Next page (93 of manual, 94 of PDF) has a small sub-diagram that shows the white wire not connected to anything.  So if you want a picture, there it is.  (there is also a mini "connection diagram" back in Section 5-3...  mini-diagram shows white wire, but doesn't explain it yet)

Farther down that same page the text explains "How to Increase Charging Capacity" which involves swapping white for green as I already described.

If you continuing reading a bit, Section 5-9 Battery near the bottom of page 94 (95 of PDF) goes over the purpose of the white wire yet again.

 

I'm way behind so probably been said--but blown fuse will be from a short circuit not overcharging.