I'm surprised more of you haven't jumped on this - it is quite a nice mod and probably easier to execute than maybe appears.
Here is step by step process on how to wire this up
All you need is a relay, socket (ideally) and three diodes.
I like to use the compact Panasonic relays - good for 20A and much smaller/neater form factor that Automotive style relays.
You can also use the Omron style relays used in the later FI bikes - also compact (and OEM has built in resistor so can skip D3)
But a Generic 4 terminal automotive relay may also be used. (or even 5 terminal - just ignore the 87a centre terminal which will not be used)
Just be sure to identify the terminals appropriately for whichever relay you end up using.
I would advise a 20A mimimum rated device - although you could probably use 10A and still be comfortable for a single headlamp application.
Step 1.Prep first relay terminal by joining the three* diode cathodes (ends with the white stripe) together and crimping/soldering.
This terminal is for the 86 location in the relay socket
* Note that if your relay has built-in suppression diode or resistor, you may omit D3 and only require two diodes (see step 5)
Step 2.Crimp/solder the Anode of ONE of the three Diodes and a 14 ga wire together to another Terminal.
This terminal is for the 87 location of the relay socket.
(This wire will be the Output wire ultimately connecting to the OEM start Relay input)
Step 3.Connect the Anode of another of the three diodes to an 18 ga wire.
(This wire will ultimately connect to the White/Red starter signal wire)
Step 4.Heatshrink over the diode and wire from step 3
Step 5.Crimp/solder the Anode of the remaining Diode along with an 18 ga wire together to another Terminal.
This terminal will be for the 85 location of the Relay Socket
(This wire will be the Ground wire for the relay coil ultimately connecting to a common ground reference)
* If a relay utilizing built-in suppression is used, connect the ground wire directly to the termnal
without the additional D3 diode
Step 6.Install the three assembled terminals into the 87, 86 & 85 locations of the relay socket.
Of course plan ahead for whatever relay/socket you are using to ensure the correct locations are selcted.
Step 7.It is critical that the two exposed Anodes do not touch!
These should be physically isolated from each other and coated with something like liquid tape or heatshrink over the idividual components.
Step 8.Final step can be to tidy with heatshrink sleeve.
Installation:1. Remove the Blue/Yellow wire/Terminal from the input to the OEM Starter Relay and insert this wire/terminal into the remaining open location (30) in the new relay socket
2. Attach a Terminal to the Blue Wire and insert this in the OEM Starter Relay socket location from which Blue/Yellow was removed in step 1
3. Attach the starter wire from the new relay to the white/red wire of the OEM Starter relay (if your relay has two white/red wires use the one on the input side i.e. from the start switch)
4. Connect the black wire to a ground circuit wire (any) or battery negative.
That should complete the process and ready for test!
