OK,
There is a lot of collective wisdumb on the old googleweb, some of it may lead you astray.
I know of one modification that will work for any headlight set up. It takes a little bit of knowhow, but not a lot. And some room on the bike.
No it is NOT and HID upgrade. I just bought a used ST4s and the headlights were TERRIBLE. I asked at the dealer and was told "No there must be something wrong with you instillation. Those headlights should be OK"
So I set out to see what might have been installed wrong and to do the one fix I know from experience will work.
Sorry, should have taken more pictures but I didn't. Again there is already a lot out there for you to find.
I pulled all the plastic off and what did I find under that headlight bucket? Why an HID conversion. It looked like a nice pro job. All the wires were tucked away neatly. Everything secure. Problem was It did not put the light where I needed it.
With the low beams on it showed a crescent in front of my wheel but that was it. No fill light, no nothing. Even with no light for me to see by oncoming drivers would flash their lights at me like I had my High beams on.
Time for an HID ectomy. Biggest Trouble was they did not leave it so it could return to stock easily, so I had a little work ahead of me.
First, a little picture to help illustrate why an HID kit doesn't work. Look at the two bulbs here. That big long HID thing does not put it's light in the reflector where designed so the light is not put where the designers intended.
So what does work do you ask?
Very simple, some bigger wires bring real battery voltage to the headlights. I have done this on cars before and it makes a big difference there. I can only imagine that replacing the stock wires most weight conscience MC manufactures put in can only help all the more.
First, here is a shot of my headlight bucket with the proper bulbs in place.
To add bigger wires, you also need to add relays. You can get weather sealed 30 amp relays at Radio Shack, or I got these at Auto Zone. Don't forget a fuse holder at the battery too. Don't want to burn the bike down just because we want better headlights.
I believe in overkill here, so I went with 10 gauge wire where the run was common to both high and low beams and 12 gauge for the rest. Another thing to remember is that is you are increasing the size of the hot, just as much goes down the ground so upgrade those too (and I did run those all the way back to the battery too.
I tapped into the stock wiring to get the control wires for the relays, remember, I had a hack job to replace so this was not a big issue for me here. But you need to turn the relays on and off, so you will be doing this somehow.
Next I ran the 12 gauge from the headlamps back to each relay, yes one for low beam and one for high beam.
Here is one of the relays ready to be secured in the out of the way place I found for them.
On a motorcycle this is about the hardest part, finding a place to add the relays. Running the wires to the battery is the next. Make sure you don't pinch them or put the near any moving parts.
And on my ST this is where I found to hide the relays, on the bolt that secures the mirror on each side up under the nose fairing. This will keep them out of the weather (a good idea even though these are weatherproof relays)
I can not tell you for sure on this bike that this made my headlights brighter, because I was replacing the HID's. But I can tell you that I am no longer afraid to ride at night on this thing.
I hope this information helps somebody.
Happy riding all.
