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Here are a couple tips to hopefully help some of you achieve a good clean install.

Voltage drop and Headlight output: Decreases lighting output by as much as 20%

Near a bulb's working design Voltage, a drop of only a half of a Volt results in a halogen bulb producing much less light. Many bikes have shown a 1 or even 2 Volt drop at the bulb, and I have confirmed this on my own Bikes. And this is also on new or like new Bikes.

After installing a relay kit, you will have a drop of ~.1 Volt, That's 1/10th of a Volt in case you miss the decimal.

There is always going to be some Voltage drop, This is normal with any switch contact. But this is about the minimum possible. This low Voltage drop is the proof that the system is a good one. All the wiring, connectors, and components are working as they should.

Headlight and Starter Switch’s

Headlight switches and starter (this is how your headlight turns off when you hit the starter button) switch’s are usually a weak part of a bike's electrical system. Even with a stock 55/60 watt bulb, headlight switches and connectors can break down early in a bike's life. This is because ALL of the electricity that goes to your headlight bulb is passing through those little switch contacts in your handlebar switch units.

Note: Some bikes do actually come with headlight relays, but the number is few. Even on newer Bikes.

When you are done completing this install, your headlights will function as they did with the dimming while using the starter button, everything is completely plug and play, no cutting or splicing here.

After installing the headlight relays, Your switches will now only be controlling the relays, and the current needed to run them is measured in milliamps.

So here I decided to clean up some old wiring I had added to a bike over the last couple years, and install one of my pre made wiring kits, so I can get some voltage drop readings at the bulb before and after the relay harness, and photos showing how easy the harness is to install.

My wife's bike will be next as I plan to add a 3rd fuse box to her bike, and clean up some wiring there as well. She had a full 2 volt drop at the headlight bulb, that has been reduced to .08 volts.

Here I am going to install the relay harness along with some other goodies that we will not be getting into, but they are all built into a single plug and play harness with 4 relays and 2 wires running to a secondary fuse box near the battery.

Normally in most cases you will connect the headlight relay harness directly to your battery.

( the rest of the wiring is plug and play for some aux fog lights, done with bullet terminals and pigtails to tap into the factory wiring so no factory wiring need to be cut on this bike, but its a little more complicated. So we will not be discussing it )

Thanks I hope this can provide someone with help in doing it themselves.

First we will get some voltage readings at the battery with the Bike running at idle.

And then the Headlight bulb with the Bike running at idle.

A full 1 volt drop in voltage at the Bulb.

We have a 7 inch headlight housing so there is plenty of room in this for all these relays I am adding.

There is also a harness for fairing mount and dual H4's, I am working on the H13 now but having problems getting wire seals for the special connectors for those bulbs.

The coil of wire at the bottom is for a set of switches we will use for additional running lights.

Here you can see the relay's and the single harness that runs through the back of the headlight housing.

This will run along the frame to the back of the bike with the main harness.

We are using the harness that will plug into a 3 circuit fuse box.

It comes as seen here, the terminals will be inserted tin the connector after we run the harness through the headlight housing.

In most cases you will be using the ring terminal type with the fuse holder.

Wire colors were different then what we normally use, we were just trying to get rid of some wire we had laying around.

Next we will connect the bikes original H4 bulb connector to the relay harness H4 coupler.

And then cover it with a large piece of shrink tube, as the original connector wiring is somewhat exposed.

You want to try and make sure you run this with the main harness if possible. and give yourself plenty of harness to turn from lock to lock without pulling or binding of the harness.

This relay harness is secured to the main harness in the headlight housing in a few spots, and you can see it secured to the main harness in this photo behind the radiator cap.

Now we are going to get everything tied up into place and tucked back in the housing so the headlamp will fit back in properly, You want to secure everything as you don't want any flexing of the wiring at the relay base, and nothing rattling around. we can then make the rest of our connections and finish routing the harness to the battery.

The 2 relays on the right side control the fog lamps, one is a main relay energized when the push button switch on the handle bar is on.

The other gray relay is a Mitsuba 5 pin micro (Not Cheap), it is energized while the side-stand is down and turns the fog lights off regardless of the handle bar switch. So the fog lights are always off when the side-stand is down and the bike is idling, they automatically come on when the side-stand comes up as long as the main switch is on.

I thought that was a kind of a cool feature.

(These relays also have there own smaller rating fuse)

I ran the wiring right down the center of the frame with the main harness on the bike, Then inserted my terminals in this connector here.

This connector here happens to be powered at all times, and does not run through a relay I have set up on the secondary fuse box.

Here is a picture of the secondary fuse box, it lays under the left side cover, wrapped with a piece of 3M adhesive lined foam to keep it from rattling around.

We could have put a tree clip on this and put it through the side of the tool box, but decided not to as it’s pretty tight in there.

Here is a photo of what we cleaned up, most of the relays in the headlight were under the seat at one time. Now only the horn relay, main fuse for the secondary fuse box and some connectors reside under there. Along with another fuse for the tender cable.

Voltage reading at the battery with the bike idling (this was after a coolant change as well, so it had been warmed up and idling a little higher this time)

These reading were taken at the battery tender connector.

And at the headlight bulb connector idling at idle.

Looking good with .05 voltage drop at the bulb.

Lighting output vs Voltage at the bulb

10.5V :  510 lumens
11.0V :  597 lumens
11.5V :  695 lumens
12.0V :  803 lumens
12.5V :  923 lumens
12.8V : 1000 lumens
←Rated output voltage
13.0V : 1054 lumens
13.5V : 1198 lumens
14.0V : 1356 lumens
←Rated life voltage
14.5V : 1528 lumens