Headlamp Relays

for brighter lights

 20th June 2003

The R1100RT, like most motorcycles, doesn't have wiring and switches heavy enough to get the full voltage onto the bulb, consequently the light output suffers. Fitting a higher wattage bulb is often disappointing because the voltage dips even further due to the additional load on the wiring. Fitting headlight relays will solve that problem and give your bike the lights it deserves.

The surprising difference headlight relays and a 80/100w Halogen bulb can make (this is on dip beam).

Testing:

Below are some voltage reading taken directly from the bulb terminals of my R1100RT, battery voltage with the engine running was 13.86v

55/60w bulb without relays: 12.5/12.3v

55/60w bulb with relays:      13.6/13.4v

80/100 bulb without relays:  12.4/12.0v

80/100 bulb with relays:       13.5/13.3v

As you can see from the figures above, using relays and heavier than stock wiring can increase the voltage to the bulb by between 1 and 1.3v. That doesn't sound very much, but it makes a big difference to the light output because at 12.82v the light output of a Halogen bulb drops by more than 15%; at 12.1v it drops by a third!

Headlamp relays wiring diagram:

Below is the headlamp relays wiring diagram for the R1100 series motorcycle.
Click here to download a printable A4 version in MS Word (Zip file - 175kb)

The colour codes shown above are for the R1100 series motorcycles. I strongly advise using them as you will find yourself becoming very confused wiring the relays in just one colour. Other motorcycles may use different colours but, provided you follow the diagram above, it will work just the same.

Everything you need for this project except the Durite bulb connector is available at Vehicle Wiring Products Ilkeston, Derbyshire. They do stock a bulb connecter (part number 5736), but it is not quite as good as the one made by Durite (part number 0-539-51), Try your local motor factors for the Durite part.

Basic part list:

2x 30amp auto relays

2x Durite headlamp sockets, part No: 0-539-51

1x Black insulating tape to wrap the wires up

1x Wired inline fuse holder + 15a fuse

Heat shrink tubing

Wire: 2 meters 2.0mm Red

          2 meters 2.0mm Brown

          1 meter   2.0mm White

          1 meter   2.0mm Yellow

How to put it together:

I recommend soldered all the connections to cut out any possibility of voltage drop over bad connections.

Slip heat shrink tubing on the wires before soldering the wire on to the relays. When all the connections have been made and tested they can be shrunk down.

Below is the Durite headlamp sockets I recommend, part No: 0-539-51. You will need two kits, one to go on the headlamp bulb (female) and one which you will modify to plug in to the existing motorcycle headlamp coupler (male).

Brass strip from a model shop is soldered in to the connector terminals to make a male plug, see the left hand coupler below.

Male connecter to fit to the bikes wiring on the left. The new headlamp connector is on the right.

Here are the two relays super glued together, the wires have been soldered on and the heat shrink tubing shrunk down.

This shows the relays tie wrapped in place, just in front of the radio box on the left hand side. The wiring has been been wrapped in tape for neatness and a little more protection, then tie wrapped to the frame.

This shows the male connector pushed in to the bikes headlight plug and the new headlight plug fitted.

Importantly, should anything fail, it is very easy to return to the bikes original wiring.

Very important, the inline wired fuse. It's located as close to the battery as possible. The wire is quite stiff so it stays where it's put. The terminals on the battery are soldered to the wire ends - not crimped.

Notes:
1:- There is no Negative return from the bikes original bulb connector to the relays negative looping. This is not a mistake, it's just not needed.
2:- Most important - Do not omit the inline fuse from the battery feed.
3:- The position of the relay terminals can vary, check your relays carefully and make a diagram to suite.

4:- It's quite ok to put headlight relays on any bike, but I don't recommend raising the bulb wattage above standard if the headlight has any plastic components, it can lead to a melt down, also in your country, it may well be illegal!

Lamp tests:

Lamp tests by Auto Express November 2007, you can read about them here.

High output standard wattage Lamp:

The 'Philips X-treme Power' H4 Lamp has been voted accessory of the year 2007 by Auto Express.

"it put them all, literally, in the shade. Based on the light 75 and 50 metres ahead of the driver, the best beam rating the rest could manage was 107, but the new X-treme hit 146 a massive difference easily seen on the light-tunnel wall."

Philips X-treme Power +80% lamp, available in both H4 and H7 fitting.

Amendments:

28/11/07 - Auto Express lamp tests Nov 2007 added

01/11/07 - 'Recommended lamp' added

13/09/07 - Minor re write

29/10/05 - ***Caution! UK users***, If you mask off part of the headlamp glass to block the left hand dip while riding abroad, I strongly recommended you use a standard 55/60w lamp, This is after a friend running a high wattage lamp suffered a crack in the headlamp glass. The crack followed the edge of the black tape mask, Its suspected the black tape absorbed the heat from the lamp and caused uneven expansion, cracking the glass.

18/03/05 - If you would like the benefits of headlamp relays but can't find the materials to build your own, you could try, The Eastern Beaver Company Headlight Relays he says he will ship anywhere in the world.

 Any modifications you carry out on your machine are done so entirely at your own risk

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