Using relays to upgrade your headlight.

[Searchguru]

The following information is a quick guide to the ‘dark arts’ of vehicular lighting. Current (no pun intended) UK legislation regarding headlights on motor vehicles dictates that the maximum wattage for dipped beam is 55-watts and main beam is 60-watts. The beam should not dazzle other road users but to my mind, a 100-watt beam correctly adjusted will not dazzle any more than a 60-watt beam would.

Suffice to say, if you were to upgrade your halogen headlight it would not be legal. However, the chances of this upgrade ever coming to light (pun intended) is slim. However, this upgrade is purely ‘for show use only’ as they say.

The problem you have with just a straightforward swap of bulbs from standard 60/55 to say a 100/80 is that the new bulb draws more current. There are other choices of bulb – 100/55, 80/55 etc. Back in the 80’s a friend of mine changed bulbs in his Alfa Romeo. Everything seemed fine until his steering column burst into flames! Suddenly it was a lot lighter and hotter in the car than outside.
Modern cars have wiring capable of handling this increased power but motorcycles still do not.
With modern cars (1990 onwards in most cases), the solution is to increase the fuse rating from say the standard 8 amp fuse to a 16 amp fuse. This means both dipped beam fuses and both main beam fuses. If you go 100/55 you only need change the high beam fuses.

Motorcycles and older cars use much thinner wiring to save weight and money, so changing the fuses is not an option as you may have an ‘Alfa’ moment.
The solution is to fit relays to the wiring circuit. The relay is really just a secondary switch, once fitted. If you flick your headlight switch to high beam, the power that would have gone to the bulb now goes to the relay. This effectively powers a switch inside the relay, which flicks over to provide full on power to the light. Your original switch is only coping with a minor draw of power whereas the relay is doing all the work.

Relays, wiring, fuses and connectors are available at many accessory shops but they are not too expensive. You need one relay per circuit, one for dipped and one for main, so most bikes need two per headlamp. The diagram is hopefully self-explanatory but to clarify:
Site your relays where they can stay reasonable cool. Mount inside the fairing, under the tank or in the seat hump. Buy the ones supplied with a mounting bracket and site them so that the terminals point downwards. This is to reduce the likelihood of water ingress.
The wiring you need is for a max load of 17.5 amps. You’ll need some black, red and two colours that will be high and low beam circuits, the choice is yours or match the original colours.
You need to fit 16 amp fuses to each of the power leads from the battery to the relays.
You will probably have to upgrade the terminal plug to the bulb, as the original plug will have the original weedy wiring.
The crimp-on terminal connectors you need for the diameter of the wiring used are blue, however, soldered connectors are obviously better. Don’t forget insulators.

Wiring diagram in attachement (hopefully).

I have modified both my ZZR1100 and Yam XTZ660. The ZZR is a slightly tidier installation as I learnt from doing the XTZ. I got relays, fuse connectors, wiring and crimp connectors sufficient for both bikes for about £25. They both have 100/80 bulbs as have both of my cars. The bulbs last forever for some reason, which is a good thing as they are a bit more than standard.

[neracarken]

Putting these relays in is a good thing even with standard bulbs, as it means much less voltage drop from battery to light. My son found a GREAT improvement when he did it on his Ducati. As stated, the wiring isn't so good on some bikes, so putting shorter heavier wiring to carry the load is A GOOD THING.

[twolitre]

Relays are very useful items and can be used to ease the load on 'tired' switch-gear or when adding extras which might, for example, overload the ignition or other switch.
  Using them to enable the use of equipment which might cause accidents , such as over-bright headlamps is a selfish reason.  Have you never been hit in the face by (perhaps correctly set) over-bright lamps when the oncoming vehicle bounces over speed ramps etc.?
  If the standard headlamp bulbs are not bright enough perhaps you should slow down!  Or perhaps it is time to visit an optician!

[Searchguru]

twolitre,
If you are being hit in the face by other people's headlights, then they either need to tighten up the fasteners or you need to give them more space when they are negotiating speed humps!
Perhaps you should vent your spleen at those whose headlights are falling off everywhere.
As previously stated this modification is not legal but then nor is exceeding a speed limit...........

[twolitre]

My complaint is not about my LEGAL headlamp!  I can see perfectly well at legal speeds in the dark and I feel no need to travel faster.  My question is "WHY do YOU need brighter headlamps which can be a nuisance or danger to others?".

[Searchguru]

twolitre,
You missed the humour intended in my previous post. I did not mention your speed, headlight or its legality.

In answer to your question "WHY do YOU need brighter headlamps which can be a nuisance or danger to others?" is as follows -  
I can see MUCH BETTER at legal speeds with my correctly adjusted (66% brighter) main beam.
It is PURELY SELFISH of me to ride with better, brighter headlights but I NEVER get 'flashed at' by other road users.
You will probably say that is because they are frantically trying to stay on the road with their hands clasped to their blood soaked eye sockets. I say it is because it is not an issue with other road users.
I would rather see what is lurking in the shadows at a distance, where I can do something about it, than see it when its too late.