Introduction
The headlamp of my Matchless G3Ls
Let’s face it, the headlights on old bikes (especially those still running 6 volt electrics) are not exactly dazzling are they? However, there are a few things that you can do to improve matters quite considerably and that is the objective of this quick ‘how to’ guide.
Ok, so you’re thinking “why not just put in a high wattage bulb?” aren’t you? Well that could certainly be an option in some cases (although it needs some careful thought), but lets just put the obvious to one side for one moment and look at some other options first.
This article covers the following topics:
- Introduction
- The headlamp and reflector
- The quality of the wiring
- Installing a headlamp relay
- Changing the bulbs
- Selecting the optimum wattage bulb
- An example on my Matchless
- Conclusions and your comments
The headlamp and reflector
Let’s start by looking at the headlamp unit itself. Over time, the outer glass may have become scratched and dull and the mirror finish of the reflector could well have lost its shine. Both of these will have a dramatic effect on the light output. Similarly, cheap reproduction or pattern headlight units are often not as good as the original (Lucas?) models, either in terms of the quality of the finish (shininess of the mirror etc) or on the actual beam pattern (how the light shines out onto the road). Either way, a nice new quality headlamp unit will make the world of difference to what you can see of the road ahead.
The quality of the wiring
Something else that can have a surprising effect of the headlamp brightness is the quality of the earth connection back to the battery. The electrical circuit between bulb and battery is made up half of the wiring and half of the return via the frame of the bike. Think about how many rusty joints there are between the two: bulb to headlamp reflector, headlamp reflector to headlamp case, headlamp case to forks, forks (via greasy bearings) to the main frame, etc, etc.
The wiring behind my Matchless' headlamp
A quick check can be made using a multimeter by measuring the resistance between the headlamp case (or reflector if accessible) and the earth connection of the battery. More than a few Ohms means that voltage is being wasted trying to get the current through all these dodgy joints, giving less volts left at the bulb to light up the elements. The best option is often to run a new cable from the earth connection on the back of the headlamp bulb holder direct to the earth terminal of the battery. This should eliminate any resistance and give the full battery voltage at the bulb.
Note that 6 volt electrical systems are far more susceptible to these kinds of power losses than 12 volt systems. Power (in Watts) is defined as voltage (in volts) multiplied by current (in Amps). You can therefore have the same power from a low current and high voltage, or by a high current and low voltage. A 60W bulb in a 6 volt system will need 10 Amps of current (quite high – you only get 13 Amps out of a mains outlet at home!) whereas in a 12 volt system it would only need 5 Amps.
The problem with high currents are that they tend to heat up the wires as they pass through and this all loses energy from the system. The higher the resistance, the higher the heating effect and the more power that is lost. This is the same reason why mains power on the national grid is delivered at low current but very high voltage so as to minimise the resistive losses on route. So a 12 volt electrical system (or 24 volts as used on trucks) is much more efficient than the old 6 volt systems used on most classic bikes.
Installing a headlamp relay
The wiring and connections inside old motorbike lighting switches (and also many cheap modern reproductions too) is often quite fine and poor quality. Power can therefore be lost here too in the same way as described above for bad earth connections. One way around this is to fit a headlamp relay close to the bulb (perhaps inside the headlamp case if possible) which has direct connections using high quality wire direct to the battery terminals.
The original switch is still used, but now rather than turning the current on to the bulb directly, it now only controls a much lower current to operate the relay which then in turn switches the high current to the bulb. It’s a relatively cheap and straightforward job if you’re reasonably competent with motorbike electrics. Of course for dual filament headlamps (with high and low beam) you will need two relays, one for each filament.
Changing the bulbs
Ok, so back to the obvious solution – changing the bulb. This isn’t just a case of the higher the wattage the better though! The type of bulb is also very important too. The old standard incandescent bulbs have been pretty much replaced now by modern halogen bulbs which give much more light output for a given power rating.
You should also consider the quality of the new bulb you buy. Now I’m not suggesting that you need to pay a ridiculous amount for some fancy ‘boy-racer style’ bulbs, but nine times out of ten, decent branded bulbs are probably going to give more light output and last longer than cheaper unbranded versions of the same thing. You pays your money and takes your choice as they say!
Selecting the optimum wattage bulb
When it comes to selecting the optimum wattage of the headlamp bulb, it has to be a compromise between the amount of light you want / need and how much power your poor old generator or alternator can give. The dynamo on my 1951 Matchless is rated at about 45 Watts – that’s 30 Watts (as standard) for the headlight, 3W for the tail light (no brake light fitted), 3W for the front pilot light and 2W for the speedo illumination. That comes to 38 watts in total leaving a few left over for charging the battery. Clearly if I changed the headlamp to a 60 Watt monster then supply would be less than demand and the battery would soon run down.
So we need to be sensible. Make a list of all the electrical items and bulbs fitted to your bike and write alongside their power (in Watts). Remember to include electronic ignition (if your bike has it) as that’s fairly useful to have working too! You can probably ignore the horn and such things that are used only intermittently. You should then have some idea of what sort of headlamp bulb power you can get away with, remembering of course that you need to leave some to recharge the battery.
Your riding style is also important. The full dynamo / alternator power will only be available when the engine is revving beyond a given RPM. So if you ride in lots of heavy stop-start traffic, bear in mind that the charging system will give less output on average that if you only ride up and down the motorway at speed all the time.
An example on my Matchless
Here in India, I’m finding it a little difficult to source appropriate 6 volt headlamp bulbs at the moment. I currently have a choice of two; a 18/18 Watt old style incandescent bulb and a more modern 25/25 Watt halogen bulb in which the low-beam filament has blow. Hmmm, difficult choice hey! So I thought I’d take the opportunity to see exactly how much difference in light output I got between the two bulbs.
The photos below show the results; both were taken at the same exposure with the headlight on full-beam with the engine not running in the car port outside my house. Whilst by no means scientific, they do give a good idea of the sort or difference you might expect.
The illumination from a 18 Watt (non-halogen) headlight bulb
The illumination from a 25 Watt halogen headlight bulb
I want to fit a 35/35 Watt halogen unit when I can get hold of one (in conjunction with some LED’s for the other lights), but I think this is about as far as I can go for my old bike. I’ll post a picture of the new light output when I do.
Conclusions
So fitting a higher-wattage high quality halogen headlamp bulb will make a big difference, but it’s going to be counterproductive if you’re bikes charging system can’t keep up with the increased demand. So make sure you select the wattage appropriately, perhaps in conjunction with some LED’s to save some Watts elsewhere, so that you don’t just end up stranded with a flat battery.
But remember that there are various other things you can do with your bikes wiring to improve the headlamp output in addition to the obvious changing of the bulb. These are free in that they don’t require any extra power, and are therefore more desirable first course of action.
[sc:disclaimer]
Hi James,
I was wondering about my lighting setup.
My motorcycle is fitted with the RM19 alternator and produces 80 – 100 watts. So I’m going to use your LED tail light setup and I’m left to decide on the headlamp. Battery is a Cyclone 12v and regulator/rectifier 12v Boyer Bransden. Pilot/Instrument bulbs also to be replaced by LED.
Do you think a 65/55W Halogen Headlight Bulb will be okay for this system? Any other recommendations? I made some calculations and think it might be fine…
Kind Regards
Petrus
Hi Petrus,
I’d guess that the 65/55W is probably borderline so will come down to how you ride the bike and your local roads; if you mainly ride on long open highway it should be fine, but around town in traffic it might not be.
Remember that if you’re battery runs flat your electronic ignition stops working and you’re stranded! Did you take into account how much power the BB ignition needs in your calc’s? I guess the alternator output you mention is maximum at higher engine speeds, so you probably won’t be getting that when stationary or going slow.
I guess what you really need is one of these to monitor the charge going into our out of your battery!:
https://matchlessclueless.com/store/meters/voltage-current-meter/
Regards, James
Thank you for writing this. For the past four years I’ve been wondering whymy bike headlight didn’t go on as bright as a car’s eventhough they use the same halogen bulb. I even take out one from the car and put it on the bike.
Right now I’m saving up for some HID upgrade (which I’m not sure is a good move but I’m desperate!!) and the thing you wrote about relays up there made me hit my forehead real hard. Many times. In quick succession. I used relays for the airhorn and spotlights. Never thought of using it on the headlight! Thanks again! 😀
Hi there. HID lights are probably not a good idea if you’re just thinking of installing a HID ‘bulb’ into your existing headlight. The light output is very different and so a normal reflector and lens won’t focus the beam properly, resulting in lots of glare for oncoming traffic. James 🙂
Some two weeks later I decided to do both! Put relays in for the headlight and took out the spotlights and replace them with two HID projectors in a custom-made housing. Still look like spotlights but with hi-lo function. 🙂
The halogen works better than it ever did, almost like the light output doubled.
But where there’s no streetlight, i use the bi-xenons. They were wonderful.
But that was not to last. The bi-xenon died last week. The ballasts couldn’t handle the vibration, I was told.
But the stock halogen? Never performed better!
So a decent halogen bulb that gets the full battery voltage (using relays) would seem the way forward then! 🙂
Can you help, I drive a triumph 68 t120 chopper, it drives fine but when i turn the lights on it kills the bike, is it possible to change the bulbs to an led bulb as it may not take as mush power, Battery is quite small as bigger size battery wont fit, but its still 12v, Im new to this but i hope you can help,
Hi John. Perhaps your battery is worn out so not storing enough charge. Check out this post on what the voltage should be:
https://matchlessclueless.com/electrical/general/battery-voltages/
LED bulbs will help disguise the problem, but won’t actually fix it. You may need a new battery or there could be a problem with the charging system. I have some new LED products that I’ll be adding to the web store over the coming weeks that you might be interested in though. I’ll email you some details…
Regards, James
Sir sirf aur sirf rectifier change kr lejea
I replace standard bulb with LED but quality of light is same. Kindly recommend how i can get a better focused light.
With my current light i can ride in city but it doesn’t work in countryside or off road.
Hi Rizwan. Sadly you are not going to get good light from any LED headlamp bulb – they just do not emit enough light to illuminate the road. You will need to switch back to a standard bulb, but get a good halogen model instead for better light output. Regards, James
Thanks James,
Light is better after replacing standard bulb but i am having problem with focus and length of light. I want focus and long bright light.
The best bet would be to go in for an all LED setup. you can do with just 3 W for the tail lamp and the speedo backlight. that gives you ample reserve current for the battery charging and the LED headlights that offer almost 100 lumen /watt.
Another alternative is to install a higher power alternator, if you have the technical skill to do it. Since it is an internal mod, it wont affect the looks, besides it will give you 12V system that is much more efficient and easy to maintain.
Hi Jairaj, thanks for your thoughts. Personally I would not go with a LED headlight; whilst LED headlamp bulbs are fine for daytime running, they do not have enough light output or the right output pattern to put enough light on teh road to see where you are going. But things are changing fast and no doubt there will soon be good LED headlamp options (although probably none that will work with a classic bike’s head light!). James
hi, i’m wondering what I can do to my newly purchased restored Suzuki ts125er to improve the brightness of the headlamp? the indicators aren’t brilliant either. the headlamp is more of a yellow colour and it hardly lights up the road and I think during the day it is a safety issue too. what do you think the maximum bulb is I could put in? it has a 6v battery. can this be exchanged for a 12v or will it melt the wiring? i’d be grateful for any suggestions please.
So generally.. It’s safe for the battery to replace a headlamp to a lower wattage..?
Hi TJ. Yes, replacing the bulb with a lower wattage unit is normally fine so long as the voltage regulation system is working correctly. If it is not then a lower wattage bulb (or LEDs) will mean a higher voltage at the battery which could over-charge it. But it will make no difference if the regulator is correctly set and working. The only exception is very early dynamo systems (pre-dating the Lucas MCR regulators) which used a resistance wire to manage dynamo output. These systems are more finely balanced and hence bulb wattages need to be selected accordingly.
Regards, James
Hi sir. My bike is Yamaha fz16 and the headlight specs is 12v 30/30W. If I instal heloneix 12v 60W blub, will I get a sufficient Bright ligth? Will it effect my rpm. Is the consumption of battery tolerable??
I have a 1968 Triumph Bonneville with a boyer conversion. I have to run with the headlight on during the daytime (state law). It wears down the battery. What changes do you suggest? The bike has positive earth.
Colin
Hi Colin. Good question – I have the same problem here in Hong Kong! First I would fit an LED rear light which will save you 5 watts straight off driving along, 21 watts when you have the brake on. That’s a good start! (Check out our store pages for the best available LED options). Then also fit LEDs in all the pilot, side, speedo and instrument lamps. Each one might only a 1 or 2 watts, but together they can add up.
LED headlamps aren’t a viable option at the moment. The ones that give sufficient light and a proper beam pattern take up just as much power as a regular halogen bulb. So for pure daytime riding, I would switch to a lower wattage halogen bulb – say a 25 watt bulb. You don’t need the light output during the day, but obviously this also gives you less light at night too, depending upon whether you ever ride just after dark.
But my own solution was to change the headlamp lens to one which had a pilot light built-in and to fit a really bright LED side light bulb into this. Then I ran with the bright LED sidelight on in the headlamp (rather than the halogen headlamp bulb) which lit up the lens as if the headlamp was on. This gave me the required daytime visibility, but without the constant load of the headlamp bulb being on. But obviously you would need to consider how that fits in with your local laws and regulations.
Hope this helps, James 🙂
hi , problem, I am replacing a 1996 Suzuki vs600 intruder headlight,the 2 bulb style, withan led headlight, the problem I have is that the old style has 2 separate wires for low beam, and the 3 pin connector for the main bulb, but on the led headlight there is only the 3 pin connector,which I have tried and it works,but only on low beam and I’m left with the 2 surplus wires,can you give me any idea of getting this led headlight to work both high and low beams and what to do with the wiring, I’m a novice at electrics and this is puzzling me,thankyou