Halogen Headlight Conversion

warpedscout · Mar 25, 2011

OK,

I may have gone a little overboard while getting my Commando and bought a halogen 7" Lucas Tri Bar headlight. I really liked the vintage look of it and it fits and looks great on the bike. Only issue is I am not sure how to wire it up correctly since the bike is a positive ground. I made a set of wires to do a quick hook up to see it work and could not get it to work. I know I will have to get the halogen connector but just wanted to see if anyone else had done this, searched the forum and could not find any technical info on this. Also, this light does not have the hole for the running light, I figure the heat from the halogen would probably burn it up, would the running light be wired directly to the halogen to make it do double duty?

Any information would be appreicated!!

cash · Mar 25, 2011

I don't think it matters as a lamp a is a lamp the current can flow either way, LEDs are different, they are pole senitive.

Cash

bluto · Mar 25, 2011

I converted my bike to H4 and it made a big improvement for night riding. The bulb does not care about polarity as was said. Be sure to buy a quality/heavy duty H4 connector, the cheap ones melt...and you will have to give up the pilot bulb unless you buy another H4 reflector set up for one, they do exist. The H4 plug wiring is standard for ground, low beam, and high beam as shown in the picture though the colors will be different for an aftermarket plug and the Norton wiring. A standard H4 bulb pulls 55W vs. 45W stock and from what I've read some here have had this lead to inadequate battery charging with the stock single phase alternator, especially if a lot of riding is at low rpm but have not had this problem personally with a mix of urban and rural riding...if it does happen 45W and even 35W H4 bulbs are available, scooters use them.

L.A.B. · Mar 25, 2011

warpedscout said:
I made a set of wires to do a quick hook up to see it work and could not get it to work. I know I will have to get the halogen connector but just wanted to see if anyone else had done this, searched the forum and could not find any technical info on this.

Halogen headlamps (either optional or for specific markets) were fitted to Commandos from 1972-on, so if it is wired correctly then it should work, my own Mk3 Commando has a halogen headlamp unit.

warpedscout said:
Also, this light does not have the hole for the running light, I figure the heat from the halogen would probably burn it up, would the running light be wired directly to the halogen to make it do double duty?

The halogen bulb wouldn't burn a running lamp (my halogen headlamp has a running lamp) so you will either have to do without it (probably a good idea, as the brighter halogen lamp will put more strain on the battery and charging system), or modify the reflector?

warpedscout · Mar 25, 2011

Cool,

Thanks for the replies. So essietally I will use the positive ground to the headlight casing as the ground (black wire) and figure out which of the wires are low and high beam (Have to hook up my old light).

Will be running by the parts store today to do this then.

Put my head oil lines on last night and a new tach cable, having to pull the caliper puck out of my front brake (drilled it last night and placed in freezer so I can heat it up tonight and hopefully get it out)!

Thanks again!!

bluto · Mar 25, 2011

warpedscout said:
Cool,

Thanks for the replies. So essietally I will use the positive ground to the headlight casing as the ground (black wire) and figure out which of the wires are low and high beam (Have to hook up my old light).

Will be running by the parts store today to do this then.

Put my head oil lines on last night and a new tach cable, having to pull the caliper puck out of my front brake (drilled it last night and placed in freezer so I can heat it up tonight and hopefully get it out)!

Thanks again!!

I would not connect the H4 ground to the headlight shell (the shell itself may not be grounded well), instead wire it to the the ground wire that fed the original bulb....on my bike I used modern bullet connectors on the bikes wiring harness and the new H4 plug and connected them wire to wire... ground, low beam, high beam. If you want to keep the harness original Lucas bullet connectors are still available but I've had better results with the modern type like these

Ron L · Mar 25, 2011

If you have the stock wiring harness, you should have a Blue w/red tracer, Blue w/white tracer and Red wire running to your original bulb socket. If you buy a nice heavy duty connector like Cash shows you will need to connect the Red wire to the ground tab (left), the Blue w/red to the LO (top), and the Blue w/white to the HI (right). If you buy the cheaper connector with thre wires coming off, they are usually all three black. I would mark them or use color coded bullet connectors.

I highly recommend you couple this modification with adding relays for the healight. Drawing enough juice through the Lucas switches to run a 60/55 watt halogen bulb probably won't be any brighter than the old Lucas wax candle. There are several threads on doing this by making your own, or Greg (Decent cycles - Norbsa48503) makes a nice, neat kit.

warpedscout · Mar 26, 2011

OK, got the socket for the H4 and some bullet heat shrink connectors and all hooked up. Light works when I turn it on and do hi and low beam but the lo is really loooooooowwwww!. I searched the forum on the relay install and saw where hotbot posted a pic of his but just confounded me. Is there any step by steps on how to build and connect a harness instead of buying a kit?

Also having trouble with my left lucas switch, only wants to stay in one position, the other position it just jumps back to center. Will be trying to figure that out later after I have cleaned up my brake caliper (which I just pried the inside piston out of after three days of banging, drilling and tapping and thankfully did not damage any of the surfaces)!

daveparry · Mar 26, 2011

but the lo is really loooooooowwwww!.
--------------------
You've probably wired the plug wrongly, maybe you put the earth in the centre?
Dave.

warpedscout · Mar 26, 2011

I plugged the ground wire to the positive ground, and followed the wiring for hi and low beams. When I turn on the low beam it seems to fade then hold. I still do not have the bike running but the hi holds steady, would just like to put together a harness with the relays so I do not have any issues later.

daveparry · Mar 26, 2011

Best get it working normally first before you start altering the wiring for relays or you won't know where you are.

L.A.B. · Mar 26, 2011

warpedscout said:
Light works when I turn it on and do hi and low beam but the lo is really loooooooowwwww!.

That sounds as if you could have got the Hi and Ground wire connections reversed?

bluto · Mar 26, 2011

daveparry said:
but the lo is really loooooooowwwww!.
--------------------
You've probably wired the plug wrongly, maybe you put the earth in the centre?
Dave.

yep, agree...sounds like it is wired so that the low and high beam filaments are in series, ground is common so this would be easy to do

warpedscout · Mar 26, 2011

I got the switch working right now, don't think the connection was good at first. Works like a charm now!

RoadScholar · Mar 26, 2011

If you have an OE wiring harness you have a shaky platform for adding anything that draws more power. I suggest that you break and remake all your connections and evaluate the junctions between the conductors (wires) and the male/female connectors.

Do a Google search on "skin effect" to understand how electons flow on your wires.

Just so you (all) get it the OE Commando harnesses are now approaching 41 years old, great service..., but too much. Start thinking replacement.

RS

rick in seattle · Mar 26, 2011

Bill,

Your comment about the need to replace the OEM Commando loom is certainly true; the wet, salty environment seen by these wires corrodes the copper at the connector junction. Forty years of service is asking a lot.

However, your reference to skin effect is a bit confusing. Skin effect is only a high-frequency effect; to get skin depth to be on the order of the wire diameters, frequencies of 1 MHz or higher are needed. Skin effect plays no role in automotive electronics; we're strictly in the DC realm.

Ron L · Mar 27, 2011

Just so you (all) get it the OE Commando harnesses are now approaching 41 years old, great service..., but too much. Start thinking replacement.

Excellent point. And making your own can eliminate many feet of unnecessary wire and many connectors that are not needed. Also you can separate circuits to individual fuses and add relays for headlights, ignition, and horn. Improved wire with original color codes is available so following a factory wiring diagram for trouble shooting will still be possible.

bluto · Mar 27, 2011

Ron L said:
If you have the stock wiring harness, you should have a Blue w/red tracer, Blue w/white tracer and Red wire running to your original bulb socket. If you buy a nice heavy duty connector like Cash shows you will need to connect the Red wire to the ground tab (left), the Blue w/red to the LO (top), and the Blue w/white to the HI (right). If you buy the cheaper connector with thre wires coming off, they are usually all three black. I would mark them or use color coded bullet connectors.

I highly recommend you couple this modification with adding relays for the healight. Drawing enough juice through the Lucas switches to run a 60/55 watt halogen bulb probably won't be any brighter than the old Lucas wax candle. There are several threads on doing this by making your own, or Greg (Decent cycles - Norbsa48503) makes a nice, neat kit.

The H4 alone was a BIG improvement on my bike even without the relays, and made it even better with a Silverstar bulb....the uber bright 55W H4 bulbs typically are short lived on modern vehicles but am hoping mine will last much longer with the low voltage at low rpm Lucas system :wink: Eastern Beaver sells relay kits or parts if you want to make a DIY kit and there is good info on how it all works at http://www.easternbeaver.com/Main/Stuff ... _info.html

Halogen Headlight Conversion

warpedscout

cash

bluto

L.A.B.

Moderator

warpedscout

bluto

Ron L

warpedscout

daveparry

warpedscout

daveparry

L.A.B.

Moderator

bluto

warpedscout

RoadScholar

rick in seattle

Ron L

bluto

Similar threads