P11 Headlight

Since getting the bike back together, I've ridden a little over 200 miles and gone through two headlight bulbs. Each lasted maybe 100 miles and then burned out. I put a voltage meter on while running and I don't see excessive voltage. Any suggestions? Are there better bulbs? These were 2 bulbs I picked up in Jacksonville for around $5 each I think. Has anyone converted a P11 to run a halogen bulb? I've seen references to others converting the old Lucas lights to halogen.

Are you sure the bulbs were 12V?

I bought a Lucas headlight reflector with bulbs a few years ago. When I hooked it up, it looked great - nice and bright.

Bulb blew out after a couple hours of running. That's when I discovered it was a 6V bulb. The '6V' on the shell was almost obscured by solder. The pilot bulb was 12V, however.

I have the 1968 Lucas catalog - Publication 400/68
there is a section for Matchless P11 and here is the cropped section for headlamp.

So page G18 gives the detail on the P11 59666A headlamp assembly.
And you will find this 59666A headlamp listed for P11 in the Norton Spares catalog 1963-1970.

Cant help with burned out bubs, but here is G18 details from 1968 Lucas catalog.

So now G18 refers to an N figure on page G5.
So here is figure on page G5.

Bulb choices you can find on the net, here is a crop from some Lucas bulb catalog.

So you can pick what brightness versus watt power you can supply.
British Pre Focus style P36d
some these might be yellow tint for Euro use.....and so the wattage repeats.
Someone have knowledge on these series bulbs

The bulb I just blew says 12V48/48W on it. So it is a 12V bulb.
I believe it's this one:
http://www.mapcycle.com/map/index.php/b ... anese.html


In the Waldridge catalog I see these options:
REGULAR TYPE
HEADLIGHT
12 Volt BULB414 $7.60

HALOGEN AND QUADOPTIC BULBS
HEADLIGHT
Halogen Headlight Bulbs for use in original British pre6focus light
units
12 Volt 45/40W BULB410H $21.94
12 Volt 60/55W BULB414H $21.94

Not sure if one of those Halogen ones can be used?

johnsiii88 said:

Since getting the bike back together, I've ridden a little over 200 miles and gone through two headlight bulbs. Each lasted maybe 100 miles and then burned out. I put a voltage meter on while running and I don't see excessive voltage. Any suggestions? Are there better bulbs? These were 2 bulbs I picked up in Jacksonville for around $5 each I think. Has anyone converted a P11 to run a halogen bulb? I've seen references to others converting the old Lucas lights to halogen.

Click to expand...

Typically, I find blown headlamp bulbs are a result of over voltage, not a bulb issue....no matter how carefully or low rpm you think you are achieving.
So, if you don't have an adequate, new, correct size battery for voltage spike absorbsion, you should get one.
Battery alone still may not be enough.
I recommend a new voltage regulator ....Podtronics, Tympanium and others. It is not worth trying to troubleshoot existing , vintage voltage components on the P11.
New regulator can be installed on the bottom of battery tray. I have used the Podtronics on several vintage bikes as Podtronics has the lowest voltage bleed for vintage bikes without a key switch. A P11 has a key switch, to isolate the battery, so this means any new style regulator would probably be fine. $50-70
hope this helps

If the bulbs are black it is too much voltage that causes them to blow, can be cured cheaply by fitting a suitable resistor in line of the bulb. HTH

I am going to look at putting an LED Speaker 8700 Evo2 light in a P11 Lucas SS700P headlamp shell.
Not sure if it will fit , but they are expensive enough to know the fit before purchase.
Anyone fit this light in a Lucas before.
I see some insanely expensive Speaker 8790 motorcycle headlamp available in a couple months - Yikes!

Looking at this desire to put a modern LED 7" bulb on a P11, I find a couple of items to allow this at a reasonable price.
couple of fit concerns as well.
It appears Emgo offers a British (Lucas) headlight shell that would allow me to cut my own ammeter hole that would better fit a Speaker LED 7" bulb.
Emgo available off Ebay and others ....Speaker LED also available off Ebay.
The stock position of the Lucas ammeter will interfere with the LED, so using the stock headlight is not good for my nice P11 original headlamp.
I can purchase an Emgo bucket and cut a hole slightly lower (further back) than stock. plus use a new ammeter, also new hole for hi beam indicator.
Might have to trim the ammeter studs as well, but since all pieces would be repro, no concern to me....just put the original headlamp aside.
I tried share a cutaway picture, but the scale may not be correct enough to be exact.....but pretty close.
I might have to put a spacer (maybe a rubber oring) under the face of the repro ammeter to allow clearance.

I think it is the vibration that gets the bulbs. Also the ammeters. Maybe try to mechanically isolate the headlight shell with rubber bushings?

batrider said:

I think it is the vibration that gets the bulbs. Also the ammeters. Maybe try to mechanically isolate the headlight shell with rubber bushings?

Click to expand...

I agree regarding vibration for the Lucas bulbs. However, I have been using a 12 V. 7 inch sealed beam automotive lamp for years without any more frequent filament failure than occurs in my old truck. They are not the brightest lamps, but these days, I do not have the urge to overdrive my lights.

Vibration fractured the welds around both of my headlight shell securing nuts. I do not see how any rubber bushings can be employed to dampened the vibes, and still have the shell hold its aim. But no matter, if you don't mind the slight loss of "purity", the sealed beam filaments seem to be up to the task.

Slick

Ordered a new Emgo Reproduction shell.....no holes except a bottom hole for wire harness.
Also ordered a new reproduction Lucas 12-0-12 1-5/8 ammeter.
I am not sure what to do about the $273 Speaker bulb LED yet.