LED headlight bulb for a 1970’s bike?
Discussion
I fitted a led 'bulb' to a Honda hornet, lots of light but not all where you want it, lots of flare and quite a bit in the rear view mirrors of cars in front at traffic lights.
Your headlight. Reflector is set up for incandescent bulbs, the LEDs have the light source in the wrong place.
Could you add daylight running lights? Pretty cheap on evilbay
Your headlight. Reflector is set up for incandescent bulbs, the LEDs have the light source in the wrong place.
Could you add daylight running lights? Pretty cheap on evilbay
There are LED single round headlight options available. There's these mobs: https://motodemic.com/https://www.jwspeaker.com/products/applications/mo... but you can probably find plenty of similar things on eBay, Amazon etc. for cheaper. Had something similar on my Hornet (the previous owner fitted it, I believe it was actually for a truck!) and it worked well.
You could try http://www.norbsa02.freeuk.com/goffyWhyNotLEDs.htm
LEDs that are claimed to have the light source in exactly the same place as the originals.
LEDs that are claimed to have the light source in exactly the same place as the originals.
Biker 1 said:
I'm surprised you can't get exact LED replicas of H4/H7 bulbs - there must be a pretty big market for such things.
You can. I've got Osram H4 bulbs in my TVR. Even bought them in Halfords! Claim to be off road use only but my MOT tester said they gave good pattern and he couldn't fail them.
Eta: Here you go Clicky
Edited by Jordie Barretts sock on Wednesday 2nd August 08:16
Jordie Barretts sock said:
Biker 1 said:
I'm surprised you can't get exact LED replicas of H4/H7 bulbs - there must be a pretty big market for such things.
You can. I've got Osram H4 bulbs in my TVR. Even bought them in Halfords! Claim to be off road use only but my MOT tester said they gave good pattern and he couldn't fail them.
Eta: Here you go Clicky
Edited by Jordie Barretts sock on Wednesday 2nd August 08:16
Had a quick look on the bay of e and they are about £30 cheaper than Halfrauds though.
I bought these https://www.ebay.co.uk/itm/383193816047 for my 80's bike (lights not really having changed from the 70's bikes).
Bought those ones specifically as they don't have a big heatsink at the back so fit exactly like the originals and the LED location on them should match up with the originals so it doesn't create a nasty mess of light everywhere rather than a nice beam pattern.
Haven't run them at night yet though.
Bought those ones specifically as they don't have a big heatsink at the back so fit exactly like the originals and the LED location on them should match up with the originals so it doesn't create a nasty mess of light everywhere rather than a nice beam pattern.
Haven't run them at night yet though.
Jordie Barretts sock said:
Biker 1 said:
I'm surprised you can't get exact LED replicas of H4/H7 bulbs - there must be a pretty big market for such things.
You can. I've got Osram H4 bulbs in my TVR. Even bought them in Halfords! Claim to be off road use only but my MOT tester said they gave good pattern and he couldn't fail them.
Eta: Here you go Clicky
Something like my headlight (photo stolen off ebay because I don't have a photo of the back of my *actual* headlight) and the rubber sealing cap wouldn't fit at all so the inside of the lamp would be open for all sorts of nasty s
t to get in. 
I fitted an H4 LED bulb into my old Guzzi, works fine but I did have to bend the tabs over for it to fit as the bulb is longer than a conventional H4 and the headlight is a fairly shallow dish shape.
Then once bent over I had to devise a means of plugging in - I used crimped spade connectors; female to fit the bulb, male to fit the plug, 3 wires a couple of inches long.
Can't be certain if lights much better but looks brighter and uses less current, helping the 40+ year old charging system out.
This is what I used; https://www.amazon.co.uk/dp/B0BM3XCZGH
Then once bent over I had to devise a means of plugging in - I used crimped spade connectors; female to fit the bulb, male to fit the plug, 3 wires a couple of inches long.
Can't be certain if lights much better but looks brighter and uses less current, helping the 40+ year old charging system out.
This is what I used; https://www.amazon.co.uk/dp/B0BM3XCZGH
catso said:
Can't be certain if lights much better but looks brighter and uses less current, helping the 40+ year old charging system out.
Erm. It actually does the opposite. Older charging systems use shunt regulation which "shorts" the coils to regulate, this causes heat (in the stator) and heat in the reg/rec. The more regulation you need, the more heat you generate, this will eventually kill the reg/rec and can fry the stator.
So you actually want to use as much power as you possibly can to reduce the regulation and hence reduce the heat generated.
So with an old SCR/shunt based reg/rec the reason for getting LED bulbs should be for more light, not for a reduction in power usage.
Fastdruid said:
Erm. It actually does the opposite.
Older charging systems use shunt regulation which "shorts" the coils to regulate, this causes heat (in the stator) and heat in the reg/rec. The more regulation you need, the more heat you generate, this will eventually kill the reg/rec and can fry the stator.
So you actually want to use as much power as you possibly can to reduce the regulation and hence reduce the heat generated.
So with an old SCR/shunt based reg/rec the reason for getting LED bulbs should be for more light, not for a reduction in power usage.
My '76 Laverda had a stator based electronic ignition as standard (didn't need the battery to run) and a 32 amp hour battery.Older charging systems use shunt regulation which "shorts" the coils to regulate, this causes heat (in the stator) and heat in the reg/rec. The more regulation you need, the more heat you generate, this will eventually kill the reg/rec and can fry the stator.
So you actually want to use as much power as you possibly can to reduce the regulation and hence reduce the heat generated.
So with an old SCR/shunt based reg/rec the reason for getting LED bulbs should be for more light, not for a reduction in power usage.
It's generally accepted in Lav circles that the generator didn't have enough power to run a standard H4 headlight without eventually flattening the battery.
Those wacky Italians just stuck a larger battery on so you could get home in the dark from your local wine bar and expected you not to use the headlight all the time.
I don't think it actually HAD a regulator as standard - just that overly large battery that could handle moderate overcharging if it ever occurred.
Most Lavs these days have an after market ignition system - requiring an additional 300mA odd.
Before LED bulbs came out the accepted "cure" was to run a 20W parking/side light in the leadlight shell to be visible, and run on the sidelights unless it got proper dark. And not do long rides in the dark!
So LED bulbs help some bikes with inadequate original generators...
Fastdruid said:
Erm. It actually does the opposite.
Older charging systems use shunt regulation which "shorts" the coils to regulate, this causes heat (in the stator) and heat in the reg/rec. The more regulation you need, the more heat you generate, this will eventually kill the reg/rec and can fry the stator.
So you actually want to use as much power as you possibly can to reduce the regulation and hence reduce the heat generated.
So with an old SCR/shunt based reg/rec the reason for getting LED bulbs should be for more light, not for a reduction in power usage.
Here's what Fastdruid is referring to actually happening:Older charging systems use shunt regulation which "shorts" the coils to regulate, this causes heat (in the stator) and heat in the reg/rec. The more regulation you need, the more heat you generate, this will eventually kill the reg/rec and can fry the stator.
So you actually want to use as much power as you possibly can to reduce the regulation and hence reduce the heat generated.
So with an old SCR/shunt based reg/rec the reason for getting LED bulbs should be for more light, not for a reduction in power usage.
I tried recently to create a rev counter based on the generator output of my bike - it worked at low revs and stopped at higher revs, and worked higher up the rev range if I had the lights on. Weird. So I broke out the oscilloscope:
Here's me kicking the bike over. The blue trace is generator output - A nice slightly pointy sine wave.
Here's what happens just as the rev counter code stopped working...
The voltage starts dropping quickly to zero and back up again at a high frequency due to the regulator shunting (shorting out) the generator coils.
This breaks up the nice regular sine wave - it first starts happening on the trailing edge of each wave as shown.
And here we are at higher revs:
As generator output increases this progresses to the coils being mostly shunted (and therefore perhaps getting hotter than designed) with the occasional spike of voltage to keep the battery on a float charge.
So I redesigned the rev counter to work on the stator kill switch voltage instead.
Probably should have said better for the battery charging, with a lower wattage bulb I have more voltage for battery charging.
E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
catso said:
Probably should have said better for the battery charging, with a lower wattage bulb I have more voltage for battery charging.
E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
It's not Bosch electricals is it? That's what was on my Lav...E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
catso said:
Probably should have said better for the battery charging, with a lower wattage bulb I have more voltage for battery charging.
E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
Fair enough, I wasn't taking Italian electrics into account. E.G. on said Guzzi, running with a standard H4 bulb the battery is barely charging (if at all at lower revs) but if the light's off then I've more voltage to keep it charged, a lower wattage bulb sits somewhere in between.
My 80's Honda has a 335w (@5k) rated alternator (down from the earlier version which had a 350w one) and that would happily do everything as normal (ie lights on) plus heated jacket and grips!
Gassing Station | Biker Banter | Top of Page | What's New | My Stuff