LED Idiot Lights -- Lumens?

[monkeyodeath]

I'm in the process of putting the old dash back on my 1000SP and I'm interested in getting some LED replacements for the existing wedge bulbs in the idiot light cluster.

My question is -- does anyone know what specs would make for a decent replacement LED bulb? I've seen 194 LEDs recommended on this board for their lack of polarity requirements, but those are rated at 100+ lumens compared to the 74 LEDs, which are rated at only 17 lumens.

Obviously I'd like something brighter than the stock idiot lights but not sure if a 100+ lumen bulb is overkill for the application - or maybe it makes sense to use those but a smaller bulb for the high-beam indicator idiot light?

And while I'm asking, does it matter what the degree throw of the light is? I'm thinking narrow makes more sense but I'll admit to not being an expert on these things.

[nc43bsa]

Since you are not looking at the LED itself when you're riding (you're seeing the lens, which is lit by the LED), I wouldn't be too concerned by the illumination angle.

As far as the brightness, I'd choose the brighter LEDs for the indicators that are imperative to be seen readily in daylight, and dimmer ones that are primarily seen at night.  ie, Oil Pressure, Turn Signal get bright ones;  High Beam, Low Beam get dimmer ones.

Since you didn't mention getting new lenses, you may have to experiment with how bright the LEDs need to be, depending on how well the old lenses pass light. 

Also, white LEDs don't work well with colored lenses due to the physics of how they produce the light, so the red lenses will need red LEDs, green lenses, green LEDs, etc.

https://www.lensblx.com/what-are-the-common-misconceptions-about-using-white-leds-in-red-lens-lighting.html

[Kiwi_Roy]

I have been recommending the 194s for idiot light replacements for a long time, the first time I used them was for the T shaped dash for a VII Sport
I threw away the miniature lamp holders the bike came with and JB Welded th lamps into the fitting
I have used 194s by the hundreds for m/c dash and other industrial applications
https://www.superbrightleds.com/194-led-bulb-1-led-miniature-wedge-base?queryID=bc6ee7499afcc40e1dd2221ff724c721
I don't think type 74 would be so waterproof.
https://www.superbrightleds.com/catalogsearch/result/?q=Lamp%20type%2074&categories=Vehicle%20Lighting&base=E10%20%28Miniature%20Base%29~74
they come in 2 angles 90 or 120, I use all 90 degree.
If the 194 is too bright for you its possible to add a series resistor but i have never done this on a bike.
Yes it's great that polarity is not an issue, they have a 4 diode bridge rectifier in the base.
They are nice and bright for visibility in bright sunlight.
If you make a dash 1/8" thick you can JB Weld the lamp in so its flush with the surface
You can order lamp holders but i always solder the wires direct to the lamp, they will outlast me for sure.
Sometimes a lamp holder will lose contact if the wires are tight, solder always works.

A couple of points though.

They do not draw enough current to activate the thermistor type Low Fuel sensors so leave one of the older Incandescent lamps in parallel to create the heat thermistor needs.

Use a lamp of the same colour as the bezel, a green lamp will not show through a red Bezel, use a red lamp.

[Kiwi_Roy]

Since you are not looking at the LED itself when you're riding (you're seeing the lens, which is lit by the LED), I wouldn't be too concerned by the illumination angle.
The 194 can be installed without a bezel or lamp holder, I have often JB Welded 194s through 1/8" aluminium, the step in plastic makes them flush with surface
https://www.superbrightleds.com/194-led-bulb-1-led-miniature-wedge-base?queryID=bc6ee7499afcc40e1dd2221ff724c721

As far as the brightness, I'd choose the brighter LEDs for the indicators that are imperative to be seen readily in daylight, and dimmer ones that are primarily seen at night.  ie, Oil Pressure, Turn Signal get bright ones;  High Beam, Low Beam get dimmer ones.
I use 100kohm resistor on 24 Volt circuits.

Since you didn't mention getting new lenses, you may have to experiment with how bright the LEDs need to be, depending on how well the old lenses pass light. 
It's possible to dim them if required by adding resistor in series
Also, white LEDs don't work well with colored lenses due to the physics of how they produce the light, so the red lenses will need red LEDs, green lenses, green LEDs, etc.
I agree with this, I always use the 90 degree option

https://www.lensblx.com/what-are-the-common-misconceptions-about-using-white-leds-in-red-lens-lighting.html

[Antietam Classic Cycle]

All I know is: I've used these LEDs in the warning lights of six different motorcycles (five Guzzis and a Cagiva) and they've made a huge improvement over the original bulbs. The warning lights are finally visible in direct sunlight!
https://www.superbrightleds.com/74-led-bulb-3-smd-led-miniature-wedge-base
A little installation tip: Use a jewelers file to knock the sharp corners off, it'll make them much easier to insert into the bulb holders.

If you still have the original Bosch charging system, then you will need a "bootstrap harness" that connects between the charge warning light terminal on the diode board and a switched terminal on the fuseblock. Otherwise the system may not charge. Available from Gregory Bender.

[bmc5733946]

Superbrite LEDS has pretty much every bulb you could want in whatever size came standard in your bike. I found replacements for the tiny bulbs in my MILLE dash there. I didn't have to modify anything in my dash. I don't remember the numbers. They usually go by base size. Be sure to use the same color led as the lens in the dash, red for red, green for green. I used red for my instrument lights because I could, looks great at night. At my age I don't ride at night as much as I used to. Hope you get it all worked out.

I was hoping Antietam Classic Cycle would stop by. I used the number 74 single smd bulbs for my bike.

 

Brian

[Kiwi_Roy]

I think from memory the resistor to replace the charge light is ~ 18 Ohms 4 Wats

[Dukedesmo]

Quote from: nc43bsa on June 05, 2025, 07:49:03 PM

As far as the brightness, I'd choose the brighter LEDs for the indicators that are imperative to be seen readily in daylight, and dimmer ones that are primarily seen at night.  ie, Oil Pressure, Turn Signal get bright ones;  High Beam, Low Beam get dimmer ones.

___________________ ___________________ ____

Agreed, I've got Translogic dash/gauges on my Ducatis and whilst they are very good the LED indicators (all red BTW) are very bright, even on the dimmer of the 2 settings.

This is fine for indicators and stuff that you need to see but I find the High beam LED indicator too bright in that it dazzles when riding with it on at night. Initially I taped over it to avoid being dazzled but then I can't see it.

Luckily I bought a new helmet a couple of years back, an X-lite Ultra carbon, which has a wider chin bar than my previous Arai and so, effectively and conveniently blocks it from view when my head is in the 'ahead' position.   

[Kiwi_Roy]

Buy half a dozen 100 Kohm 1/4 Watt resistors and add one in series with one of the leads to cut down the voltage the lamp sees that will dim it down.
If it's too dim try 2 x 100k in parallel (50k)

[Kiwi_Roy]

Superbrite LEDS has pretty much every bulb you could want in whatever size came standard in your bike. I found replacements for the tiny bulbs in my MILLE dash there. I didn't have to modify anything in my dash. I don't remember the numbers. They usually go by base size. Be sure to use the same color led as the lens in the dash, red for red, green for green. I used red for my instrument lights because I could, looks great at night. At my age I don't ride at night as much as I used to. Hope you get it all worked out.

I was hoping Antietam Classic Cycle would stop by. I used the number 74 single smd bulbs for my bike.

 

Brian

Here's something else Superbright sell, 2 inch work lights, a pair of these on front greatly enhance the bikes visibility for safety and when following your buddy can see you in his mirrors a mile back.
I have a pair on my V7 just below the headlight the integral cable is just long enough, no need for the additional wiring harness
https://www.superbrightleds.com/catalogsearch/result/?q=work%20lights&wattage=10%20Watts
I used a pair of 6 Amp diodes, 1 from High beam, 1 from low beam to power them without having to run new wiring. the diodes ensure they come on with the headlight on High or Low beam.
Mine are the 30 degree beam angle
The V7 came with several unused 6mm pre-tapped holes under the triple tree allowing me to add a simple aluminium bracket for lights and a pair of decent Fiaam horns.

[Gliderjohn]

Recently replaced all the lighting including dash (T-3 police version with the big funky dash with little lights) with all bulbs from Superbright. Very pleased. Can actually see idiot lights in all but very bright, direct sunlight. headlight greatly improved.

[Wayne Orwig]

Buy half a dozen 100 Kohm 1/4 Watt resistors and add one in series with one of the leads to cut down the voltage the lamp sees that will dim it down.
If it's too dim try 2 x 100k in parallel (50k)

100 ohm, or 100K ohms?

100K would likely make it unusably dim.

[Wayne Orwig]

I think from memory the resistor to replace the charge light is ~ 18 Ohms 4 Wats

At one time I'm sure one person used a 47 ohm, 5 watt. Not sure that is the best value though.

[wirespokes]

Snowbum, the airhead guru, besides having done many other things, ran an electronics repair shop. His site delves (deeply) into anything and everything about airheads, including the Bosch charging system which is identical to the older Guzzis. He says a 470 ohm resistor was commonly used across the charge light leads as a safety measure for a blown bulb. Here's his page on that:

https://bmwmotorcycletech.info/genlampresistor.htm

[Antietam Classic Cycle]

This is what Greg Bender uses in his "bootstrap harness" that I wrote about previously: "Connects the rectifier to fuse number 5 to bootstrap the charging system. Comes complete with 2 watt, 82 ohm resistor soldered in place (as original)."

[Kiwi_Roy]

We seem to have a wide range of resistor values. 47 Ohms 5 Watt, 82 Ohms 470 Ohms and I have no idea what the resistance value of the original charging light was when cold, at key On it would have delivered a spike of current.
Using a Lemans II as a typical, the lamps are 1.2 Watts
http://www.thisoldtractor.com/guzzi007/schematics/1978_LeMans_II.gif
at 12 Volts 1.2/12=100 milliamps but the current at cold would be several times that.
As soon as the alternator starts the Voltage across the lamp will drop.
The thing is you don't want to generate too much heat if the key is left on without th engine running
47 Ohms would deliver 3.06 W
82 Ohms would deliver 1.7 W Greg Bender
100 Ohms would deliver 1.44 W
120 Ohms would deliver 1.2 W Kiwi Roy (my revised pick)
220 Ohms would deliver 0.65 W
470 Ohms would deliver 0.3 W Snowbum
Take your pick

[Kiwi_Roy]

100 ohm, or 100K ohms?

100K would likely make it unusably dim.

Yes Wayne, you are right again, I should have used my Ohms Law, how about 2.2K for 5 milliamps
Roy

[wirespokes]

The thing is, that once the alternator is kickstarted, be it normally or with a resistor, it self energizes. So the bulb or resistor is only needed at startup or low revs.

[Wayne Orwig]

The thing is, that once the alternator is kickstarted, be it normally or with a resistor, it self energizes. So the bulb or resistor is only needed at startup or low revs.

And I am certain that there is often enough residual magnetism in the rotor that it starts itself without the resistor to boot itself up.

[larrys]

I replaced all of the lights in my Cal with LED's. I can actually see the dash lights during the day and the turn signals are like strobes on an ambulance!
Larry