I checked the lighting thread in the shop area and this has not been addressed.

Has anyone here put a larger headlight bulb (H4) into their stock HD headlamp assembly?

I am considering putting a 55/100 or a 100/130 bulb in the housing.

I guesstimate that this will add about a 4 amp pull to the electrical system. The alternator will easily handle this load but I am concerned about the actual headlight wiring and switch on the handlebars. Also, will the heat created by the larger bulb cause any problems with the headlight housing itself?


Thanks in advance. . .

 

If your looking for a brighter headlight call Howard @ Motorcycle metal. Heres the website >>> http://www.motorcyclemetal.com/index.html

He has a HID light kit that uses less voltage and is superior to any regular headlight bulb for brightness. I know... I have one of his kits

Let him know your a HD Forum member, hes very knowlegable and will help yah with any install issues you might have with his kit

 

I changed mine to a 85/100 Osram bulb last year, no problems as of yet, I also changed my spot to 37 watt from the factory 27's.

 

I wouldn't put the bigger bulb in. You will burn wires and switches eventually and may even destroy the headlight housing. If you want more light, go with an H.I.D. they only draw 35 watts but put out several times more light than your stock one.

 

I think there's 2 things to consider with a higher wattage bulb. The first is heat and the potential problems with your harness. The second is the legality issue. Most of those bulbs are legal for off road activity only in many states. While this may not be a major concern for you, it's likely that if you have an 80+ watt low beam there are going to be a lot of people flashing their brights at you thinking you're on high beam. That's going to get old after a while.
I know it's a little more expensive, but have you considered adding driving lights instead?

 

I run 2 65/70w H4 Osrams. Plus 2 55w H7 driving lights. I run my hi beams and driving lights during the day.
Like others said, you run the risk of wiring and housing related heat damage with high watt bulbs. Also, if you run big wattage like 80/100, your wires may not carry enough juice to give you all of the watts.

 

Good question. I've used 80/100w and 90/100w bulbs in my last two bikes for over 10 years without any problems. For the past seven years I've also used a Kisan modulator, which pulsates the high-beam at 20/100% 4X every second in daylight hours. This cools the bulb and reduces the amperage required and heat generated, not to mention making me more visible to oncoming drivers. I have heard of cases where the increased heat created by a high-powered bulb running a constant output will fry connectors, but I haven't had this problem on Harleys. A friend on a '98 Softail and another on a BMW GS had this problem, and their solution was to just change to a high-temperature connector purchased at Auto Zone.

As for the wiring on an FLH, I think you're covered. The stock low-beam circuit is designed for about 105w if you consider the passing lamps are wired directly into that wiring with no relay. HD doesn't publish wire gauge sizes, or at least I don't see it in my service manual, but the high-beam wiring is the same OD as low-beam. Thus, I can assume that it can handle a 100w bulb just as well as the low-beam does with 105w. I don't know how well the low-beam wiring could handle 80w while running the passing lamps, as that would add about 2A to the total. When I had my old RK I had some 37.5w passing lamps running with my 80w low-beam bulb that kept tripping the bike's 15A breaker. I installed a $5 automotive relay and never had another problem, as that took the load off that circuit and provided power directly from the battery.

With the modulator it's a better bet on high-beam because it will actually run cooler by modulating at 20/100%. There doesn't seem to be a longevity issue using the modulator either, as I've had the same bulb on this bike for over two years and on my previous bike several years before that. A good source for these bulbs is here. Go in with your friends and buy several and save on shipping. Hella is a good brand, and I've found them to have a long service life.

If you're looking for better light output you might also consider swapping the non-fluted HD headlights (lens and reflector) for some Euro-code lights. I bought a Hella E-code headlight from Susquahana Motorsports and the pattern is much better than stock on both low-beam and high-beam. High beam gives much longer "seeing distance," but the low-beams also have a superior pattern that have a sharp cut-off just under the eyes of on-coming drivers. I do not have any trouble with blinding or otherwise offending oncoming drivers on low-beams, as I never get flashed. For $35 you can't beat this for a lighting upgrade, especially in combo with the 80/100w bulbs ($8 ea.). The E-codes are legal in Europe but not in the U.S., but it is very doubtful anyone would hassle you about them. Anyway, few if any would know how to tell the difference, if it is discernible at all. Stock lights have a SAE designation, but so do the Hellas. These headlights have fluted lenses and aren't as cool-looking as the non-fluted stock HD lamps, but they do work better.

 

This is not a problem if the lights are aimed properly. I never have people flashing their lights at me while on low-beam. On high-beam (100w) that's another matter, but I don't do that purposefully.

 

Flyslow, Let me see and do a little math here. Ohms Law Amperes = Watts /Volts. Find it through Google. Now that you said “I am considering putting 55/100 or a 100/130 bulb in the housing”. So lets plug them in. Running your bike pulls around 12.8 ~ 14+ Volts depending on your bike. Lets take 13.5 V. 55W ÷ 13.5 V = 4.07 Amps. 100 ÷ 13.5 = 7.4 Amps. Also 130 W ÷ 13.5 V = 9.629 Amps.

Flyslow, You will not be called that for long as your headlight lamp (the glass thing w/silver reflector) will FryFast.

A little reading here should do the trick.
What Others Will Not tell you About Modifying your Lighting System PDF Download
How To: Aim Your Headlight, Relay Connections, & H-4 Plug Connections PDF Download

Just search the internet for all of the answers. Here are a few for you: H4 - 55/60, 55/100, 80/100, 80/130, 100/150 watt
Anything bigger than the 55/100 -100 H1 you must have relays or you will
fry the pins in the back of the fusebox. Note that only the stock strength are strictly legal.

A quote from the Iron Butt guys: I also know about Phillips Rally 100W, but they are not legal, and they end burning the headlight itself, darkening it, and because of that I have rejected the idea of trying one of those.

 

Not true for stock headlights. About six months ago I called North American Lighting, who make the headlights for Harley, and the engineer I spoke with said that a 100w bulb would not harm the reflector or other parts of their headlights. He said it might change the color of the backside of the light where the bulb mounts, but there should be no functional issues. He also said they had recieved no complaints from people running these bulbs. The E-code headlights are designed for this output since Hella (German) makes both the headlights and high-powered bulbs, and the use of high-powered bulbs in Europe is commonplace.

I would agree that it may be wise to keep 55/100w as the limit for bikes with passing lamps. Without any auxillary lights, like my SG with only a single headlight, you can run 80 or 90w low-beams with no problem. OTOH, on bikes with auxillaries you could always use a relay and that would solve any potential problems dealing with high amperage.