6 Volt Lightbulbs

[hennesse]

I wonder if we could put together a list of the lampbulbs used on Ks and early XLs.

What got me started on this: I needed both headlight and taillight bulbs for my '62 CH. But none of the bulbs I could find quite matched what was in the 1959 Service Manual (see attachment).

The trade 1158 taillamp bulb appears to be a 17/5 watt, which is somewhat close to the Harley 68165-47's 21/3 watt.

The trade 4020 headlamp is a 30/30 Watt, which is nowhere close to the Harley 67717-59's 40/35 Watts.
The trade 4031 headlamp is a 45/35 Watt, which is closer to the Harley 67717-59's 40/35 Watts.
The 4031 is also close to the Big Twin and Servi-car 67717-48A 50/40 Watts.

What the heck were the originals? Were there really a bunch of light bulbs that are just totally unavailable now, and things like the 1158 and 4020 the only ones still produced?

Both modern and NOS 4020's are fairly cheap. The 4031, when you can find them, are really expensive. The only other thing they seem to fit is really early Army Jeeps. But they're pretty close to the original wattage, which might come in handy when that deer steps into your path late at night. Of course, most of us don't ride our antiques late at night, but it might come in handy.

Can you shed any light (pun intended) on the 6v bulbs used on these bikes ???

Dave

[John R]

Hi Dave

You're mixing C.P. (candlepower) and watts, and there's no fixed relationship between them, only approximate. Candlepower is the amount of light produced and it's measurement has been redefined many times over the years, starting by comparing a light source against, yes, special precision candles! This is how the first carbon filament bulbs were judged. There are more modern measurements now, lumens often being specified.

Watts is the amount of power used. Conventional tungsten filament bulbs of same wattage can appear different brightness, and that's ignoring all the fancy modern types - halogen, LED, etc.

With old incandescent tungsten filament bulbs of lower power it used to be approximately 1 C.P. = 3/4 watt so a 20 C.P. bulb would be about 15 watts, but this varied from manufacturer to manufacturer. Only C.P. rated old stock will be a close match as modern bulbs are made to be brighter than old ones. They take advantage of the increasing power output of improved automotive generators over the years. Using a 21/5 watt tail/stoplight will be safer and won't overload the system as maybe much higher wattage headlamps might do.

The old low output bulbs such as 3 C.P. can look uncomfortably close to just that - 3 candles!

John

[hennesse]

John,

I was putting together this web page http://www.harleykmodel.com/technical/lamps/index.html
and after awhile, my brain got really confoozled by all those different numbers.

The idea is to try and figure out two things - what the original bulbs were, and what replacements are available today. For example, I don't know what exactly the original K 30w/30w headlights were, but 50w/40w 6006 lamps are cheap and plentiful, and I suspect that's what most people use, even though they have a much higher rating than the original.

We do have people in the group with original or semi-original bikes - look at your bulbs - either on the bike, or those NOS ones on the shelf, and let me know what goes where, so I can update this page. What's on your bike or shelf?

My 54KH has a 6006 sealed beam - obvious replacement. The Gen and Oil lamps are GE 55, and I'll bet they're original. My 62 CH has a replacement 4020, and the only other bulb on it is the taillight. The previous owner had modified a straight-across pins 1158 to fit in the "indexed pin socket" - it should have been an 1154 -so no help there.

Note: there are no links to the page right now (it's an "orphan"), since it's too rough for publication. Hopefully folks can corroborate or correct what I've written so far, and we can move it into production soon.

The old low output bulbs such as 3 C.P. can look uncomfortably close to just that - 3 candles!

As I noted on the page - I think H-D's C.P. ratings for the dashboard bulbs are wrong - by a factor of 10! The tungsten elements of all these bulbs are pretty much the same. How can the tiny element in a 55 produce the same amount of light (and heat) as the much larger tail lamp element in the 1154? I don't think so.

Dave

[John R]

Hi Dave

K bulbs

The original K Model sealed beam 67717-48 was 30/30w and was a Guide unit. There's still a GE unit available GE6006 also 30/30w as fitted to your '54 KH.

The #55 bulbs don't show a rating but pull .36a at 6v which calculates to 2.23w, equivalent to 3c.p. (at approx. 1c.p.=.75w). Harley specify 68462-49 for the warning lights and state 2c.p. - I think Harley weren't that fussed!

The original fitment stop/tail was 68165-47 at 21/3c.p. The nearest new stock is a 1154 at 18/3w (about 24/4c.p.) but I would use a 21/5w for safety.

You can have two different looking filaments of the same light output or wattage. You can have a longer thicker filament doing the same as a shorter thinner one. I have put two different filament 3 c.p. bulbs next to each other and they look the same brightness, but hard to judge exactly - they both pulled .4a within a smidgen.

From the first electric lit Harleys through to the 60s tail lamps were 3c.p. - not as bright as the 1154 closest modern replacement. They didn't believe in overloading the electrics!

John

[John R]

Hi Dave

More bulb stuff! I looked through my bulbs to try to show that the watts of a bulb does not necessarily indicate how bright it is. The first picture shows the bulbs in close-up to show they're both marked 6v 3w. In second picture if you look closely the right bulb's filament is more coils of a heavier wire (heavier tungsten wire has less resistance for a given length, so a greater length is required for the same resistance as thinner wire).

When lit, the heavier wire one is much less bright BUT puts out much more heat - it's too hot to hold between fingers, but the bright one no problem. Interestingly the dull one pulled .57amps at 6.2v, the bright one .41amps - calculates to 3.5w and 2.5w respectively - both off the nominal 3w.

So the higher wattage bulb is much dimmer - however it's also tougher being much less prone to vibration failure. Because old bikes vibrated and shook more the bulbs needed to be tougher.

Bulbs of the same candlepower (designated cp or just c) should look same brightness whatever.

Finally I checked both 4031 and 6006 sealed beams. Surprise, they both check to 45/35watts within a smidgen.

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[John R]

I started looking around for replacement 6 volt sealed beams for Ks and Sporties and this is what I found.

67717-48 7" 6v 30w/30w '52 to '58 - no readily available exact match**. Trade 4030 is 6v 45w/35w. GE6006 claims 6v 50w/40w but measures a bit lower. I've been using the GE6006 for years without any bad effects except if you're stuck in slow moving traffic for an hour or more the battery will get low - open road, no problem. However, these are a close match for 48-64 Big Twins and Servi-Cars which used 67717-48A rated 6v 50w/40w

67717-59 5.75" 6v 45w/35w - Trade 4031 is a dead match and 4067 close at 50w/35w. Trade 4020 are only 30w/30w. All seem readily available.

**At http://www.jirehcycles.com they list the GE6006 as 6v 30w/30w and a replacement for 67717-48 but I guess this incorrect - everywhere else GE6006 are listed 6v 50w/40w.

John R

[Mayday53]

I saw a halogen 6v lamp headlamp on EBay...it has a removable element assembly. Any thoughts about this?

http://www.ebay.com/itm/like/2310234612 ... =82&chn=ps