Brighter headlight bulb?

e3steve · Post by **e3steve** » Sat Aug 01, 2009 8:35 am

carlluvscorinne wrote:Hi Jensen:

Thanks for the info, my reflector appears to be in great shape, crystal clear with no hazing or scratches. So just a new rectifer, CB400F reflector with an H4 bulb. I can use my original trim ring, headlight bucket and tail light bulb?
Thanks in advance, Carl

Carl mate, your (our) charging system(s) will not, I believe, support a 55/60W H4 headlight bulb without surgery involving the replacement of your stator; there's a Rick's Motorsport http://www.ricksmotorsportelectrics.com ... da_kit.pdf conversion. I also understand that it's possible to fit a Bosch stator from a BMW K75(?); perhaps a forumer more knowledgeable can confirm, but I have read that it's a simple transplant.

Let's do the maths:

My charging improvements have achieved, @ 4000rpm, : 13.65V / 3.0A, parking light on*, so this result is following the replacement of the rectifier (Schottky-diode) and the taillight bulb (LED).
Ideal charging voltage for a 12V system is 13.8V, so 13.65V is less than ideal, if satisfactory, in practice.
So we have 3 Amps of headroom which, at 4000rpm and 13.65V, equates to peak support of 40.95 Watts; this doesn't take into account starter usage, times of riding at, say, 3000rpm, etc..

Now, the exact science applied here won't be definitive, owing to variables such as poor connections, differences in stator windings' impedances, etc., but it will be pretty close. All that said, you might just get away with a 50W headlamp bulb along with the use of a battery-tender. My CB survives with no external charging but with all the improvements that I've tried (with success) and a 7Ah battery, winkers, compact air horns, but still with a 35/35W (halogen) headlamp bulb and LED taillight. Bear in mind that if you do aim high for the 55/60W H4, then be prepared to externally support the battery with a tender and / or replace the on-board charging system.

* Using the lightswitch in the 'headlight' position / dimmer switch centred; not advisable in some US states where the mid-position provides both hi- and lo-beams together.

Vince Lupo · Post by **Vince Lupo** » Sun Aug 02, 2009 11:01 am

I've just had my low beam filament in my sealed beam unit break for the third time this year. All my grounds are good, and my mechanic even installed an extra ground dedicated to the headlight. It's probably vibration, as the 1000+ mile ride to and from Mid-Ohio last week more than likely caused it.

In any case, I'm looking to convert my sealed beam unit to a replaceable bulb system. Any idea how I can go about doing that? As well, can I still retain a 35/25 watt bulb?

e3steve · Post by **e3steve** » Sun Aug 02, 2009 12:30 pm

Vince, keep an eye out on eBay for a replaceable-lamp beam unit. Few & far-between, but I've seen them. I watch, most days, for new listings; I'll keep an eye out on your behalf. There is little market-defined difference, if any, in the glass; the beam pattern in my UK-market beam unit is symmetrical. If you get one with a Euro fitting, the Bosch BA20d 35/35W halogen lamps are easily available from Goffy.

Mine has lasted all last season and so far this season, even though my instrument lamps have popped due to vibration.

Vince Lupo · Post by **Vince Lupo** » Sun Aug 02, 2009 1:29 pm

Great -- thank you for the info and for keeping a lookout for me. I've installed three headlights this year (all new old stock) and all the low beams go within about two months.

So what I'm looking for is specifically for CB72/CB77, as far as that replaceable bulb headlight unit goes? Fortunately, I do have the three-prong plug setup, so at least that part is done!

jensen · Post by **jensen** » Sun Aug 02, 2009 3:23 pm

Steve / carl,

Before I experimented with a H4 bulb I measured also the currents @ different rpm's.
I measured more than 4.3 amp above 4000 rpm, that's why I by experiment replaced it with a aftermarket H4 unit from a cb400f (I own one). Actuale I drove with it a few months, and above 4000 / 5000 rpm it gave much more light that a 35 / 35 W bulb. Because I replaced the H4 unit of my CB400f with a xenon system and was very pleased with the results, I changed the system of my cb72 also to xenon. I have to say that I have a new NOS rotor installed before the measurement.

Jensen

e3steve · Post by **e3steve** » Sun Aug 02, 2009 3:38 pm

jensen wrote:Steve / carl,

Before I experimented with a H4 bulb I measured also the currents @ different rpm's.
I measured more than 4.3 amp above 4000 rpm, that's why I by experiment replaced it with a aftermarket H4 unit from a cb400f (I own one). Actuale I drove with it a few months, and above 4000 / 5000 rpm it gave much more light that a 35 / 35 W bulb. Because I replaced the H4 unit of my CB400f with a xenon system and was very pleased with the results, I changed the system of my cb72 also to xenon. I have to say that I have a new NOS rotor installed before the measurement.

Jensen

Thanks for the info, Jensen. You're a lucky chap; you must have the high-output rotor which, I seem to recall, was fitted to some markets' C / CA77s. I've been looking for one since I acquired CB! Did you get it from CMS?

e3steve · Post by **e3steve** » Sun Aug 02, 2009 4:32 pm

Vince Lupo wrote:Great -- thank you for the info and for keeping a lookout for me. I've installed three headlights this year (all new old stock) and all the low beams go within about two months.

So what I'm looking for is specifically for CB72/CB77, as far as that replaceable bulb headlight unit goes? Fortunately, I do have the three-prong plug setup, so at least that part is done!

Thanks to the info from Jensen, I'm now on the lookout for an AM beam unit for a CB400f, which may just be the same as the CB250N & CB400 Super Dreams. I'll keep the forum info'd as to whether this is the case.

FYI, our CBs employ a 16cm beam unit; it should be borne in mind that the Japanese worked to the metric system of measurement, as does most of the rest of the world now........... except North America! And marine & aviation distance / speed. And UK road distance / speed! Which is different from the US!! Doooohh.......

I digress. The 3-prong lamp attachment is specific to the sealed beam and certainly differs from the 3-wire connections for the European fitting. A simple change is required to 3.9mm bullet receptacles & insulators, freely available from http://www.vehicle-wiring-products.eu/V ... ullets.php . The H4 lamp's 3-prong attachment uses larger blades than the 6.3mm of the older sealed beams.