Topic: Will my charging system handle H4?

[onetruepunk87]

I've got a '77 CB750K, I've been running a new headlight on it with a 35/35w H4 bulb. I do half my riding at night, coming home from work, and want to have as bright a headlight as possible. Would a 55/65w bulb be to much a strain on my charging system? I upgraded to H4 on my previous bike, a '79 CM400, but was forced to use a lower watt bulb because it started to fry the wiring in my headlight bucket.

[HondaMan]

I've got a '77 CB750K, I've been running a new headlight on it with a 35/35w H4 bulb. I do half my riding at night, coming home from work, and want to have as bright a headlight as possible. Would a 55/65w bulb be to much a strain on my charging system? I upgraded to H4 on my previous bike, a '79 CM400, but was forced to use a lower watt bulb because it started to fry the wiring in my headlight bucket.

The alternator will support it, but a few other things might need some attention to keep it reliable.

First: the fuseblock probably has lost the chromate coating on the fuseclips, which will now make it heat up your fuses. This makes them melt, simulating blown fuses. It also lowers power across the whole bike by wasting it as heat. So, you can either polish those clips back up with a brass brush (.22 caliber gun bore cleaning brush is a perfect fit) and add a drop of oil, or I can make a blade-style fuseholder for you so you can use modern automotive fuses instead. PM me for that, it you're interested.

Next: the Start button provides power to the headlight when it is not pressed. This is how it goes out when you press it to start. But...the contacts in those switches are rated for no more than 55 watts, and they slowly melt when used with halogen bulbs over that wattage. I also make a Start Button Saver Relay kit to solve that problem, same comment about the PM if you're interested.

[crazypj]

I've used them, but, I always fit relays as I've seen way too many people burn out switches

[onetruepunk87]

Thanks for the quick responses. I just might take you up on one or both of the kits, Hondaman. I'll PM you once I have some more cash to put into the bike.

[drj434343]

Alternate recommendation, especially if you do half of your driving at night.  Consider investing in a LED headlight.  The Truck-lite 27270 is down to $190.  Pure white, HID quality light with good cutoff, and only uses 21 W low beam, 43 W high beam.   I recently made this investment in my CB500 after considering the costs of retrofitting other things for running an H4 safely, and am glad I did.  The LED puts out much more light than an H4 ever could.

[Dave-and-his-550]

The LED conversion sounds like a sweet idea, and judging by the pictures I've seen of that particular brand, it plugs right in, correct? Without any other modifications to the system? I'd love to have something like that for my CB550 as the headlight on my bike really seems to have poor output to the point where I don't dare riding out in the country at night until I fix it up. Here is some info on the truck-lite LED light

Truck-Lite 27270

[drj434343]

Here are some quick pictures on my 500.  It does fit perfectly into the bucket, including the ability to use all stock tabs that would normally be on a bulb.  It also plugs directly into the harness with the standard 3 prong plug.  No ballast box or anything messy.  Additional benefit is that there is no noticeable change in output brightness at idle versus higher RPM like with a normal bulb.

Two things to note, the bulb depth is the same in terms of intrusion into the bucket so there are no wire fitment issues, but it does stick out in front of the mount about 3/4" further than a standard sealed bulb.  It allows a narrow black ring to be visible forward of the chrome bucket surround.  Additionally, as you can see, the front of the light has a much different look than stock, which gives the front of the bike a non OEM look.  For me the gain in functionality far outweighed the changes in look.  Not only do I get much more light, I also get back 3 amps!

[Black 750K8]

I've got a 55/60 watt H4 in my 77 CB750 and it works fine. Put one in my brothers 77 and it also works fine. I used a Bosch H4 reflector and have tried others with similar improvement results.

Anything above 2000 rpm feeds alternator power to the battery, so basically it's always running off the alternator when riding except at idle at a stop light. It's very close to the stock value for electrical draw so this is to be expected.

The light quality is much better than an older type halogen 60 watt sealed beam which I used for years.

I did have an issue with my fuse box when I got the bike several years ago running an OEM sealed beam. The PO used the wrong length fuses which had reduced electrical contact which  heated the fuse connections. Once I cleaned the fuse holder contacts and employed the proper length fuses it has been fine to date, although I do check it every season for condition.

You could run a fused wire to the headlight bucket/area or near the coils, then plug the headlight wires into a cheap automotive type/use headlight relay and from the relay to a much bigger H4. I tried the HID thing in a conventional reflector and as bright as it was it sucked big time for lighting the road properly.You could get the HM stuff also for an easier go by letting someone else figure it out for you.

rt

roto What about the heat inside the bucket any thing to be concerned about?

[onetruepunk87]

Thanks for all of the LED info, something else I can look into.

[bjbuchanan]

I'm running an h4 too, the additional heat, if any isn't a concern. If something melts it is probably due to crappy connections not the actual light

[Pecantree]

The PO had put an H4 in a couple years before I got the bike. Both items Hondaman mentioned were things I had to do to mine. Plus the relay hack. Things are good now.
Would also recommend cleaning and lubing all the bullit connectors. That is a labor of love. Took me a full day to do.

Dave and Dj: will have to explore the LED option for my 360. The old lamps is just too dim. Scary to ride at nite.

Steve

[onetruepunk87]

Yea, I went through all the bullets a couple months back as well as cleaned the fuse connectors to stop my main fuse from blowing.

[robvangulik]

In Europe the K7 and F2 were standard equipped with H4, as was the CB550 from '78 onward...

[Wobbly]

Actually, the 77 K7 came from the factory with H4 lights. The European model would use a 60/55 W H4 light bulb while the U.S. model would use a sealed unit.

[Wobbly]

In Europe the K7 and F2 were standard equipped with H4, as was the CB550 from '78 onward...

You beat me to it.

[robvangulik]

I put a f2 unit in my 750F1 and rode it for 13 years and more than 200.000km without a problem (and without relay), so whats the fuss about.

[crazypj]

You could always get a 35w HID, although the ballast is a bit bulky

[Don R]

If you have good perfect original switches it's all good but the replacement ones aren't so great and the originals are over 35 years old. That's why you may need a relay.

[Tremelune]

I mulled this over a few months ago. It looks like you can spend $100 on pretty good lighting or $250 on killer lighting.

http://www.bayarearidersforum.com/forums/showthread.php?t=431847

I believe modern LEDs are worth it for the light output and reduced draw on our already-weak electrical systems.