• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

1981 CM400A Headlight Replacement

Micoviso

Member
Joined
Apr 17, 2021
Total Posts
49
Total likes
1
Location
Austintown, Ohio, USA
I’m not thrilled with the brightness of the original headlight on my bike. It looks like OEM replacements are available, but has anyone found a suitable LED replacement for the original sealed beam headlight that came with this bike or other CM400s? Original part number is…. [h=2]33120-333-670[/h]
 
I’m not thrilled with the brightness of the original headlight on my bike.

I haven’t tried LED’s, but I’m very happy with the H4 upgrade from 4into1.com on my CM450.
Do you still have your original glass tube style fuse block on your bike? Upgrading my fuse block made a big difference in lighting, also.


Tom - 1982 CM450E
 
How can changing my fuse block improve my lighting? Isn’t an electrical connection an electrical connection? I haven’t looked for the fuse block yet, but it’s a bone stock bike, so I don’t have any reason to suspect anyone would have changed the fuse block. Checking out 4into1.com.
 
^^^
The original style fuses are often replaced by similar type fuses purchased from auto parts stores which aren’t the exact correct size fuse. This can lead to bad connections and overheating which cause any number of electrical issues.
There are a few different threads here discussing it if you search. Here’s mine:

Headlight / Turn Signals not Working CM450E - FIXED!
https://r.tapatalk.com/shareLink/to...hread.php?t=3075&share_type=t&link_source=app

I had already replaced my headlight when I got around to upgrading the fuse block, but after I did all of my lights were brighter.


Tom - 1982 CM450E
 
How can changing my fuse block improve my lighting? Isn’t an electrical connection an electrical connection? I haven’t looked for the fuse block yet, but it’s a bone stock bike, so I don’t have any reason to suspect anyone would have changed the fuse block. Checking out 4into1.com.

It's about amperage delivery, any weak or poor connection in the circuit allows some lost power due to the resistance involved and the heat of a poor connection under load is how the incorrect fuses get hotter than originally intended and melt the fuse holder. A modern blade-type fuse block is the best way to go, then you're done messing with metric length glass fuses which are harder to come by here in the US.
 
I'm glad I caught this. I went to look at my own fuse box, and although it looks very good (I sprayed it out with DeOxit cleaner), I have two 15 amp fuses and one 7 amp. Looks like someone replaced the 7 amp headlight fuse with a 15 amp. Not good. I repair guitar amplifiers for a living, and I see this all the time. I will probably end up upgrading the fuse box, but for now I am putting the proper 7 amp AGC fuse in there.

Good catch!
 
I think the AGC fuse is too long, be sure it just fits the brass holders and doesn't project on either end. I think AGX is correct.
Both are 1/4" diameter AGC is 1.25"/31.75mm long AGX is 1"/25.4mm
 
…but for now I am putting the proper 7 amp AGC fuse in there.

Good catch!

Good catch, indeed!
Did you find a METRIC size glass tube 7A fuse? Mine came from the auto parts store (before I changed the fuse block), and it wasn’t long until I had lighting issues.

Edit: Just noticed LDR has this covered.


Tom - 1982 CM450E
 
AGC/AGX I am not sure. But the one I put in there is the same length as the rest of the standard size fuses I have in my fuse supply kit, as well as the same size of the three that were in the bike. I see no issues with this, it fits just fine. And the brass connectors are looking good, so I'm not concerned.
 
No worries, Randall, not trying to create issues; plenty seem to find us and our old bikes just fine! Cheers.


Tom - 1982 CM450E
 
EAE40087-77B4-4002-9A2F-A066E02817E8.jpg56857DFF-78CF-4D3F-ADFC-676724F41EEA.jpg2EF9559D-1CC8-4C41-B84C-83F9F0DDCA7D.jpg0B10F84C-800C-48C2-9093-DC594BB8E365.jpg

Looks like original fuse box, fuses, and cover, complete with spare fuses. I took them all out cleaned them, and sprayed some electronic cleaner, and re-installed. Then blew out with air to make sure everything is dry. The whole component looks brand new, and didn’t look much worse before I cleaned it. Considering the condition of this, do you guys think I should still change out the fuse box?
 
Last edited by a moderator:
With as clean as yours looks, I wouldn't change it, especially since you still have the protective fuse box cover. I doubt you'd see any improvement at this point.
 
Considering the condition of this, do you guys think I should still change out the fuse box?

Wow, that’s clean! Your fuses look like the correct size, and I don’t see any melted plastic near the brass fuse holders which indicates they are overheating.
Whether I think you should is just my opinion; I would because it’s one less thing to worry about, you mentioned wanting better lighting, and if you want to add any accessories (phone charger, etc) in the future you’re set. I’d put it in my list, but it’s not urgent from what I can see, and if you aren’t having issues.


Tom - 1982 CM450E
 
I'm a firm believer in "ain't broke don't fix" unless there's valid reason for doing so.
In this case the condition of your fuse block says leave it alone. Those are the correct length fuses, zero signs of prior damage, and very clean. The only thing I'll suggest is roll up some sand paper and polish the inside of the contacts, pinch closed when done and run with it.
 
Bike is on jack waiting for a rear tire. I am pretty sure the bike has the original headlight in it and it does light up, but not all that bright. Tom, I see you put a H4 upgrade in your bike, but 4 into 1 did not show the CB400T or the OEM part number for the headlight they offer. Looks like Partzilla has the OEM headlight plus the beam adjusting screw and related parts. I do like the idea of a brighter halogen light. And has anyone figured out the beam adjusting hardware?
 
Tom, I see you put a H4 upgrade in your bike, but 4 into 1 did not show the CB400T or the OEM part number for the headlight they offer.

For reference, this is what I have on my bike from 4-1. It was purchased and installed long before I was a member here and learned of the CB250 option from Jim. If you want the H4 halogen, AFAIK that’s probably as close to OEM as you can get with our bikes.

https://4into1.com/7-halogen-headlight-assembly-gloss-black/


Tom - 1982 CM450E
 
Thanks Tom, but I want to consider the 4 into 1 option a bit more. Reason is $$$. The CB250 option is around $140 with the beam adjustment hardware; whereas 4 into 1 is $55 for the light housing and bulb. I'm just not sure if it will be a direct fit into the CB400T headlight bucket. BTW, got my tire yesterday and installed this morning. The bike is off the jack. Believe it or not we got one inch of rain here in the high desert over the past 24 hours. So it's wet around edges here and a good day to work on bike details.
 
The CB250 headlight assembly is exactly the same as all of the CB/CM 400 models except for the lens/reflector, bulb and wiring cover. All the adjustment hardware just gets moved from old to new. Check MC salvage yards and fleabay
 
Thanks Tom, but I want to consider the 4 into 1 option a bit more. Reason is $$$. The CB250 option is around $140 with the beam adjustment hardware; whereas 4 into 1 is $55 for the light housing and bulb. I'm just not sure if it will be a direct fit into the CB400T headlight bucket.

4-1 has 2 sizes they sell; the link I shared is 7-3/4” ear to ear at the mounts, and the other they sell is 6-1/2” - just noticed this one it is out of stock. Don’t know what size you would need.
They both come with a metal headlight bucket; I swapped in the whole thing plug/play. I may have missed it earlier you were intending to re-use your original bucket, you could email 4-1 for specific dimensions. Or let me know what you need, I’ll take my lens off.
eae40201d1d78daccf32f760f1ce61ff.jpg

1a1ae18e446b3ca62fa74d119830aa4a.jpg



Tom - 1982 CM450E
 
You can also check out Common Motor Collective, they have these. I know from experience, I ordered the wrong size halogen bulb to fit in my original basket, and am waiting for the exchange to come back in stock. They are pretty knowledgeable about smaller vintage Hondas.
 
They are pretty knowledgeable about smaller vintage Hondas.

I don't think that's entirely true, they show plenty of falsehoods in their videos. They also tend to have higher pricing than most on many of the same things you can find elsewhere, but I will admit they offer a few things that others don't.
 
Last edited:
Tom, thanks for the great pics of your headlight and the front end of your bike. Here is a pic of my headlight bucket that was taken right after I acquired the bike. Also, my bike did not have the beam adjusting hardware with it. Looking at what's involved, it should be easily replicated with small items from the hardware store. I do want to keep the stock look for the bike. At this point, it is essentially as it was the day it was bought in Denver in 1979. Yesterday, I was able to get the rear wheel back on the bike and did a lot of detail work and I think it is ready for some longer test rides. I am going to table the new headlight decision for a few days, but the information has been great.
 

Attachments

  • Honda CB400T_17.jpg
    Honda CB400T_17.jpg
    103.9 KB · Views: 13
Any idea if the same H4 upgrade will work for the CM450's? My housing was cracked pretty bad and I'd like to remedy that. If I can update it to H4 at the same time that would be great I think.
 
Any idea if the same H4 upgrade will work for the CM450's? My housing was cracked pretty bad and I'd like to remedy that. If I can update it to H4 at the same time that would be great I think.
Yes, all the SOHC CB/CM 400/450 series use the same headlight bucket, lens, etc. with the exception of the 85/86 CB450SC. All have the same exact charging system so they will handle a 55/60w H4 bulb with no problems.
The easiest conversion is the CB250 (2001-07) headlight assembly which is the same as yours except the lens and replaceable bulb.
 
I am going to table the new headlight decision for a few days, but the information has been great.

You’re welcome, Denny. As far as I remember I saved my old/OEM headlight when I swapped, just have to find it. You’re welcome to it if I can find it, and if we’re lucky, it may still have the hardware? Maybe send me a reminder in a few days when you get back to it… good intentions vs. busy schedule. I didn’t realize until after the swap that the sealed beam was replaceable/available, but I’m happy with what I have now. (And it may have been my fuse issues all along… )
Enjoy your test rides… be safe!


Tom - 1982 CM450E
 
Yes, all the SOHC CB/CM 400/450 series use the same headlight bucket, lens, etc. with the exception of the 85/86 CB450SC. All have the same exact charging system so they will handle a 55/60w H4 bulb with no problems.
The easiest conversion is the CB250 (2001-07) headlight assembly which is the same as yours except the lens and replaceable bulb.

Thanks LDR!
 
This is what I went with….
https://www.ebay.com/itm/353553824912

it came with a new bucket, but I didn’t need it. The new headlight assembly fit perfectly in the old bucket. Simply plug and play, and now I have a very bright H4. The new assembly isn’t as heavy and solid as the original, and there is no horizontal adjustment screw like on the old one, but it isn’t needed. The price and shipping from Britain was more than I’d hoped, but it’s brand new and works great, so no regrets.
 
Continuing the story, since I now have an H4 setup, I removed the Halogen H4 bulb and replaced it with an inexpensive H4 LED that I already had. It’s advertised as being much brighter and clear light than Halogen. It’s definitely a much whiter light (different light temperatures, or colors are available), and possibly illuminates a little further down the road, but only on low beam. On high beam, the halogen does a much better job of lighting up further down the road. Looking at the bulbs, I suspect this has to do with the design of the elements inside the bulb. Maybe a more expensive LED would do a better job on High beam, but I’m thinking I might just put the halogen back in. It does a significantly better job than the original sealed beam light at both low and high beam, and when I turn on high beam, I like halgen’s performance better than the LED.
 
It's a common misconception that an LED will improve the headlight function when all it really does is provide a brighter light with no regards to focal lengths.
The filaments of a headlight bulb are specifically designed and set to take advantage of the convex reflector to focus the light in the lens correctly. This is all been researched and standardized through out the industry so all headlight bulbs have the exact focal length needed to work on every headlight reflector correctly.
LED's on the other hand are built in a long row and the placement is determined by the size of them. The physical constraints of size mean they will not be set for optimal positioning.
 
So tomeben - what H4 upgrade kit did you use, from 4into1? Did you have to modify it to fit?

I have two CM's badly in need of an upgrade from sealed beam.
 
So tomeben - what H4 upgrade kit did you use, from 4into1? Did you have to modify it to fit?

I have two CM's badly in need of an upgrade from sealed beam.

Tom hasn't been here in over a year, but this below in bold might be helpful

4into1 has 2 sizes they sell; the link I shared is 7-3/4” ear to ear at the mounts, and the other they sell is 6-1/2” - just noticed this one it is out of stock. Don’t know what size you would need.
They both come with a metal headlight bucket; I swapped in the whole thing plug/play. I may have missed it earlier you were intending to re-use your original bucket, you could email 4-1 for specific dimensions.
 
Not sure if Honda used the Nighthawk name in Canada but the CB250 from 2001-07 in the US has a replaceable H4 bulb system.
https://www.partzilla.com/catalog/honda/motorcycle/2003/cb250-ac-nighthawk/headlight-cb250-01-07

Yep - I'm aware of that option.
Headlight assemblies from CB250s are rarer than hen's teeth up here.
I see them being sold new/oem for as high as $300 USD. The used ones on ebay are usually in pretty rough shape.
So looking for alternatives.

I see the 6.5" Halogen upgrade on 4into1 has a reviewer who put one in their CM400 - with the use of a dremel. No additional details as to what part needed grinding, although I have to assume they took off 1/4 inch around the outer edge of the reflector to bring it down/closer to 6.25", the size of the original sealed beam.
 
Back
Top Bottom