Topic: '72 CB500 JDM Speed Warning Light

[Dr. Frankenstein]

I'm rewiring my 1972 JDM (Japanese Domestic Market) CB500 Four and it has a speed warning light mounted in the neck. I'm pretty sure I have everything connected correctly, but there is a male brown/red wire and a male black wire coming off of it that I'm not sure where it goes. I have the correct wiring diagram for a CB500K, but I'm not seeing a brown/red wire connection anywhere.

The only connection I have in the headlight bucket that is Brown is a single female connector that I believe fits the brown male connector that goes to the little light that (for some reason) is mounted in the headlight that you can see in the pic. Any idea where that Brown/Red wire for the speed warning light goes? (And yes, I've repaired all those open wires).

[HondaMan]

You might not have the little module that makes the light go ON at 50 MPH (or thereabouts). I have a JDM-equipped CB450 in the garage, will try to take some pix later today.

[Dr. Frankenstein]

Ah! That could be! I took a lot of pictures, but don't remember it being attached to anything...truth be told, this bike was in pretty rough shape electrical-wise...I'm pretty sure the wiring under the seat isn't supposed to be like this...! HM, you don't happen to have a 500/4 JDM wiring diagram, do you...? And what's the function of the little light in the headlight?

[bryanj]

The little bulb is a "sidelight" and is a requirement in some countries, should also turn on with rear light when ignition key is in th P(ark) position, also a requirement in some countries.
The unit to make the speed light work i think is by the coils and the speedo has extra wires to make it work

[Dr. Frankenstein]

Doing a little research, the interwebs say the SWL trigger mechanism is in the speedometer - "Trigger Mechanism: The light is typically triggered by a mechanical disc located inside the speedometer gauge (the "clock")."  Is this accurate? Maybe that's why I didn't find some sort of 'unit' or whatever on the bike...I still don't know where to plug in the connector in the bucket though, I can't find a similarly colored female connector.

Anybody know where to get a JDM wiring diagram...?

I also found this about that little headlight side light: "JDM/European Specification: It is often referred to as a "pilot lamp" in technical manuals and is characteristic of Japanese or European market bikes, where it was required for riding in city traffic without using the full headlight." Interesting....

[bryanj]

If you go to sohc.co.uk you will find in alladins cave an early japanese parts book where you will find there is an electrical unit which the speedo triggers to put the light on.
There is a quirk in UK law where you have to have an " obligatory" light if lights are fitted(side/parking/pilot light) but headlamps are optional BUTMUST WORK PROPERLY IF FITTED

[Dr. Frankenstein]

Bryan, would that be in the "CB500 K0 Parts Manual (March 1971)" section, courtesy of you?  Which section in the library?

[kyle750]

Following this thread with great interest   Here is a photo of my CB550 JDM overspeed warning light.  Unfortunately it will be a long time until I can get to looking at the wiring on the bike.

[kyle750]

A quick followup.  Yamiya sells the small overspeed metal warning stickers in Japanese Kanji.  Rectangular for the CB550 and curved for the CB750.  I see your bike still has the original sticker 

https://yamiya750.com/products/ca013

[Dr. Frankenstein]

Hi Kyle - yup, mine looks exactly like yours - but how is it hooked up? Where does the connector in the headlight go?  Also, it looks like Yamiya only has the curved warning sticker, that won't fit on my steeringhead.

[kyle750]

Hi Kyle - yup, mine looks exactly like yours - but how is it hooked up? Where does the connector in the headlight go?

IIRC we visually traced the wires coming from the bottom on the neck to a relay in the headlight bucket that looks like a toasted marshmallow.  I have not tested the wires so I really don't know if this is the correct path. 

[Dr. Frankenstein]

Oh Yeah...! I have one of those in my parts box, I believe - I think it was hanging when I go the bike...I thought it was one of those stupid directional buzzers...does yours look like that/those?  Does it make a noise when it hits its 'speed', do you know...?

[kyle750]

On my CB750 the overspeed warning relay (also looks like a toasted marshmallow)  is attached under the tank right behind the ignition coils. We tested the wiring and tiny light bulb on the CB750 and it works  .  Bulb has a removable plastic housing attached under the top triple tree.   But we were unable to test the switch inside the speedometer gauge to see if it actually switches on when the set speed is reached. As my good friend Tony said "Who cares . . . you're never going to ride the bike over 80 km per hour"    

[Dr. Frankenstein]

This is the one I have in my parts box - it looks and sounds like a (rather sickly!) turn signal buzzer, and the wires in the bucket match up to this part, so I'm assuming that's it...it emits this really sickly feeble 'screech' when I tested it on a battery...but I'm assuming it mounts somewhere on the frame maybe, because of the tab on it...?  I'm pretty sure I don't have that frame mount; I didn't see anything like that when I disassembled the bike...how do you have the wires run from the outlet on the neck into the bucket? The wiring for mine is currently in the bucket - it comes out the bottom of the neck and then loops up into the headlight bucket...is there a better route?

[newday777]

This is the one I have in my parts box - it looks and sounds like a (rather sickly!) turn signal buzzer, and the wires in the bucket match up to this part, so I'm assuming that's it...it emits this really sickly feeble 'screech' when I tested it on a battery...but I'm assuming it mounts somewhere on the frame maybe, because of the tab on it...?  I'm pretty sure I don't have that frame mount; I didn't see anything like that when I disassembled the bike...how do you have the wires run from the outlet on the neck into the bucket? The wiring for mine is currently in the bucket - it comes out the bottom of the neck and then loops up into the headlight bucket...is there a better route?

That is the Turn Signal Buzzer, not the SWI relay
It mounts on a tab behind and part of the hand headlight ears, that has a square hole in it.

[Dr. Frankenstein]

You are Correct Sir! I was doing some more digging and came across this, frame mount and all - not sure if it works, or how to test it - is this it?? Where does this mount, under the frame?

[HondaMan]

That looks vaguely like the ones I saw in old Suzukis (1970s era bikes, but their modules were more rectangular than round) when I had my shop: one being in a Hustler 250 (I forget what the 2nd one was...) that a serviceman brought back with him from Japan, and was going to the college in that town. He wanted it removed as the new US law for "headlights on always" was draining the battery and this gizmo wasn't needed here, he was hoping to save some battery power by having us remove it.

I took the headlight open on the domestic 450 in my garage and discovered the red light's wires plugged into the Blue HI BEAM circuit for the headlight! There is no module inside the headlight. It has the Blue HI Beam indicator in the USA speedometer, and the red warning light comes on at the same time. The speedo is in MPH, so I suspect it is not the OEM speedo. That makes some sense to me, as the chains and rear sprocket are not OEM parts, while the speedometer has low miles on it. I think this 450 may have once been a domestic bike, but has been reworked: it still has the Mecum license plate on it from the recent auction. I don't think the new owner knows the red light doesn't work right.

[MauiK3]

My SEV Marchal headlight (from Yamiya) has the little light that comes on with ignition.

Like this:https://yamiya750.com/en/products/l074c

[Dr. Frankenstein]

I have a feeling this bike was rode hard and just 'put up' by the PO; I've had to re-splice, insulate and put on new bullet connectors on so many wires on this thing, not to mention getting rid of that industrial-grade cabling that (I assume) was just patched in to fix whatever problem the PO had in the rear. It threw me a curve too with the rear taillight mounts, which actually belong on a CB450 or 750! I used some washers to mount them and 'made it work', so to speak (they're the ones that came with the bike), and I have tested all the lights and horn, and they all work now too, so that's some good news...now it just comes down to getting the wiring sorted, which I think I have, I just have to route it correctly. All things being equal, where is the mount for the speed warning mechanism supposed to be located?

Plus, I think the headlight ears might not be the right ones either - Newday, I'm not seeing a square hole on them, maybe I'm just blind - wouldn't surprise me...

There's more shady stuff with the turning radius too - it turns more freely to the left than it does the right - it looks like somebody broke off and re-welded the little right-side turn-stud/stop that's mounted on the lower neck...not sure yet what I'm going to do about that. Lean into the curve more, maybe...?  I'll try to make a video of that later.

[bryanj]

I have screenshot several pages of the jdm parts book, if you want it all go to sohc.co.uk and look in Ashs dropbox, all part numbers are there but descriptions in Japanese

[bryanj]

Next one

[bryanj]

As shown the unit is under the tank near coils