What is it?

[Lobo]

I don’t know the answer... nor does the owner of this 750K1. (He’s distracted by all his other toys... puts the street to shame with the fun stuff he has)

Anyhoo.

It looks like an indicator relay, and has been mounted under the tank / just aft of the coils. The leads disappear off into the headlamp shell.
Coincidentally there is a majorly big red lamp mounted between the Speedo / Rev counter. Related? Dunno.

With time I will indeed work out what this all is... but any suggestions in the interim?

Ta,
Simon

PS (1) It is not a replacement indicator relay. (2) have never seen the red lamp illuminated - ie not high beam nor anything repeater.

[Bryanj]

If it was a Japanese model it would be a speed warning

[Lobo]

...interesting Bryan; the red lamp is not a cheapo affair out of (ex) Tandy, and has a very profession / OEM installation look about it all.
That said, to the best of our knowledges (ie the owner too) the bike has always been an Oz import, ie not Japanese.

.... and would it explain the ‘indicator’ type canister, which conversely does not look original / installed in an odd place. (I’m suddenly wondering if it’s an attempt at some overheat light, esp as the bike lives in QLD.)

[SteveD CB500K0]

Any sort of overheat light would need a sensor somewhere. Can you follow the wiring?


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[Bryanj]

The canister looks like the unit shown in my japanese parts book for the 500(Ash put it Alladins cave i believe) but it needed a different speedo unit with extra wires comming out

[Lobo]

Hey Steve. Yea, the wiring simply runs from the canister up into the headlight shell. It’s not my bike, and with limited time, had other things to do other than satisfy my curiosities. Whether the big red lamp is part of the same circuit I can’t say (at this point).

Thanks Bryan... I rode the bike yesterday and was offended by the speedo mount being wonky. I straightened it... and in doing so didn’t not anything ‘abnormal’ about the instruments and their back-plates etc.

I will eventually figure this out as plan to renew the gaiters soon... and will have it back in my garage.

[K2-K6]

 Could be a shift light to come on at predetermined rpm.

As Bryan says,  maybe a speed limiter of sorts or warning to alert rider of maximum (I've heard they're pretty hot on speed there).

If no other input is visible,  some cars used a frequency signal from alternator output to read engine rpm which had no obvious feed to instruments,  just tapped into alternator with electronics to interpret signal rate.

[Nurse Julie]

On our 400/4's, we have a 'speed unit stay'. It's got nothing on it except it also doubles up as the hook for the big rubber band that hold the wiring loom in place down under the left side of the tank. On JDM model 400/4's (398cc) They had a sensor attached to this bracket, that some how picked up the speed the bike was doing and either made a light illuminate on the speedo clock or made a buzzer sound. It was all to do with speed restrictions in Japan. Many JDM bikes had it fitted as it was a compulsory thing on JDM bikes. How do I know all this useless info, well, we had exactly the same conversation on a FB site a couple of weeks ago 😁😁😁

[Lobo]

....well blow me... just found this on eBay.

It indeed looks like Bryan & Julie are on the right track; I’m bloody intrigued as to how it senses speed given it’s mounted just above the engine with no (obvious) input wires from anywhere. I need to read up on these units, as have no idea what speed they may be set to.... certainly it’s > 80kph as I didn’t trigger it when I rode it Fri.

... it’s a Goldwing part... and GW owners care to elaborate pls?

Ta.

[Bryanj]

Like i said before if it is the speed sensor, which normaly has the light in the chrome nut at top of steering stem, gave Ash one of those, there are extra wires from inside the speedo head, if you aint got those it wont work

[flatfour]

Japanese motorcycles and cars all had a speed warning light (and in cars a buzzer as well) fitted to them when I worked there in the 1980's. The one in the picture does look the same as those that I remember.

From memory (at least on a car) dealers could adjust the timing of the warning, presumably to account for any changes in the law?

[Seamus]

As above, definately a speed warning device. I worked on a japanese import several years ago and it had the lamp. Research at that time identified the beast.

[AshimotoK0]

As above, definately a speed warning device. I worked on a japanese import several years ago and it had the lamp. Research at that time identified the beast.

I have a CD250 JDM speedo/tacho combined ... same style as the CB72/CB450K0 unit and it has a little set of contacts inside that close when the needle/magnetic eddy current drum is up to Japanese speed limit. I also have that lamp NOS courtesy of BryanJ on here. I imported a CB175 wiring loom from Japan and it still had that canister attached. When I opened it up there was a little circuit board inside to take the speedo signal and drive the red lamp. I will probably fit it all to my 1969 JDM CB250SS.

[SteveD CB500K0]

Whatever was on the circuit board Ash? Late 60’s microelectronics? [very small valves?]


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[AshimotoK0]

Whatever was on the circuit board Ash? Late 60’s microelectronics? [very small valves?]


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I will dig it out and have a look .. seemed quite modern on PCB .. I guess it was circa 1970/71.