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Post by Rossco on Nov 7, 2023 6:49:44 GMT
CB400N tuning out to be more of a Mongrel than I'd anticipated. In trying to remedy my wildly jumping instrument needles (yep both of them) I must have knocked a broken wire or caused a short or something. No spark. Boo. It's lead to finally fixing the ignition barrel that takes the same key as my fuel cap lock, so that's a win. Oh and I found an original flasher can in my box of bits so the yucky cheap modern one goes in the on-board spares compartment. Huzzah! Now that I'm going through all of my wiring, tidying up in search of answers I find myself paying more attention to these few oddities: There's a relay/cap/circuit/thermal something tucked-up under the fork bridge that I've never seen on a bike before. Four wires. ![]()   Also, the stem nut features this little red light which I'd been ignoring until necessary (now).   ..and finally, the speedometer has this little sensor dial of two different metals which are detected by a three-wire sensor that sends two wires back behind the headlight where it interacts with the other two oddities just mentioned.  These aren't detailed in any parts fiche I've seen or in my Haynes manual. Has anyone seen this before?? As far as I can tell they don't communicate with anything outside of the parts listed above. The system draws earth from the headlight and power from a black wire in one of the connectors, assuming from the rectifier. It appears to be wired as such that the speedo sends to the mystery part who uses that signal to decide whether or not the indicator light should be allowed a path to earth. I'm baffled. |
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Post by buster on Nov 7, 2023 12:51:10 GMT
has someone fitted an electronic speedo to it?
there would be a pick up somewhere, probably at the other end of that relay thingy wiring
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Post by BritPete on Nov 7, 2023 13:10:50 GMT
has someone fitted an electronic speedo to it? there would be a pick up somewhere, probably at the other end of that relay thingy wiring I think you may be correct  |
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Post by Rossco on Nov 7, 2023 21:37:21 GMT
has someone fitted an electronic speedo to it? there would be a pick up somewhere, probably at the other end of that relay thingy wiring Hey Buster thanks for contributing:) I cant say for sure that this hasn't happened, but as far as I can tell, no. No pickups either. There are only enough wires to connect the components listed, no 'loose ends'. The four wires to the relay thingy are power, earth, sensor, light. Also the Era-appropriate speedo is a major part of this setup -- the disc and sensor inside give every indication they were part of the factory design -- there's a hole for the wiring and even a lug to hold the cable in place cast into the body.  BUT I can't for the life of me find a photo or a description of such a speedo. One clue is that the gap in the sensor disc suggests three levels of detection: Under 70 km/h 70 km/h Over 70 km/h My first theories were based around the low speed / high speed timing coils within the stator/generator but there is no interaction with the rest of the electrical system. And if it was required you'd all have these speedo and mystery part. So.. nah. Being Nippon Seiki but not searchable under the Honda 400s I can only hazard a guess its a stock speedo of a similar bike from another manufacturer? Same top speed and design. For whom else were Nippon producing these teal-backed instruments for at the time, anyone? Big clue I'd missed:400n - all speed increment lines are white This one - over 80 are orange  Back to Google I go. |
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Post by buster on Nov 7, 2023 22:27:01 GMT
can we have a pic of the back of that speedo please?
the only wiring on a standard speedo is for the back light, the speedo itself is manually driven by cable from the front wheel
an electronic set up wouldnt be driven by the ignition system, it would have to be something that relates directly to the speed that the bikes travelling, a pick up could be on either wheel (likely) or possibly the front sprocket
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Post by Rossco on Nov 7, 2023 22:51:04 GMT
can we have a pic of the back of that speedo please? Buster the previous post shows the rear of the speedo, you can see the hole where the bulb inserts and next to it the hole and cable for the 'sensor'. The original post shows the sensor mechanism inside which is purely mechanical. You're right, it's not an "electronic" speedo. The needle mechanism is identical to our other stock 400n instruments aside from this additional 'detector' disc. I've found a few leads and investigated the suggested makes and models but have yet to turn up an appropriate wiring diagram or parts fiche . link
Allegedly many of Suzuki's 2-stroke trail bikes of the same Era had the red markings over 80km/h and the pink and green wires. But so far I haven't solved this puzzle. |
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Post by Rossco on Nov 7, 2023 23:02:49 GMT
  400n speedo vs Mystery speedo |
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Post by Rossco on Nov 7, 2023 23:12:46 GMT
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Post by johnfcbn44dx on Nov 8, 2023 1:09:13 GMT
But what does the red button do...   |
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Post by Rossco on Nov 8, 2023 1:50:22 GMT
But what does the red button do... Brilliant, thankyou John. At least now I know the origin of the light assy. ..and why it fits so perfectly  Not a lot of resources searchable for the 400D How did you come across that diagram John? Seems to me cmsnl and honda-parts both have incorrect generic 400n catalogue for this model The instrument in your photo certainly seems to be orange on the right-half.. Starting to unravel: linkJust really want to see the correct part numbers. I actually wonder as the "speed warning light" is a purely Japanese market phenomenon, perhaps my first-run jap model (is a '78 jap import) may have arrived stock with these parts. |
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Post by buster on Nov 8, 2023 6:49:54 GMT
well spotted john
so is it just a 50mph warning light on the top yoke nut?
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Post by Rossco on Nov 8, 2023 7:59:45 GMT
well spotted john so is it just a 50mph warning light on the top yoke nut? Yep. 85km/h as per Jap road limits of the time.. Confirmed in this Hawk II brochure I managed to dig up (pdf too large to attach, screenshots below) Wiring as per my system, inside the can is a little circuit board. Thanks John for sending me in the right direction. Swapped a bulb into that holder, here's hoping it all still works. Lamp wiring tidied up, new plugs, got her turning over as well as ever. Main thing I have left to do now is sort a combiner box as previous owners have welded pipe onto the silences and jammed them straight into the header pipes.   |
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Post by buster on Nov 8, 2023 10:39:53 GMT
your japanese is clearly better than mine  |
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Post by CTB on Nov 8, 2023 19:15:53 GMT
I have a Japan market Cx500 custom known as a GL500 in Japan. When I first rode it I thought I had low oil pressure as this red light came on, then I realised no I have an oil light so is it charging failure light? I did all checks and the charging system was fine. I finally decided to use modern technology and …….   |
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Post by johnfcbn44dx on Nov 8, 2023 20:34:15 GMT
But what does the red button do... Brilliant, thankyou John. At least now I know the origin of the light assy. ..and why it fits so perfectly Not a lot of resources searchable for the 400D How did you come across that diagram John? Seems to me cmsnl and honda-parts both have incorrect generic 400n catalogue for this model
The instrument in your photo certainly seems to be orange on the right-half.. Starting to unravel: linkJust really want to see the correct part numbers. I actually wonder as the "speed warning light" is a purely Japanese market phenomenon, perhaps my first-run jap model (is a '78 jap import) may have arrived stock with these parts. |
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