Mystery electronic device on my VFR750

[stinkwheel]

No idea what it is and it's not on the wiring diagram.

So it's a 1992 Honda VFR750 FN.

I found a bug lump of self amalgamating tape wrapped in PVC tape hanging off the loom at the front of the VFR. Pretty much just flapping about on the end of its wires.

I ALWAYS investigate big lumps of PVC tape, I don't trust them, especially with the horriffic degree of bodgery that has already been carried out on this bike.

SO. It's got a small PCB inside it. It's attached to the loom with a very original looking connector block and has a green earth wire, a black on brown live wire and an orange wire with a blue tracer. The orange wire comes off the loom at a bullet connector then attaches into the connector block and is about five times as long as the other two wires (possibly as if it is meant to go somewhere else first?).

I can't find an orange and blue wire anywhere on the wiring diagram, nor any mention of this PCB. It looks like it's designed to screw down to something, but it isn't.

I want to know what it is, because if it's something like a restrictor, I want it off and if it's a rev limiter modifier or ignition advancer, I need to know because I habitually bounce them of the limiter.
https://i48.photobucket.com/albums/f216/stinkwheel/CIMG0824_zps3f0e4e3f.jpg
https://i48.photobucket.com/albums/f216/stinkwheel/CIMG0825_zpsfbce85e5.jpg
https://i48.photobucket.com/albums/f216/stinkwheel/CIMG0826_zpsd1d6f04f.jpg
https://i48.photobucket.com/albums/f216/stinkwheel/CIMG0827_zpsde92efba.jpg

Any ideas?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Fizzer Thou]

That looks like an opto-coupler,though it would need a flag of some sort to interupt the beam bewteen the two black pieces on the blue mounting in order for it to be switched.
TR1 components are transistors that cold be used to bias the triggers.

Honda have used light blue and orange for left and right indicator switching in the past.

In the last picture there is a wire soldered to a post that says 'IGN' on the PCB which may also be a clue.
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Just talk bikes.What else is there?

Always have a 'Plan B'

[Frost]

Looks like one of the 180kph speed limit removal boxes you fit to a VFR 400. Same size, plug type, wire could, colour and location. It might also bee a speedo healer?

Unplug it and go for a ride

[Knightsy]

It's the MI5 tracker. Expect a visit soon
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09' Versys 650 | 07' FJR1300A

[Islander]

That's certainly an opto-coupler and as Fizzer pointed out, they usually have something that interrupts the beam between the transmitter side and receiver side. However, it could be being used as an opto-isolator to physically separate input from output. Unusual, but not impossible.

What markings are on the PCB where the wires join? There's the IGN (ignition) one and the one next to it looks like it might be GND (ground) what are the other one(s)? That might provide a clue.

[The Artist]

[The Artist]

[Islander]

[stinkwheel]

The brown on black wire is a switched live and reads "IGN"

The green wire is an earth and reads "GND"

The blue on orange has a low 0.15VDC voltage which increases with revs up to about 0.6VDC.

The speedo is (mechanical) cable operated.

So putting something between those black bits would alter whatever it does? Like on an optical ignition? Weird. It was all wrapped up in black tape and I'ver been over the main parts of the ignition system when I removed the generator cover and subframe to repaint them. They seemed totally unmolested.

EDIT: What would one of these things be doing on a 20 year old Honda?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Islander]

Basically, yes. One half of the device has an LED, the other a photodiode or phototransistor. Passing something through the slot interrupts the light beam (usually invisible infra red) and causes the output to change.

As to what it's doing on a 20 year old bike? I have no idea. They've been around for longer than that though.

Is there a marking where the other wire joins the PCB?

[stinkwheel]

[Suntan Sid]

Has the CDI unit been replaced?
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"Everybody needs money, that's why they call it money!"

[stinkwheel]

[Islander]

Yep, 'Fraid so.

[map]

This may be teaching you to suck eggs but have you asked on the VFR or Honda owner sites?

I am intrigued now and want you to find what it is
____________________
...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?

[stinkwheel]

[The Artist]

I reckon this is some sort of custom modification. Possibly some sort of restrictor or part of the spark generation system.

More likely it is some custom control system modification someone made and just left attached. We can probably work out what it was for if you trace the wires or find the correct original wiring diagram for your bike.

Where did you get it from?

[Martay]

Its the speed limiter iirc. Fitted in the clocks, theres a little panel which blocks the signal passing between the 2 black 'towers' at the relivant speed. This triggers the limiter.
By removing it from the clocks, it effectivly doesnt know its doing over the limit.
Saw this done also on Billings VFR400 thingy.
EDIT: When blocking the signal, it cuts the spark to 2 of the cylinders.
____________________
Eat well, poo hard
Drives: Cavalier 2.0 16v
Rides: Slightly ratted Honda City Express

[Islander]

[Spudly]

That's fascinating, I hope you find out what it does.
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The Old Apprentice

[stinkwheel]

Errr.

I've removed the front brakes in anticipation of my totally kick-arse pretech brake callipers being delivered.

As such, checking for a maximum speed restriction may be a trifle hazardous at this stage...

I'm going to have to peel the loom back and follow the wire. It's too anoying not knowing what it's for.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[_Iain_]

Could you not put it on paddock stand or whatever & run it up to that wheel speed? Then whack something across the blocks & see if it misfires?
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Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[stinkwheel]

[stinkwheel]

I'll pull the speedo out tonight to have a look if there's somewhere for it to go but I can find no reference anywhere to the 750 models having a top speed restrictor.

I've got the official workshop manual too and it's not mentioned in there.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[sickpup]

It's a speed restrictor out of the speedo. Chances are the bike is a Japanese import that has had its clocks replaced which is why you don't have a 55mph red light and also why there is no space for it in the speedo case.

Check a Japanese wiring diagram and you will probably find it.