Help! Potential Electrical Disaster!

Hi ,
I have recently acquired an 82 V50III in working order (it started) . Having been in storage the battery was flat so I took it out and recharged - simple job - expecting it yto be hjust as simple going back in however … connecting positive terminal wires first (6 in total) - slight spark at terminal - negative wires next (2 in total) - bigger spark, then headlight came on & neutral light!! - as I looked to check all switches/ignition were off - horrible smell & smoke from one wire on positive terminal !! - removed negative connection immediately - all stopped but … green wire coating on positive fried…

According to the v50 workshop manual wiring diagram I have downloaded there are only 2 wires to the positive terminal (1 red & 1 black) & 1 wire to negative ( 1 black to earth)
On my bike ;
6 wires to the positive (4 red (2 together & 2 separate) , I green & 1 grey)
2 wires to the negative (both black)

Fuses still seem intact

Not going to touch again until maybe some advice from here please. How is something that should be simple causing such an issue? Can someone please out me right!?
Many thanks

Hi, it would appear that the wiring has been modified in the past! The wiring diagram you have was it by Carl Allison from Greg Binder’s this old tractor site? I have also produced a colour wiring diagram for this model and can send you a pdf via email. If you would like one please send me your email address via PM (Private messages) on here, rater than posting your email on the public forum. I know that there are a few idiosyncrasies on Carl’s diagrams, they are mostly very good but when I was drawing my ones I noticed some wire colours did not agree with the Italian originals, not in all cases but in some.

Best wishes.

I hope the wiring diagram and advice helps you. Ask away if you have any other questions

Regards Chris

Thanks to Chris I have been able to make some progress but not fixed yet - problem is green wire but…the wiring is definitely non-standard (bike does have a double headlamp within a fairing…) .Having tried to trace wires and test I now know that all handlebar functions all work when connected together (excluding green)…so the question is… what does the green wire do!! Any ideas on what next welcome …note: the starter clicks but on one try …starter does not turn…so low current connection works? Green wire is not a heavy wire so not high current so it’s not that behind any starter issue?

Hi Roy, as I said before the green wire is non-standard so could go anywhere, you will have to trace it. Try following the loom and see where it pops out.

Best of luck Chris

Hi All (especially Chris!),
I was able to find an electrical specialist snot scared by Italian electrics & their reputation who came to work on the problem last Friday.
Turns out that the Previous Owner had indeed modified the wiring & not only to install the double headlamp . The standard separate rectifier/regulator set up has been replaced by a modern dual function unit . The Green (burnt ) wire connected to the new (rectifier) unit and direct to the generator replacing the y-y connection on the original V50 wiring diagram connection - this wire had burnt along the whole length when I tried to re-install the battery after charging and was therefore completely replaced . Luckily it did not seem to have affected any other wire or function along its length .

The DF connection from the generator to the (regulator) new unit was a brown wire .

Replacing the green wire and swapping a mis-placed black wire from -ve to +ve ! restored all functions and the motor started & ran fine - no sparks , burning or any sign of issues however … having overcome this hurdle the wiring is sufficiently questionable & untidy to warrant a complete re-wire/new loom sooner rather than later :slight_smile: Any advice on who might be experienced and able to do this and a likely cost would be welcome !
Thanks Roy

Hi Roy
Inheriting other peoples wiring is always interesting, I’m sure it made perfect sense to the previous owner.
Not sure where abouts you are in the country, but if you are any where near Nottingham, Towzer is your man for a rewire
Baldrick is in South london and is equally as good

I have heard that Baldrick is seeking new premises, not sure of the details as this is second hand news.

Hi ,
Put a gallon of petrol in the bike - turned taps to ‘on’ and primed ready to start and 20 seconds later the left hand carb was dripping petrol profusely …or actually …it was dripping from the pod air filter!

Let it dry a couple of days and just tried again without priming …same result .
Any brigh ideas or just plain old experience to lead me to the solution ? …presumably the float bowl is filling & the petrol is then finding the easiest way our back to the filter …right hand carb dry as a bone
Thanks in advance

The floats can stick, a quick solution is a tap on the float bowl with the handle of a screwdriver, the better solution is to take them apart and give it a clean out, probably some muck in the float needle.

Thanks Don - decided to go down the strip , clean/replace route
Best Roy

Hi All
Just about to replace the original indicators on the V50 III with some modern LEDs - anyone have any similar experience ? I am thinking to install an LED specific new Flasher Relay to drive them rather than an in-line resistor (whose value would be based on ??? :slight_smile:)
If anyone has a recommendation on the relay that would be welcome!
Thanks Roy

The resistance of the LED indicators will not be the same as filament bulbs hence the need to either add resistance to the circuit or change the flasher unit for a compatible one. The latter sounds easier to me. I fitted a pair of LED bulbs to the rear light on a Spada III I once had, before when I touched the brakes the headlamp dimmed, after fitting the bulbs it was excellent, no dimming of the headlight and the rear light and brake light were much brighter. The bulbs were like christmas trees with LEDs all round, they also had built in additional resistance so they were plug and play. They were not cheep though, about £25 each, but we are going back nearly 10 years …

Thanks Chris - wondered if you would reply!:slight_smile:
It’s also possible apparently now to buy an indicator relay that does away with the need for in-line or built-in resistors…
Best Roy

as you say – in a flasher unit!!

Old school :smiley: