Hi all, I’m new to Guzzi ownership as well as club membership, I would appreciate some advice please. Forgive the long post, and please note I am not a mechanic / electrician!
I rode the bike home after purchase, some 20 miles, and didn’t have any problems apart from one of the indicators not working. The indicators fitted were aftermarket LED’s, cheap and a bit worse for wear so I have replaced them with new LED units. Did the rears first, all 4 working (with the original fronts). It then wouldn’t start, however the starter is cranking over fine, and no instrument lights. One of the 4 fuses had gone, replaced that and now have instrument lights.
The rear light is also an aftermarket LED item in case that’s relevant.
I changed the front indicators at the weekend, none of them worked. Just changed the relay and now have indicators except LH front - the wiring goes to a bolt on the frame (?!). When I turn the lights on the rear indicators come on, but don’t flash. The bike has had electronic ignition fitted at some point so the original wiring diagram is pretty useless. It also has 2 batteries for some reason (1 for the ignition?).
So, I have a bike that doesn’t start and with dodgy electrics, any suggestions welcome. Also recommendations for a good auto electrician in Yorkshire please (I live near Scarborough) as I think I’m going to need one! Thanks in advance.
Lack of a good earth is often a reason for indicators not working. You should be able to see if you have voltage going to each indicator with a voltmeter set to DC volts.
As for lack of starting, check to see if you have a spark by taking a plug out, put it in the cap, lay it on the rocker box so the metal is touhing and crank it over, you should see a spark.
As for why it has 2 batteries, that is a complete mystery!
Also - all the led lights i have encountered will only work if the wires are connected to the correct polarity (unlike incandescent which will glow whichever way the electrons flow).
Plus if the original flasher unit is still there the led indicators offer too little resistance and will flash fast unless there is a ballast resistor either inside them or in line with the power line.
are they 6v batteries wired in series?
AS far as I know the v50ii was fitted with a bosch electronic ignition system - looks the same as the one on the Morini 350 & 500.
Anyway it was not unreliable (when newish) except
- if the battery voltage drops too low during starting the ignition will not trigger Anything below 10v is not gonna work. Firstly check the earth and live battery terminals as resistance there can lose a volt or two!
- it had no advance curve so the engine had a massive bottom end flat spot.
V50iii and v65 changed to points and an auto advance (!) but you cannot go there without the newer camshaft 
Thanks for your reply, I haven’t tried the spark test yet - will do that at the weekend.
Thanks for your reply. The indicators flash with the lights off, apart from the LH front (I need to check the wiring) however when I turn the lights on the rear indicators are just on and no flash from either of the front.
Thanks for your reply. No, 2 12v - not something I’ve seen before!
Also meant to add that the ignition system is not original, can’t remember the make right now but it makes the wiring diagram largely redundant!
If it is a Silent Hektik system there is information here http://www.motoguzzisales.co.uk/Silent%20Hektik.htm
It is, thanks for the information. I’ll have a read through at the weekend and see if it sheds any light on the issue.
Thanks to all that replied to my earlier post. The bike now runs fine due to new spark plugs and making sure the ignition circuit connections were sound. I am still trying to get the rear light and indicators to work properly, any advice welcome. I’m pretty sure the connections up to the wiring at the rear light / indicators are correct. I initially mimicked the existing connections to the old indicators as best I could, and the indicators worked unless the lights were turned on in which case the rear indicators just came on without flashing. I have replaced the relay.
I’ve outlined the wiring below with questions:
Power to the indicators - red and black wires
(Aftermarket) indicators - red, black and white. Are the white wires earth? If so do they need earthing individually or can they be combined in one connection?
Power to the (aftermarket) rear light - red, black and yellow. Is the yellow earth?
There is also an earth wire to a bolt in the light housing, should the rear light be connected to this?
Thanks in advance!
If the old indicators worked without the lights on but stop flashing with the lights on, then it sounds like the battery needs charging, possibly replacing.
The earth wire to the light housing should be fine so long as everything is metal up to the bulb.
Sorry, I can’t help with the wiring to the indicators, you are best to experiment with a wire off the battery to see if you can get them to work then try and connect them into the bikes wiring.
As previously mentioned, some LED lights will only work if they are wired up in one direction and don’t work the other way. If they are plastic bodies, they will jus have 2 wires in and out. One of them will need to be earthed to complete a circuit. No idea why yours have 3 wires?
Thanks for the reply. The indicator housings are metal, so the white wires could be earth. The ones originally fitted were plastic. The bike has 2 12v batteries and both are charged (and hold a decent charge, I still need to investigate why there are 2!
The colours of the wires to the rear light and indicators are not standard but you said that these were aftermarket. Are they LED?
Original wire colours were
Yellow - tail light
Blue/red - brake light
Pink - RH indicator
Green/black - LH indicator
Black - earth
There is a 4-way connector block near the rear mudguard with the four coloured wires (not earth) from the loom, the loom side of the connector block should have the correct colours as I have noted above.
Test your lights and indicators with a battery to see which wires make them work then connect to the relevant wire in the 4-way connector block.
Best of luck! PS I produce coloured wiring diagrams, and I have one for the V50II but not with the aftermarket lights you have described.
Thank you. Yes, the indicators are LED. I haven’t yet looked at the connector, that’s next on the list!
If there is no good earth for the rear lights and indicators, the indicators can earth through the lights circuit when it is not powered up.
As soon as you join that circuit to power the indicator electrons have no route to earth, so the indicators wont flash.
This problem will also involve the brake circuit.
Thanks for your reply. I need enough time to work through the wiring…..could do with a rainy weekend!
Afternoon, I’ve had some time today to have a look at the wiring and any further advice would be much appreciated.
The bike has the 4 coloured wires as you have described but no earth (the connector block in the photo is mine, the wires were just twisted together). Wires to the rear consist of 2 sets of red and black wires and nothing else - are these original? If so how do the 4 coloured wires connect? Wires coming from the rear light are black, red and yellow; each indicator has black, red and white and there is an earth to a bolt inside the light mounting plate. I’ve tried various combinations of connections but have only managed to get the brake light to work.
As noted above
Yellow - tail light
Blue/red - brake light
Pink - RH indicator
Green/black - LH indicator
Other wires are non-standard. The black and red wires look like old domestic cables, I have no idea what they do as I do not know where they are connected.
The indicators only need two wires each, feed and earth.
I suggest that you run new wires from your Lego brick connector as noted above. I would also suggest that you use the black wires as earths and connect all earths to somewhere further forward to the frame near the battery earth.
Someone has replaced the existing wiring to the rear lights and indicators and it all appears to be non standard.
Best wishes Chris