MRC Forum- brought to you by www.morini-riders-club.com

Hello,

I’ve been enjoying my ’81 Kanguro as a daily rider, but recently it has started blowing headlight bulbs regularly.

I find the 6v / 12v system a little confusing so I’ve just re-drawn the wiring diagram from the handbook as an exercise in getting my head around its workings - attached here since I figure anyone with a X1 Kangaroo might also find it useful! (the scans on the internet are terrible!).

However, since there is still a little ambiguity in the diagram (eg no switch circuits etc) can someone help me with a few basic principles here?

From what I can tell by looking at the diagram, the MAROON wire from the reg/rec outputs 6v DC (fed to lights and indicators) and one of the GREY wires from the reg/rec outputs 12v DC for the headlights only. Is this correct? And if so, then the reg/rec is probably the culprit for blowing headlights. And if so, then it’s a very unusual and specific reg/rec!

I haven’t started measuring voltages on the bike itself yet because first, I wanted to get a better understanding of what I’m looking for. Any insights would be greatly appreciated!

Greg

PS - restrictions on file size mean that the attached diagram is quite low res. PM me if you want a super high res version!

Hi Greg, your regulator/rectifier should give AC 12 v from the grey wire. The reg/rec unit should also limit the voltage being supplied to the headlamp as well, as I only recently learned! I had thought it was merely a connection point for the AC supplied direct from the flywheel. What I learned from Benjy Straw is that there are components in there to restrict the voltage and that they are now starting to fail regularly as they are all getting on a bit! Some of them fail open circuit so no voltage regulation while some others develop a higher resistance and the headlamp beam gets progressively dimmer!
As yours may be offering less resistance it at least gives you the chance of a cheap fix (maybe short term only, who knows?) by adding a resistor in the grey wire fix. I'm sure Benjy posted an easily available gizmo that was fitted to various mopeds for the same purpose. If I can find it I'll repost it.

How nice to see a decently executed wiring diagram. What did you use to draw it?

Steve Brown wrote: 16 Mar 2025 16:15 Hi Greg, your regulator/rectifier should give AC 12 v from the grey wire. The reg/rec unit should also limit the voltage being supplied to the headlamp as well, as I only recently learned! I had thought it was merely a connection point for the AC supplied direct from the flywheel. What I learned from Benjy Straw is that there are components in there to restrict the voltage and that they are now starting to fail regularly as they are all getting on a bit! Some of them fail open circuit so no voltage regulation while some others develop a higher resistance and the headlamp beam gets progressively dimmer!
As yours may be offering less resistance it at least gives you the chance of a cheap fix (maybe short term only, who knows?) by adding a resistor in the grey wire fix. I'm sure Benjy posted an easily available gizmo that was fitted to various mopeds for the same purpose. If I can find it I'll repost it.

Hi Steve,

Thanks so much for the helpful info.

Yes, I put a meter on the bike today and it all fits with your hypothesis. The reg/rec is putting out about 12V AC but peaks out to 14V AC under revs (to about 5000rpm). So this is likely the cause of headlight bulbs blowing.

Since I'm using this bike all the time, I might put a 12 AC resistor in-line at the output of the reg/rec as you suggest as a quick fix. Then I'll try and find a replacement reg/rec - if I can find one of course. Will try the usual suspects (M'dina and a few old contacts I have in Italy).I haven't dealt with Ben Straw in about 100 years - do you have his current contact details?

Cheers!

Greg

3potjohn wrote: 16 Mar 2025 17:05 How nice to see a decently executed wiring diagram. What did you use to draw it?

Thanks!

I just use Illustrator for all my drawings - both creative and technical. My career started out in design, so it's all I know. I recently used it to design a wiring diagram from scratch (for a custom Ducati-based bike I'm building). Although it's not really designed for that sort of thing, it's super flexible and so you can pretty much do anything with it. Let me know if you want a higher res version (PM me for email details).

Hi Greg, Benjy is running a workshop in Kent these days and his contact details are in ATG each month. Straw Auto Moto Electrico with email address straw.benjy@btinternet.com