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Discussion Starter · #1 ·
Hi,
After nearly three years I’m soooo close to getting my little Benelli on the road. It’s a 1972 125 Sport Special with the ‘egg’ motor. After some trials it is together enough to be safely rideable and it is now registered on a ‘K’ plate so good to go.

But ... the electrics.

The headlight switch was (is) in a poor state. It has at some time been broken and glued back together. I thought I had a replacement but it’s not the same so I’ve mended the old switch which now seems to work. The bike starts (eagerly) so that side of things is fine.

My issue is with the lights, although I have over 6v at the switch and even at the bulb holder the lights don’t light. With the engine running there is a glimmer which increases with engine speed on both head and side lights.

I have a new (Motobatt) battery on order but what els3 should I be looking at?

The bike is wired as per the diagram below:
Schematic Font Handwriting Rectangle Material property


Many thanks.
 

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Hi Stu,
The first thing I would check is the earth wire(s) from your lights. Then all the wiring to your lights, including the switches. If they are all good then the next suspect is your dynamo. The surest way to test this is to measure the voltage in your battery before you start it. Then start it up and run the engine for at least 10-15 minutes. Then check the voltage again. If the voltage has dropped then either your dynamo is faulty or your regulator.

Good luck,
Richard.
 

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On my 125 Benelli it has a similar switch to yours, the brake light and parking lights run off the battery and the main and dip beam run directly from the stator. Hope this helps
 

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Running a separate earth wire back to the engine case from headlamp housing may be a good idea.
I have a 73 250 SS and I think wiring is likely the same. I also recall headlamp runs off AC and battery is not even in the circuit for running it.
Lights are pretty darn poor even when working correctly.
 
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Discussion Starter · #5 ·
Thanks both.
It’s helpful to know about the side and headlights being different, thanks.
New battery arrived today so I’ll connect that up and see what happens
 

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Discussion Starter · #6 ·
Hi
Just to round things off.
I also got in touch with the Wards-Riverside forum and was directed to earthing the battery.
A few minutes with the soldering iron and I’d added an earth wire attached under one of the side panel bolts and everything is now as it should be.
Thanks for all the help.
Regards
 
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